| MISSION_DESCRIPTION |
Mission Overview
================
Venus Express is ESA's first mission to Venus. It reuses the design
of the Mars Express spacecraft. Many of the instruments are simply
upgraded versions of those developed for ESA's Mars Express and
Rosetta missions. The scientific objectives of the mission is to
study the atmosphere, the plasma environment, and the surface of
Venus in great detail.
Venus Express was launched by a Soyuz-Fregat launcher from the
Baikonour Cosmodrome on 9 November 2005. After separation, Venus
Express, of mass 1244 kg,was placed into an interplanetary transfer
orbit during approximately 150 days. After a 153 day cruise to Venus
the spacecraft entered Venusian orbit on 11 april 2006. The first
capture orbit was an eccentric polar and lasted 9 days. Several
manoeuvres over the period 15 April-6 May 2006 lowered the spacecraft
into its operational orbit: a 24-hour elliptical, quasi-polar orbit.
The pericentre altitude is 250 kms and the apocentre altitude is
66000 kms.
Pericentre altitude 250 km
Apocentre altitude 66000 km
Period 24 h
Inclination ~90 deg
Pericentre latitude 80 deg
The mission has been described in many papers [ESA2005;
HUNTER2004]. Details about the mission launch sequence and timeline
can be obtained from the Mission Calendar [DAUVIN2005] and from
the Consolidated Report on Mission Analysis (CREMA)
[SANCHEZ&RODRIGU2005].
Mission Phases
==============
The mission timeline defines the different spacecraft and payload
operations required per phase to prepare the spacecraft for Venus
operational orbit acquisition, science data acquisition and
transmission.
The pre-routine mission phase, which are:
- the pre-launch phase
- the launch and early orbit phase
- the near earth commissioning phase
- the interplanetary cruise phase
- the venus orbit insertion phase
- the venus orbit commissioning phase,
the nominal mission phase and the extended mission phases phase are
detailed below.
PRELAUNCH
---------
Pre-launch operations started approximately 6 months before the
launch and covered the period from delivery of the spacecraft to the
launch site until L-8 hrs in the launch countdown sequence. During
this period the Venus Express Mission Operations Centre (VMOC) at
ESOC performed its final simulation programme including the validation
of the Flight Operations Plan (FOP) and the final mission control
system.
mission phase start time : ~ June 2005
mission phase stop time : 2005-11-09
LAUNCH AND EARLY ORBIT PHASE (LEOP)
-----------------------------------
The Venus Express spacecraft was launched on a Soyouz-Fregat rocket
from the Baikonur Cosmodrome at 3:33:34 UT on 9 November 2005.
The three-stage Soyuz launcher lifted the Fregat autonomous upper
stage (fourth stage) with Venus Express mounted on it into a
sub-orbital trajectory.
After separation from the Soyuz third stage, a Fregat main engine
burn (at an altitude of about 200 kilometres) for around 20 seconds
placed the Fregat-Venus Express composite into an almost circular
parking orbit. After a coast phase of about 70 minutes in the low
Earth orbit, a second Fregat engine burn, lasting 16 minutes, moved
the combined craft from the parking orbit onto an escape trajectory,
after which the Fregat stage and Venus Express separated.
Duration : 3 days
mission phase start time : 2005-11-09
mission phase stop time : 2005-11-11
After separation, Venus Express spent approximately 150 days in an
interplanetary transfer orbit. During this phase, trajectory
corrections were performed using the spacecraft's own thrusters.
NEAR EARTH COMMISSIONING PHASE (NECP)
-------------------------------------
It included the following activities for the spacecraft:
- spacecraft commissioning.
- deployment of the MAG Boom.
- Payloads commissioning.
Duration : 3 weeks
mission phase start time : 2005-11-12
mission phase stop time : 2005-12-16
INTERPLANETARY CRUISE PHASE
---------------------------
The Interplanetary Cruise Phase finished about one month before Venus
capture. During this 3 months phase, the spacecraft was on the
Sun-centred ballistic orbit to Venus. Most of this phase was not
dedicated to any specific activity, except the cruise orbit
determination and correction.
Duration : 107 days
mission phase start time : 2005-12-17
mission phase stop time : 2006-04-04
VENUS ORBIT INSERTION PHASE (VOI)
---------------------------
The Venus Orbit Insertion (VOI) phase was the period of transition
between the Interplanetary Cruise phase and the final operational
orbit around Venus. It started before the Venus capture manoeuvre and
ended when the satellite reached the operational orbit. The duration
of this phase was about 2 weeks.
A final course adjustment was performed on 29 March to fine tune the
arrival hyperbola for Venus Orbit Insertion. The VOI manoeuvre took
place on 11 April 2006. To enable capture of the spacecraft, it was
first slewed such that the main engine was aligned to the direction
of travel.
The main engine burn lasted around 50 minutes and decelerated the
spacecraft by approximately 1251 ms-1 (~ 4500 kmh-1).
The spacecraft initially entered a highly elliptical polar orbit with
a pericentre of 400 km, an apocentre of 350 000 km and a period of 9
days.
To achieve the final operational orbit a series of correction
manoeuvres were necessary:
Date Activity Velocity Change (m/s)
15 April 2006 Pericentre Control Manoeuvre #1 5.8
20 April 2006 Apocentre Lowering Manoeuvre #1 199.9
23 April 2006 Apocentre Lowering Manoeuvre #2 105.3
26 April 2006 Apocentre Lowering Manoeuvre #3 9.2
29 April 2006 Apocentre Lowering Manoeuvre #4 8.0
2 May 2006 Apocentre Trim 2.0
6 May 2006 Pericentre Control Manoeuvre #2 3.1
Duration : 16 days
mission phase start time : 2006-04-05
venus capture manoeuvre : 2006-04-11
mission phase stop time : 2006-04-21
VENUS ORBIT COMMISSIONING PHASE
---------------------------------
The Venus Payload Commissioning phase started when the spacecraft
reached the operational orbit and ended when it was declared ready for
science data acquisition and transmission to the Earth.
It was dedicated to spacecraft commissioning activities, payloads
commissioning and demonstration activities prior to operational
science operations.
The duration of the Payload Commissioning phase around Venus was about
1 month.
The operations to be performed during the phase were the following:
- S/C in-orbit commissioning,
- Payloads in-orbit commissioning,
- Isolation of the Propulsion system.
Duration : 42 days
mission phase start time : 2006-04-22
mission phase stop time : 2006-06-03
ROUTINE OPERATIONS PHASE
------------------------
The selected operational orbit was inertially fixed, so that coverage
of all planetocentric longitudes was accomplished in one Venus
sidereal day (243 Earth days). The nominal mission orbital lifetime
was two Venus sidereal days (486 Earth days). It consisted in science
data acquisition from the payloads, data storage in the SSMM and data
transmission to the Earth.
There were two different phases of operations for Venus Express once
it was in operational orbit: the Earth Pointing phase and the
Observation phase.
The Earth pointing phase was dedicated to communication with Earth and
battery charging. It was used whenever the spacecraft was not in the
observation phase. In the Earth pointing phase, one of the two High
Gain Antennas was oriented towards Earth. The antenna was selected
according to the season, so that the spacecraft's cold face remained
always protected from illumination by the Sun.
The rotation angle around the Earth direction was optimised in order
to avoid any entrance of Sun light on the side walls radiators.
High rate communication was performed 8 hours per day in X-band, in
order to transmit to Earth all science data stored in the Solid
State Mass Memory.
An average of 2 Gbits of science data was downlinked every day to the
new ESA ground station of Cebreros, Spain.
The observation phase consisted of several different modes of
observation, depending on the payload configuration and spacecraft
orientation: Nadir pointing, Limb observation, Star occultation,
Radio science.
During observation, the Sun could illuminate under transient
conditions any spacecraft face, except for the cold face. The duration
of observation was therefore limited by thermal constraints and by
battery discharge. The maximum duration of an observation period
depended on the Sun direction with respect to the orbit plane, which
varied along the mission.
Observations and spacecraft activities were planned based on the
following principles:
1. Complete and uniform the coverage of the science themes
2. Balance between distant and close-up view of Venus
3. Balance between observations of the Northern and Southern
hemisphere
4. Synergy between experiments in covering science objectives
5. Use of two cases in each orbit: one in apocentre, one in
pericentre
6. Even distribution of pericentric cases with priority given to the
solar and Earth radio occultation experiments in specific seasons
7. Apocentric cases (2,3) were grouped in campaigns of 10 orbits
that was required by the atmospheric dynamics mission objectives
8. Maximum compliance with the current flight rules.
Individual Objectives per Instrument
------------------------------------
ASPERA
On during the entire mission and permanently collecting data.
Survey observations in the beginning of the mission and more specific
and detailed observations on selected part of the orbit later in the
mission. Data was collected at different rates depending on the
selected mode.
MAG
On during the entire mission and permanently collecting data. Data was
collected at different rates depending on the selected mode.
SPICAV
The main goal of SPICAV was to sound the Venus atmosphere in solar and
stellar occultation geometry with sufficient latitude and local time
coverage. SPICAV did also nadir and corona observations (90 deg slew
from nadir pointing and back to nadir).
VeRa
4 types of observations
1. Earth occultation with as good as possible latitude and local time
coverage of Venus.
2. Bi-static sounding of surface targets. The radio signal was sent to
selected targets on the Venus surface. Reflected and scattered signal
was received by ground station. As the signal was weak, the experiment
depended on the Earth Venus distance, geometry and surface target
properties.
3. Solar Corona observations in vincinity of conjunctions.
4. Gravity anomaly. It consisted in the precise tracking of the s/c
while it passes over global geological formations on Venus solid body.
It has been carried out only twice during the nominal mission . The
Gravity Anomaly observations have been abandoned since the end of the
nominal mission as the added scientific value with respect to previous
observations was very small.
Duration : 486 days
mission phase start time : 2006-06-04
mission phase stop time : 2007-10-02
EXTENDED OPERATIONS PHASE
-------------------------
The nominal mission ended on October 2, 2007 when started the first
extended mission. The first extended mission phase was approved until
May 2009, end of MTP 040, May 30th, orbit 1135. It was followed by the
second mission extension from MTP 041 that started in May, 31 2009
(orbit 1136). The second extension was followed by the third extension
that started with MTP 057, August 22nd 2010, orbit 1584. The third
extension ended with MTP 085 in December 2012.
Summary of extended mission phase
---------------------------------
NOMINAL MISSION
MTP 002
Day 4 June 2006
Orbit 44
EXTENSION 1
MTP 019
Day 3 October 2007
Orbit 530
EXTENSION 2
MTP 041
Day 31 May 2009
Orbit 1136
EXTENSION 3
MTP 057
Day 22 August 2010
Orbit 1584
EXTENSION 1, 2, 3: General Observation strategy
-----------------------------------------------
The first extended mission had the following objectives:
- Improve and complete spatial and temporal observational coverage
- Study in detail the phenomena discovered in the nominal mission
- Take advantage of the new operation modes (case #2 pendulum,
spot pointing, ...)
- Perform pericentre lowering down to the altitude that still
allows usual operations without entering aerobraking mode
(around 170-270 km)
- Perform necessary studies and tests preparing the spacecraft for
future aerobraking campaign
These goals determined the following planning outline for the
extended mission:
- October 3, 2007 - May 31, 2008 (MTP 19-27): like nominal mission
- June 2008 - TBD operations with low pericentre.
- TBD: Aerobraking campaign.
Pericentre lowering campaign:
The pericentre altitude was maintained between 250 km and 350 km
during the first 8 months of the extended mission. After May 31,
2008 the pericentre was lowered to the corridor 170-220 km. This
pericentre lowering aimed at observing plasma at this altitude
range. The apocentre and the pericentre latitude hasn't changed
(66000 km, about 78 deg).
Science Subphase
----------------
For the purpose of structuring further the payload operations
planning, the mission phases were further divided into science
subphases.
Phase number Date Orbit
CRUISE 2005-11-09 -1
VOI 2006-04-11 0
PHASE 0 2006-05-14 23
PHASE 1 2006-06-04 44
PHASE 2 2006-07-11 82
PHASE 3 2006-09-14 146
PHASE 4 2006-11-16 209
PHASE 5 2007-02-01 286
PHASE 6 2007-03-16 330
PHASE 7 2007-04-25 370
PHASE 8 2007-06-30 436
PHASE 9 2007-08-21 488
PHASE 10 2007-10-04 531
PHASE 11 2007-10-27 554
PHASE 12 2008-01-04 623
PHASE 13 2008-04-01 711
PHASE 14 2008-06-05 776
PHASE 15 2008-08-01 833
PHASE 16 2008-09-23 886
PHASE 17 2008-12-31 985
PHASE 18 2009-03-02 1046
PHASE 19 2009-05-05 1110
PHASE 20 2009-06-24 1160
PHASE 21 2009-09-20 1248
PHASE 22 2009-10-18 1276
PHASE 23 2009-12-17 1336
PHASE 24 2010-02-02 1383
PHASE 25 2010-04-07 1447
PHASE 26 2010-05-30 1500
PHASE 27 2010-07-12 1543
PHASE 28 2010-07-30 1561
PHASE 29 2010-09-14 1607
PHASE 30 2010-11-19 1672
PHASE 31 2011-01-17 1732
PHASE 32 2011-03-23 1797
PHASE 33 2011-04-26 1831
PHASE 34 2011-06-14 1880
PHASE 35 2011-08-27 1954
PHASE 36 2011-10-25 2013
PHASE 37 2011-12-05 2054
PHASE 38 2012-01-08 2088
PHASE 39 2012-02-05 2116
PHASE 40 2012-03-04 2144
PHASE 41 2012-04-01 2172
PHASE 42 2012-04-29 2200
PHASE 43 2012-05-27 2228
PHASE 44 2012-06-24 2256
PHASE 45 2012-07-22 2284
PHASE 46 2012-08-19 2312
PHASE 47 2012-09-16 2340
PHASE 48 2012-10-14 2368
PHASE 49 2012-11-11 2396
PHASE 50 2012-12-09 2424
VOI and Phase 0
-------
This initial phase was devoted to the spacecraft and payload checkout
and in orbit commissioning. The phase consisted of:
- experiments commissioning (until 14 May 2006, orb 23).
- Science case commissioning (16-27 May 2006, Orb 23-36).
- Extended case commissioning (May 28-June 3, Orb 37-43). The ECC
also occupied the first half of phase 1.
The phase contained the first eclipse season that ends at orbit 40.
VOI
---
Dates : April 11 - May 13 2006
Orbits : 1 - 23
Phase 0
-------
Dates : May 14 - June 03, 2006
Orbits : 23 - 43
Phase duration : 20 days
MTP : 1
Phase 1
-------
Phase 1 was favorable for observations of the evening terminator
vicinity. In particular, the following observation were performed:
- Cloud observations;
- lightning on the night side;
- stellar occultation on the dark limb (north/south asymmetry of the
aerosol vertical structure);
- Solar occultation (horizontal structure of hazes above the main
cloud deck);
- Thermal mapping of Ishtar Terra and Maxwell Montes;
- Limb observations (vertical structure of haze layers);
- Observations of nightglows (O2, NO ...), their latitude and
vertical variability;
- Bistatic sounding of the Maxwell Montes (BSR#1)
- Comet Mrkos by SPICAV and VMC on June 5, 2006.
SPICAV observed nadir and stellar occultations.
VeRa performed bi-static sounding (BSR#1) of Maxwell Montes.
VIRTIS observed the evening sector of the planet, night side mosaics,
thermal mapping of Maxwell Montes and limbs.
VMC observed the evening sector of Venus, limbs and perform thermal
mapping of Maxwell Montes.
Dates : June 4 - July 10, 2006
Orbits : 44-81
Phase duration : 37 days
MTP : 2-3
Phase 2
-------
Phase 2 started at the beginning of the first Earth occultation season
in orbit 81 and ended at the end of the 2nd eclipse season in orbit
145. It provided favorable conditions for nadir observations of the
night side.
The following observations had the priority:
- Solar occultations;
- Earth radio-occultations;
- Night side dynamics with high spatial resolution
- Twilight limb observations in forward scattering geometry
- Nightglow observations
- Thernal mapping of the surface
The night side surface targets were Beta Regio, Theia Mons, Phoebe
Regio, Ishtar Terra (Lakshmi Planum).
ASPERA took measurement of the night side plasma.
SPICAV observed in nadir mode and the solar occultations.
VeRa observed during the Earth occultation season #1 and participate
in the gravity campaign #1.
VMC observed the night side: atmopsheric dynamic, night side surface
mapping of the targets listed above. They observed also nightglow and
they searched for lighting.
Dates : July 11 - September 13 2006
Orbits : 81 - 145
Phase duration : 64 days
MTP : 3-5
Phase 3
-------
The Venus dark side could be observed in the beginning of Phase 3.
Phase 3 also had conditions for systematic observations of the
morning/evening terminator and for solar corona studies. The phase
contained the first superior solar conjunction (orbit 179-201).
The following observations were performed:
- Cloud at terminator (study of cloud and haze structure);
- Coordinated campaign of atmospheric dynamics observations in
Northern and Southern polar regions;
- Search for lighting on the night side;
- Double stellar occultation on the dark limb (north-south assymetry
of aerosol vertical structure);
Mapping of surface targets (Isthar Terra);
- Limbs (vertical structure of haze layers);
- Nightglows (O2, NO...): latitude and vertical variability;
- Solar Corona studies;
- Gravity anomaly #1
ASPERA observed the morning sector.
SPICAV observed nadir and stellar occultations.
VeRa observed the Solar Corona and do the 1st gravity anomaly
campaign.
VIRTIS observed the north/south polar dynamics, the Ishtar Terra night
side target and the morning sector.
VMC observed the north/south polar dynamics, the Ishtar Terra night
side target, the high-resolution atmospheric dynamics and the
nightglow and searched for lightning.
Dates : September 14, 2006 - November 15, 2006
Orbits : 146 - 208
Phase duration : 62 days
MTP : 5-7
Phase 4
-------
Phase 4 started at the beginning of the eclipse season in orbit 209
and ended at the end of the Earth occultation season in orbit 285.
ASPERA observed in details the nightside plasma.
SPICAV observed solar occultations and in nadir mode.
VeRa observe during Earth occultation season and Solar Corona.
VIRTIS and VMC observed on the dayside but also nightside of Theia
Mons and Lakshmi Planum.
Dates : November 16, 2006 - January 31, 2007.
Orbits : 209 - 285
Phase duration : 76 days
MTP : 7-10
Phase 5
-------
Phase 5 started at the end of the Earth occultation season #2 and
ended at the beginning of the eclipse season #4. It had favorable
conditions for observations of the evening terminator. Focus was also
made on the night side. The following observations were performed:
- Cloud observations at terminator (study of cloud and haze
structure);
- North-South atmospheric dynamics;
- Search for lightning on the night side;
- Double stellar occultation on the dark limb (north-south assymetry
of aerosol vertical structure);
- Mapping of surface targets: Atla Regio, Ozza Mons;
- Limbs (vertical structure of haze layers);
- Nightglows (O2, NO...): latitude and vertical variability;
ASPERA observed in details the evening sector.
SPICAV observed nadir and stellar occultation.
VeRa did not observe anything.
VIRTIS and VMC did mosaic and off pericentre observations. They
participated in the North/South pole dynamics campaign. They also
observed the night side.
Dates : February 1 - March 15, 2007.
Orbits : 286 - 329
Phase duration : 43 days
MTP : 10-12
Phase 6
-------
Phase 6 started at the beginning of the eclipse season #4 in orbit
330. It ended with the same season in orbit 369. The phase provided
good conditions for observations of the night side and atmospheric
sounding in solar occultation geometry. Solar occultations were used
to study composition and structure of the atmosphere above the cloud
top. Campaigns of off-pericentre observations and apocentre VIRTIS
mosaic were used to study composition and dynamics of deep atmosphere
on the night side. Conditions was also favourable for observations of
nightglows to study composition and dynamics of the thermosphere and
search for lightning. Limb observations in forward scattering geometry
(spacecraft in eclipse) provided good opportunity to study vertical
structure of hazes above the main cloud. Thermal mapping of the
surface and search for active volcanism was performed. One bi-static
sounding experiment (BSR #4) was scheduled.
The night side surface targets were Beta Regio, Theia Mons and Phoebe
Regio.
SPICAV observed nadir and Solar occultations.
VeRa did the bi-static sounding experiment #4.
VIRTIS and VMC observed off-pericentre and in mosaic mode. They
observed Themis and Phoebe Regio on the night side.
Dates : March 16 - April 24, 2007.
Orbits : 330 - 369
Phase duration : 39 days
MTP : 12-13
Phase 7
-------
Phase 7 started with the Earth occultation season #3 in orbit 370 and
ended with it in orbit 435. Proximity to the Earth created excellent
conditions for bi-static sounding and radio-occultation experiment
that could reach maximum sounding depth. It was used to study the
atmosphere with high spatial resolution. As earlier in phases 1, 3, 5
the terminator sector of the planet was available for observations in
this phase. Cloud structure and atmospheric dynamics were important
goals.
The night side surface targets were Gula and Sif Mons, Guinevere
Planitia, Ishtar Terra, Atalanta Planitia, Atla Regio and Ozza.
SPICAV observed nadir and stellar occultations.
VeRa was on during the radio occultation season 4 and performed the
bi-static radar experiment #5 (Ozza Mons).
VIRTIS and VMC did off-pericentre and mosaic observations. They
observed Ishtar Terra and Maxwell Montes on the night side.
Dates : April 25 - June 29, 2007.
Orbits : 370 - 435
Phase duration : 65 days
MTP :13-15
Phase 8
-------
Phase 8 started and ended with the eclipse season #5 (orbit 436-487).
Thus significant portion of orbits was devoted to solar occultation
observations. This phase was favourable for investigation of dayside
dynamics. Proximity to the Earth provided good conditions for solar
corona studies and bi-static sounding. Gravity #2 target was Atalanta
Planitia, which was poorly covered by the Magellan observations.
The thermal mapping covers Beta Regio, Phoebe Regio.
SPICAV observed nadir and solar occultation.
VeRa did the gravity #2 experiment and bi-static radar sounding #6
(Beta Regio and Theia Mons).
VIRTIS and VMC did off-pericentre and mosaic observations of the
dayside.
Dates : June 30 - August 20, 2007.
Orbits : 436 - 487
Phase duration : 51 days
MTP : 16-17
Phase 9
-------
Phase 9 contained the Earth occultation season #4. It wass favourable
for observations of the vicinity of evening terminator. By the end of
this season conditions for the off-pericentre night side observations
was fulfilled. Main scientific focus of this phase was to provide
observations of the evening terminator. The following observations
were carried out:
- Cloud observations at terminator (study of cloud and haze
structure);
- Search for lightning on the night side;
- Double stellar occultation on the dark limb (north/south
asymmetry of the aerosol vertical structure);
- Grazing solar occultation (horizontal structure of the hazes above
the main cloud deck);
- Mapping of the surface targets;
- Limb (vertical structure of haze layers);
- Nightglows (O2, NO) and their latitude and vertical variability.
The night side surface targets are Atalanta Planitia, coronae,
Guinevere Planitia and Ishtar Terra.
SPICAV observed nadir and stellar occultation.
VeRa did the bi-static radar sounding #6a.
VIRTIS and VMC observed the morning and evening sectors.
Dates : August 21 - October 3, 2007.
Orbits : 488 - 530
Phase duration : 42 days
MTP : 17-19
Phase 10
--------
Phase 10 had no eclipse or occultation seasons. A routine sequence of
off-pericentre observations followed by Nadir, limb or stellar
occultations were carried out.
The night side surface targets were Atla Regio (Sapas, Maat, Ozza
Mons), Zemina corona.
SPICAV SOIR did not make any observation during this phase
(no occultations).
Dates : October 4 - October 26, 2007.
Orbits : 531 - 553
Phase duration : 22 days
MTP : 19-20
Phase 11
--------
Phase 11 started with the eclipse season #6 in orbit 554.
However, solar occultations was only possible from orbit 576 to
596 because of the temperature conditions due to the sun position.
VIRTIS performed some airglow campaign in nadir and limb geometry.
VMC observed the surface on the night side. The observation
targets were Asteria Regio, Hinemoa, Gunda and Kawelu Planitia, Beta
Regio (Rheja and Theja Mons) and Phoebe Regio.
SPICAV observed stars at large distance, later in the phase.
Two spot pointings were performed in orbit 561 and 571 (study of cloud
scattering phase function).
Gravity measurements were performed over Atalanta Planita in orbits
615, 617, 619, 621.
Meteors occurred in orbit 555.
Despite the solar occultation that began 27th October 2007, SOIR did
not make any observation neither calibration until 25th November 2007,
due to thermal reasons in Quadrature period.
Dates : October 27, 2007- January 3, 2008.
Orbits : 554 - 622
Phase duration : 68 days
MTP : 20-22
Phase 12
--------
Phase 12 started with Earth occultation season # 5 and ended with the
eclipse season # 7. Earth occultation season began in orbit 623 and
ended in orbit 692. Pendulum observations were performed during all
this phase. From orbit 659 to orbit 680, three periods overlapped:
Earth occultations, Eclipse season, solar opposition. The solar
opposition was favorable for apocentre mosaics by VIRTIS.
The surface targets for this phase were Atahensik and Zimina Coronae,
Atla Regio (Ozza Mons) and East from it and Atalanta Planitia.
VIRTIS near-IR did temperature sounding in the same region. Then
cross-correlation on results were made possible. From orbit 612 to 631
there was the VIRTIS apocentre mosaic season.
Solar occultations and pendulum observations were mainly performed at
the end of the phase (from orbit 690).
VeRa had the priority for pericentre observations of the Southern
Hemisphere. However, VeRa measurements were not possible from orbit
645 to 658 for NNO maintenance.
Dates : January 3 - March 31, 2008.
Orbits : 623 - 710
Phase duration : 87 days
MTP : 22-25
Phase 13
--------
There was no specific season during most of phase 13. During this
phase, pericentre observations, stellar occultation observations, limb
observations at pericentre were performed. At the end of the phase 13,
in orbit 769, the mission entered superior conjunction phase and
telecommunication outage period (orbit 769 to 790) during which all
science operations were suspended.
Dates : April 1 - June 4, 2008.
Orbits : 711 - 775
Phase duration : 64 days
MTP : 25-28
Phase 14
--------
Phase 14 started with the eclipse season #8 and Earth occultation
season #6. At the beginning of the phase, the superior solar
conjunction prevented any science observations. The eclipse and Earth
occultation seasons overlapped (orbit 777-821). The Earth occultation
period lasted longer up to orbit 832.
The targets for the surface observations were East flank of Atla
Regio, Ozza Mons, Zevana and Paga Chasma.
During this phase, there was a pericentre lowering campaign in orbits
814, 815, 821, 822, 829 and 830.
VMC performed surface imaging and wind tracking.
SPICAV did solar occultations (ingress and egress solar occultations
in orbits 811-819), night and plane limbs and UV observations of the
exosphere on the day side. Stellar occultations may have been
performed in coordination with VeRa. They observed dayglow when flying
perpendicular to terminator. Possibly sub-solar point tracking may
have been performed by SOIR.
VIRTIS performed night limbs together with SPICAV and surface imaging.
The VeRa Earth occultation experiments began in orbit 817.
Dates : June 5 - July 31, 2008.
Orbits : 776 - 832
Phase duration : 56 days
MTP : 28-30
Phase 15
--------
There was no specific season during phase 15. The pericentre lowering
campaign that began in the previous phase ends at orbit 836 and
occurred in orbits 836 and 837.
SPICAV performed night limbs, plane limbs and stellar occultations.
Later in the phase, SPICAV performed day side limbs.
VMC performed wind tracking on the day side.
VIRTIS did night side and terminator monitoring and limb
observations together with SPICAV at the beginning of the phase.
Later in the phase, day side and terminator monitoring was performed.
Dates : August 1 - September 22, 2008.
Orbits : 833 - 885
Phase duration : 52 days
MTP : 30-32
Phase 16
--------
This phase started with Eclipse season (orbit 866 - 934).
During phase 16, there was also a Mosaic season (orbit 903 - 969) and
the Earth occultation season #7 (orbit 921 - 985).
Pendulum observations were frequently used. There was a joint
VIRTIS-SPICAV campaign of night side nadir airglow observations in
equatorial zone. There was good opportunity for SOIR nadir
observations.
SPICAV performed solar occultation and limb observations.
VMC performed monitoring, wind tracking on the day side, surface
imaging between solar occultations. Around orbit 967, they performed
night side imaging of Aphrodite Terra.
VIRTIS performed day side monitoring, limb observations together with
SPICAV. Later in the phase, VIRTIS also performed Mosaic at apocentre.
VeRa performed radio occultations.
VIRTIS suffered a failure of the M cooler on 27th October 2008. As a
consequence, from this date, there was no M-IR data.
Dates : September 23 - December 31, 2008.
Orbits : 886 - 985
Phase duration : 99 days
MTP : 32-35
Phase 17
--------
This phase started with the end of the Earth occultation season. On
orbit 1001 started a new eclipse season. The mission ended at the end
of the Eclipse season, at orbit 1045.
SPICAV observed day and night limbs and do Solar Occultations.
VMC observed night side imaging of the Aphrodite Terra (Ovda Regio,
Atla Regio, Sapas Mons, Ganis Chasma) and Rusalka Planitia.
VeRa did radio observation.
VIRTIS did observations every second orbit.
Dates : January 1 - March 1, 2009.
Orbits : 986 - 1045
Phase duration : days
MTP : 35-37
Phase 18
--------
This phase included inferior conjunction. There was no specific
season. It focuses on the Venus morning sector.
Every second orbit coordinated campaign of ground based observations
were organised.
SPICAV observed stellar occultations and day side tangential limbs.
VMC did wind tracking in the evening sector and night side imaging
of the western part of Aphrodite Terra (Ovda Regio, Monatum and Tellus
Tessera, Tahmina and Aino Planitia).
VIRTIS did terminator studies, limb observations with SPICAV and night
side surface observations with VMC.
VeRa did gravity experiment.
Dates : March 2 - May 4 , 2009.
Orbits : 1046 - 1109
Phase duration : days
MTP : 38-39
Phase 19
--------
This phase started with the Eclipse season (#11), at orbit 1110. It
ended when the Eclipse season ended, at orbit 1159. The day side
observations had good illumination conditions. The night side surface
observations were in eclipse.
SPICAV observed solar and stellar occultations as well as day side
tangential limbs.
VMC did day side observations and night side imaging of the Atlanta
and Rusalka Planitia and of Atahensik corona.
VIRTIS observed on the day side and limb observations with SPICAV.
Dates : May 5 - June 23 , 2009.
Orbits : 1110 - 1159
Phase duration : days
MTP : 40-41
Phase 20
--------
This phase started at the end of the Eclipse season (#11), at orbit
1160. It ended after the end of the Earth occultation season (#7) and
during the following Eclipse season (#12).
VeRa observed during the Earth occultation season and was given the
priority.
Night side surface targets: Llorona Planitia and Aphrodite Terra.
SPICAV did nadir observations around terminator (SO2), solar
occultation before pericentre, exospheric limb observation after
pericentre.
VMC observed night limb (O2 emission and surface) before
pericentre and day side nadir after pericentre. They observed in spot
pointing mode (see VEX_POINTING_MODE_DESC.TXT) for phase function
studies (study of the same place with different light conditions).
They also did VMC mosaic (see INSTRUMENT_MODE_DESC.TXT).
VIRTIS-H observed meridional cross-sections.
Dates : June 24 - Septembre 19 , 2009.
Orbits : 1160 - 1247
Phase duration : days
MTP : 41-44
Phase 21
--------
This phase started during the Eclipse season #12, at orbit 1248.
During the Eclipse season, the night side of the surface was observed.
At the end of the phase (orbits 1271-1275) there was the Drag Campaign
#2, meaning that the pericentre pass was devoted to the spacecraft
tracking by NNO and no observations within +/- 2 hours from the
pericentre were foreseen.
SPICAV SOIR was given the priority in pericentre observations.
SPICAV observed solar occultation. They did a campaign of nadir night
side observations (NO emission). They also observed exospheric limbs.
VMC observed day side nadirs. They did mosaic and spot pointing for
phase function studies (see phase 20).
VeRa did gravity measurements .
VIRTIS observed meridional cross sections of the night side.
Dates : September 20 - October 17 , 2009.
Orbits : 1248 - 1275
Phase duration : days
MTP : 45
Phase 22
--------
This phase did not contain any peculiar season. It ended just at
the beginning of the Earth occultation season (orbit 1335). The
observations focused on the morning sector of the planet. In orbit
1332, there was an OCM.
SPICAV followed their previous nadir night side campaign of NO
emission. They also did nadir observations of SO2 around terminator.
VMC did day side observations with off-track (see explanation above).
They also observed night limbs.
VIRTIS observed meridional cross-sections.
Dates : October 18 - December 16 , 2009.
Orbits : 1276 - 1335
Phase duration : 99 days
MTP : 46-47
Phase 23
--------
This phase started at the beginning of the Earth occultation season
#13 (orbit 1336). It contained both Earth and solar occultations , but
Earth could not be made due to conjunction. From orbit 1359 to 1378,
no science was performed due to telecommunication outage.
SPICAV did solar occultations and exospheric limbs.
VMC observed in pendulum mode and day side with off-track.
Pendulum: the observation points to Nadir, then out to space, then
back to Nadir, then back to space, etc., mimicking a pendulum
movement.
VIRTIS observed meridional cross sections.
VeRa did not observe due to proximity of the conjunction.
Dates : December 17 2009 - February 1 , 2010.
Orbits : 1336 - 1382
Phase duration : days
MTP : 48-49
Phase 24
--------
This phase had neither Earth nor solar occultations. It started at the
end of the eclipse season (orbit 1382) and ended with the start of the
new eclipse season (orbit 1447). The evening sector of the planet was
observed. Drag campaign #3 was scheduled for the orbits 1395-1457 and
was mainly contained in this phase. A pericentre OCM was scheduled in
the orbit 1402 and another one in the orbit 1430.
SPICAV observed stellar occultations and limbs with short pendulum
every 2 orbit.
VMC did pendulum, day side with off track and night limb observations.
VIRTIS observed meridional cross sections.
Dates : February 2 - April 6 , 2010.
Orbits : 1383 - 1446
Phase duration : days
MTP : 49-52
Phase 25
--------
This phase started with the eclipse season #14 at orbit 1447 and ended
with it at orbit 1499. During this phase started the Earth occultation
season #9 at orbit 1470. The night side surface of Venus was observed
in eclipse. Gravity campaign #11 was scheduled for orbits 1461, 1463
and 1465. An apocentre OCM was scheduled in the orbit 1458.
SPICAV observed stellar occultations, solar occultations and
exospheric limbs.
VMC observed on the day side (latitude tracking, VMC mosaic, spot
pointing for cloud phase function).
VIRTIS did meridional cross-sections.
VeRa performed radio occultations.
Dates : April 7 - May 29 , 2010.
Orbits : 1447 - 1499
Phase duration : days
MTP : 52-53
Phase 26
--------
This phase started at the end of the eclipse season #14 and ended at
the end of the Earth occultation season #9. A pericentre OCM was
scheduled in orbit 1500.
SPICAV observed stellar occultation, limbs, nadir around terminator
(SO2) and Earth.
VMC observed on the day side (latitude tracking, VMC mosaic, spot
pointing for cloud phase function).
VeRa did radio occultations.
VIRTIS-H observed meridional cross-sections.
Dates : May 30 - July 11 , 2010.
Orbits : 1500 - 1542
Phase duration : days
MTP : 53-55
Phase 27
--------
This phase focused on the morning sector of the planet. It started at
the end of the Earth occultation season #9 at orbit 1543 and ended at
orbit 1560.
The gravity campaign#12 initially scheduled was cancelled.
SPICAV observed stellar occultations and limbs.
They also observed nadir around terminator (SO2).
VMC observed the day side with off track to the day side (latitude
tracking, VMC mosaic, spot pointing for cloud phase function).
VeRa did radio occultations and the gravity campaign #12, during the
Earth occultation season.
VIRTIS-H observed meridional cross-sections.
Dates : July 12 - July 29 , 2010
Orbits : 1543 - 1560
Phase duration : 36 days
MTP : 55-56
Phase 28
--------
This phase included the eclipse season #15. Solar occultation occurred
after pericentre. Night surface observations in eclipse covered Thetis
Regio of Aphrodite Terra and Llorona and Niobe Planitia. At egress,
from eclispes the Artemis corona could be imaged.
Surface targets: Thetis Regio, Llorona and Niobe Planitia, Artemis
corona.
Instrument specific observations:
SPICAV did solar occultation observations after orbit 1571. There
was some joint SPICAM-SPICAV observations of hydrogen distribution
in solar corona.
VIRTIS did day latitude track (off pericentre), day side
spectroscopy (H) and night limb tracking surface (H) (pericentre).
VMC did day side monitoring (off pericentre), latitude tracking,
day limb tracking and night limb tracking (pericentre).
Dates : July 30 - September 13, 2010.
Orbits : 1561 - 1606
Phase duration : 45 days
MTP : 56-57
Phase 29
--------
This phase focused on the evening sector of the planet. Drag Campaing
#4 (1648-1654) occurred during this phase. After the Drag campaign,
the pericenre was raised to 340km. During this phase Venus approached
inferior conjunction. Surface imaging was possible either from
apocentre by VIRTIS or at close approach by VMC.
Intrument specific observations:
SPICAV did solar occultation (pericentre) and stellar occultations
(off pericentre).
SPICAV SOIR did calibrations and observed aeronomic emissions at
pericentre. SOIR calibrations consisted in 2 miniscans, 1 alignement
and 1 thermal performed in any part of the orbit outside the
eclipse.
VIRTIS did day latitude track full mosaic (off pericentre) and,
at pericentre, day spectroscopy (H) and night limb tracking (H).
VMC did day side monitoring and observe terminator (off pericentre)
and, at pericentre, latitude day tracking, day limb tracking, and
surface out of eclipse.
Dates : September 14 - November 18 , 2010.
Orbits : 1607 - 1671
Phase duration : 64 days
MTP : 57-59
Phase 30
--------
This phase included Eclipse season #16. It also coincided with
Akatsuki's arrival. Akatsuki is a Japanese spacecraft (JAXA) sent on
May 20, 2010 to study Venus Atmosphere dynamics. Unfortunately, the
Akatsuki experienced some problems during the orbit insertion
manoeuvre and failed to get captured in Venus orbit.
During this phase, solar occultation occurred before pericentre.
Surface Targets: Thesis, Ovda Regio of Aphrodite Terra, Tellus
Tessera, Niobe and Llorona Planitia, Artemis corona.
Instrument specific observations:
SPICAV SOIR did calibrations and was given priority in pericentre
observations.
SPICAV did stellar occultations (off peri) and observed exosperic
limb (peri).
VIRTIS did day latitude track (off peri) and, at pericentre, spectra
and night limb (M).
VMC did day side monitoring (off peri) and observed surface and limb
in eclipse at pericentre.
Dates : November 19, 2010 - January 16, 2011.
Orbits : 1672 -1731
Phase duration : 59 days
MTP : 60-61
Phase 31
--------
This phase included Earth occultation #10 and the beginning of eclipse
season #17. No solar occultation was possible during this phase.
Instrument specific observations:
SOIR did calibrations (off peri).
SPICAV observed stellar occultations (off peri) and at pericentre,
NO emission mapping in nadir, SO2 at terminator. There was also
joint SPICAV SPICAM observations.
VeRa did radio occultations.
VIRTIS did day latitude track off pericentre and at pericentre, limb
scans and day spectra.
VMC did day side monitoring off pericentre and observed morning
sector and evening sector at pericentre.
Dates : January 17 - March 22, 2011.
Orbits : 1732 - 1796
Phase duration : 64 days
MTP : 62-63
Phase 32
--------
This phase included Eclipse season #17.
Surface targets: Ovda and Thesis Regio, Manatum and Tellus Tessera,
Niobe and Tahmina Planitia.
Instrument specific observations:
SPICAV SOIR did calibrations (off peri) and solar occultations
(peri).
SPICAV did joint observation with SPICAM and stellar occultations
(peri).
VeRa did radio occultations.
VIRTIS did day latitude track off pericentre and spectra and limb
scan at pericentre.
VMC did day side monitoring off pericentre and, at pericentre,
day latitude tracking and surface observations.
Dates : March 23 - April 25 , 2011.
Orbits : 1797 - 1830
Phase duration : 33 days
MTP : 64-65
Phase 33
--------
This phase included Drag campaign #5. The pericentre was as low as 165
km and was raised to 290 km after the campaign.
Instrument specific observations:
SPICAV did joint observations with SPICAM off pericentre. At
pericentre SPICAV observed nadir for SO2 measurements, did limb
observations and stellar occultations.
VIRTIS did a full mosaic off pericentre and at pericentre observed
day spectroscopy and night limb.
VMC observed the terminator off pericentre and, at pericentre, the
surface and the limb.
Dates : April 26 - June 13 , 2011.
Orbits : 1831 - 1879
Phase duration : 48 days
MTP : 66-67
Phase 34
--------
This phase included both Earth occultation season #11 and eclipse
season #18. From orbit 1895 to 1907, Venus, Earth and Sun were on one
line. Radio and solar occultations sounded approximately the same
regions on Venus. This created a rare opportunity for co-located
soundings by VeRa and SOIR.
Surface targets: Ovda Region, Manatum and Tellus tessera.
Instrument specific observations:
SOIR performed calibrations off pericentre and solar occultations
(peri).
SPICAV did joint observations with SPICAM and stellar occultations
off pericentre and, at pericentre, observed zodacial light and
exospheric limb.
VIRTIS did off pericentre day latitude tracking. They observed limb
and did M spectral measurement at pericentre. They suffered a
failure in the H cooler on June, 13th 2011. From this date, there
was no H data.
VMC did day side monitoring off pericentre and, at pericentre, they
observed the limb and the surface.
Dates : June 14 - August 26 , 2011.
Orbits : 1880 - 1953
Phase duration : 73 days
MTP : 67-69
Phase 35
--------
This phase included Drag campaign #6.
Instrument specific observations:
SOIR performed off pericentre calibrations.
SPICAV did off pericentre joint observation with SPICAM. They also
did stellar occultations off pericentre. At pericentre they did SO2
measurements in nadir modes and at terminator.
VIRTIS did day latitude track (off peri). At pericentre they did
limb scans and spectral measurements.
VMC did day side monitoring at terminator (off peri) and day
latitude tracking at pericentre.
Dates : August 27 - October 24 , 2011.
Orbits : 1954 - 2012
Phase duration : 58 days
MTP : 70-71
Phase 36
--------
This phase included Eclipse season #19 and the first half of Earth
occultation #12.
Surface targets: Manatum Tessera, Tahmina Platinia, Tellus Tessera,
Niobe Planitia and Ovda regio.
Instrument specific observations:
SOIR performed off pericentre calibrations and solar occultations at
pericentre.
SPICAV did joint observations with SPICAM and stellar occultations
off pericentre. At pericentre, they observed zodacial light.
VIRTIS did off pericentre day latitude track. At pericentre, they
did limb scans, measure day spectra.
VMC did off pericentre day side monitoring. At pericentre, they did
day latitude tracking and observed the surface.
Dates : October 25 - December 04 , 2011.
Orbits : 2013 - 2053
Phase duration : 40 days
MTP : 72- 73
Phase 37
--------
This phase included the second half of Earth occultation season #12.
Instrument specific observations:
SPICAV did tangential limb and stellar occultations at pericentre.
VeRa did radio occultations.
VIRTIS did off pericentre day latitude track and full mosaic. At
pericentre, they did day spectroscopy and night limb tracking.
VMC did day side monitoring off pericentre. At pericentre they did
day latitude tracking and observed the surface.
Dates : December 5, 2011 - January 07 , 2012.
Orbits : 2054 - 2087
Phase duration : 33 days
MTP : 74
Phase 38
--------
This phase included Drag campaign #7. The pericentre was as low as
165km.
Instrument specific observations:
SOIR performed calibration off pericentre.
SPICAV did off pericentre stellar occultations. At pericentre, they
observed nadir mode at terminator and measured aeronomic emissions.
VIRTIS did day side tracking off pericentre, 2 full mosaics. At
pericentre, they did limb tracking.
VMC observed the surface, the limb and did day latitude tracking at
pericentre.
Dates : January 8, 2012 - February 4, 2012
Orbits : 2088 - 2115
Phase duration : 27 days
MTP : 75
From this phase, there were two new observation types defined for
SPICAV and SPICAV SOIR . The first one were observations in eclipse of
the NO airglow using inertial mode. The spacecraft is held in inertial
mode such that the observed point sweeps a wide range of latitudes
while the spacecraft is in eclipse. The second one done by SOIR
intended to observe light reflected from the dayside cloud top.
Phase 39
--------
This phase included the start of an eclipse season in orbit 2119. The
solar occultation occured before pericentre. Phase 39 and 40 were an
opportune time for two campaigns. Before pericentre (nightside), every
other orbit was allocated to VIRTIS-MVIS night limb search for
airglow. After pericentre (dayside), this MTP could be used for SPICAV
dayside limb observations of airglow.
Surface targets: Ishtar Terra in the Northern Hemisphere; Central
Eistla Regio, Lada Terra (Southern hemisphere),
Bereghinia Planitia (28 deg E, 39 deg N).
VIRTIS: Mosaic from apocentre, limb track airglow observations
SPICAV: Sub-solar point observation, for Cross Polarization
calibration, Zodiacal Light Observation during eclipse.
SOIR: nadir observation.
SPICAV and VIRTIS: nadir observations at pericentre (optimised for
nadir absorption spectroscopy.
VMC: phase function observations, mosaics of dayside at pericentre.
Dates : February 5, 2012 -March 3, 2012
Orbits : 2116 - 2143
Phase duration : 27 days
MTP : 76
Phase 40
--------
The entire phase was in eclipse season. The long Earth occultation
season started at the end of this phase (in orbit 2167).
Surface targets: Ishtar Terra, Bell Regio (e.g. Tepev Mons),
E. Eistla Regio.
VIRTIS: M-VIS limb-track observations (night side in eclipse).
SPICAV: Stellar occultation, VEX-SOHO joint observations.
SOIR: Solar occultations.
VeRa: Radio occultations.
Dates : March 4, 2012 - March 31, 2012
Orbits : 2144 - 2171
Phase duration : 27 days
MTP : 77
Phase 41
--------
The eclipse season ended in orbit 2178. The long Earth occultation
season continued throughout the phase.
Atmospheric Drag Campaign #8 occurred during this phase.
Surface targets: Ovda Regio, Tellus Tessera.
VeRa: Ingress passes probing low latitudes, radio occultation passes
in pure Earth-pointing combined with the drag passes (TRQ only).
VIRTIS-M-VIS: search for airglow, global spectro-imaging from
apocentre.
SPICAV: Stellar occultation.
No SOIR observation.
Dates : April 1, 2012 - April 28, 2012
Orbits : 2172 - 2199
Phase duration : 27 days
MTP : 78
Phase 42
--------
The long Earth occultation season continued throughout the phase. The
beginning of the phase (orbits 2196-2207) saw continuation of
Atmospheric Drag experiment #8. Almost every pericentre pass was
reserved for radio science.
Surface targets: Lada Terra.
VeRa: occultations during drag passes in pure Earth-pointing mode,
from orbits 2204-2224 a campaign of consecutive VeRa ingress
occultations on every orbit probed repeatedly the same latitude
(around 30-35 deg S).
VMC: meteor showers (TBC)
VIRTIS-M-VIS: cloud morphology imaging in spot-tracking mode
Dates : April 29, 2012 - May 26, 2012
Orbits : 2200 - 2227
Phase duration : 27 days
MTP : 79
Phase 43
--------
This MTP included the inferior conjunction, at which a transit of
Venus occurred (6 June 2012, 01:29:35 UT, Orbit 2238). The long Earth
occultation season continued throughout the whole of this phase.
Eclipse season started on June, 6th, orbit 2238. This TMP contained
the Venus Transit (June 6th 2012).
Special observations due to Venus Transit:
- VIRTIS off pericentre observations.
- SOIR grazing occultation
- Limb imaging from SPICAV
- VMC sufferred an anomaly that shut down the instrument on 4 June
2012, Orbit 2236 at 01:42Z.
- SPICAV UV imaging of the Sun immediately prior to the transit day,
in Orbit 2237 (05-Jun-2012, DOY157), for cross calibration with
ISS/SOLSPEC
Surface targets: Ishtar Terra, C. Eistla Regio, Bereghinia Planitia,
Lada Terra in the S hemisphere.
VIRTIS: high resolution morphology observation close to pericentre,
atomic oxygen airglow monitoring before and after each eclipse season.
VeRa: activity after orbit 2238, start of eclipse season.
SPICAV: SPICAM/SPICAV observations near apocentre at orbits 2248-2250
Dates : May 27, 2012 - June 23, 2012
Orbits : 2228 - 2255
Phase duration : 27 days
MTP : 80
Phase 44
--------
Dates : June 24, 2012 - July 21, 2012
Orbits : 2256 - 2283
Phase duration : 27 days
MTP : 81
Phase 45
--------
Dates : July 22, 2012 - August 18, 2012
Orbits : 2284 - 2311
Phase duration : 27 days
MTP : 82
Phase 46
--------
Dates : August 19, 2012 - September 15, 2012
Orbits : 2312 - 2339
Phase duration : 27 days
MTP : 83
Phase 47
--------
Dates : September 16, 2012 - October 13, 2012
Orbits : 2340 - 2367
Phase duration : 27 days
MTP : 84
Phase 48
--------
Dates : October 14, 2012 - November 10, 2012
Orbits : 2368 - 2395
Phase duration : 27 days
MTP : 85
Phase 49
--------
Dates : November 11, 2012 - December 08, 2012
Orbits : 2396 - 2423
Phase duration : 27 days
MTP : 85
Eclipse season
==============
Eclipse Dates
Season #
-------------------------------------
1 | 16 Apr 2006 - 31 May 2006
2 | 6 Aug 2006 - 13 Sep 2006
3 | 16 Nov 2006 - 10 Jan 2006
4 | 17 Mar 2007 - 26 Apr 2007
5 | 29 Jun 2007 - 21 Aug 2007
6 | 27 Oct 2007 - 9 Dec 2007
7 | 9 Feb 2008 - 1 Apr 2008
8 | 6 Jun 2008 - 20 Jul 2008
9 | 23 Sep 2008 - 10 Nov 2008
10 | 16 Jan 2009 - 28 Feb 2009
11 | 5 May 2009 - 23 Jun 2009
12 | 27 Aug 2009 - 17 Oct 2009
13 | 17 Dec 2009 - 1 Feb 2010
14 | 7 Apr 2010 - 29 May 2010
15 | 30 Jul 2010 - 13 Sep 2010
16 | 18 Nov 2010 - 10 Jan 2011
17 | 13 Mar 2011 - 25 Apr 2011
18 | 29 Jun 2011 - 25 Aug 2011
19 | 25 Oct 2011 - 04 Dec 2011
20 | 08 Feb 2012 - 07 Apr 2012
21 | 06 Jun 2012 - 15 Jul 2012
22 | 19 Sep 2012 - 19 Nov 2012
23 | 18 Jan 2013 - 23 Feb 2013
------------------------------------
Earth occultation Season
========================
Occultation Dates
Season #
-------------------------------------
1 | 11 Jul 2006 - 30 Aug 2006
2 | 22 Nov 2006 - 31 Jan 2007
3 | 26 Apr 2007 - 1 Jul 2007
3a | 4 Sep 2007 - 18 Sep 2007
4 | 4 Jan 2008 - 13 Mar 2008
5 | 5 Jun 2008 - 1 Aug 2008
6 | 28 Oct 2008 - 31 Dec 2008
7 | 16 Jul 2009 - 19 Sep 2009
8 | 10 Dec 2009 - 8 Feb 2010
9 | 30 Apr 2010 - 11 Jul 2010
10 | 17 Jan 2011 - 22 Mar 2011
11 | 14 Jun 2011 - 25 Aug 2011
12 | 15 Nov 2011 - 06 Jan 2012
13 | 27 Mar 2012 - 06 Oct 2012
14 | 30 Dec 2012 - 15 Feb 2013
------------------------------------
Solar conjunction (superior)
============================
Solar Dates
Conjunction #
-------------------------------------
1 | 17 Oct 2006 - 8 Nov 2006
2 | 29 May 2008 - 19 Jun 2008
3 | 26 Dec 2009 - 28 Jan 2010
4 | 06 Aug 2011 - 26 Aug 2011
-------------------------------------
Drag Campaign
=============
DC# | Dates |
---------------------------------------
1 | 01 Aug 2008 - 22 Aug 2008 |
2 | 12 Oct 2009 - 18 Oct 2009 |
3-1 | 22 Feb 2010 - 28 Feb 2010 |
3-2 | 11 Apr 2010 - 16 Apr 2010 |
4(TBC)| 13 Oct 2010 - 25 Oct 2010 |
5(TBC)| 23 May 2011 - 03 Jun 2011 |
6(TBC)| 13 Sep 2011 - 24 Sep 2011 |
7(TBC)| 08 Jan 2012 - 19 Jan 2012 |
---------------------------------------
Gravity
=======
Grav# | Dates |
---------------------------------------
1 | 01 Sep 2006 - 10 Sep 2006 |
2 | Cancelled |
3 | 27 Dec 2007 - 02 Jan 2008 |
4 | 09 Mar 2009 - 15 Mar 2009 |
5 | 21 Mar 2009 - 27 Mar 2009 |
6 | 15 Apr 2009 - 19 Apr 2009 |
7 | 27 Apr 2009 - 01 May 2009 |
8 | 25 May 2009 - 31 May 2009 |
9 | 25 Jun 2009 - 01 Jul 2009 |
10 | 01 Oct 2009 - 07 Jul 2009 |
11 | 21 Apr 2010 - 25 Apr 2010 |
12 | 14 Jul 2010 - 20 Jul 2010 |
---------------------------------------
Spacecraft events
=================
Event | Dates |
---------------------------------------------------------------|
Launch | 09 Nov 2005 |
Earth Moon observations | 22/23 Nov 2005 |
Pointing Test 1 | 27 Nov 2005 - 04 Dec 2005 |
Interference Test | 14 Dec 2005 - 15 Dec 2005 |
Pointing Test 2 | 16 Jan 2006 - 21 Jan 2006 |
VOI | 11 Apr 2006 |
Capture Orbit Observation 0 | 12 Apr 2006 |
Capture Orbit Observation 1 | 13 Apr 2006 |
Capture Orbit Observation 2 | 14 Apr 2006 |
Capture Orbit Observation 3 | 16 Apr 2006 |
Capture Orbit Observation 4 | 17 Apr 2006 |
Capture Orbit Observation 5 | 19 Apr 2006 |
First Operational orbit | 07 May 2006 |
(17th Apocentre) | |
Case Commissioning Start | 14 May 2006 |
Extended Case Commissioning Start | 24 May 2006 |
Nominal Science Start MTP002 | 04 Jun 2006 |
Safe Mode 01 | 13 Jun 2006 |
Mission Commissioning Results | 04 Jul 2006 |
Review | |
Safe Mode 02 | 25 Aug 2006 18:15 UTC |
Safe Mode 03 | 22 Sep 2006 19:24 UTC |
Safe Mode 04 | 27 Sep 2006 04:37 UTC |
Safe Mode 05 | 09 Oct 2006 04:20 UTC |
VIRTIS-H and VIRTIS-M shutdown | 13 Aug 2007 |
due to cooling Motors | |
VIRTIS-M restarted | 31 Aug 2007 |
Payload Off due to SADE-A | 25-27 Aug 2007 |
misalignment | |
VIRTIS-H restarted | 04 Nov 2007 |
Safe Mode 06 | 27/28 Jan 2008 |
VIRTIS-M cooler failure | 27 Oct 2008 23:58 |
VIRTIS-M unit resumed non cooler | 28 Jan 2009 |
operations in only the | |
visible channel | |
VMC SSMM overflow | 11 March 2009 |
Safe Mode 07 | 30 Jul 2010 02:54 UTC - |
| 31 Jul 2010 16:03 UTC |
VIRTIS-H cooler failure | 13 Jun 2011 22:33 UTC - ? |
Operations Shutdown due to Star | 7 Mar 2012 12:00 UTC - |
Tracker blindness (Solar Flare) | 12 Mar 2012 13:26 UTC |
----------------------------------------------------------------
Moreover, about every 6 months a SSMM problem (named SCET problem)
occurs for about 15 minutes. During this time, the spacecraft cannot
record data and the data is lost. This problem does not really affect
archive but it is put in the mission catalog as a general information.
|
| MISSION_OBJECTIVES_SUMMARY |
Mission Objectives Overview
===========================
Background
----------
The first explorations (1962-1985) of Venus showed that the planet
was hidden behind a curtain of dense clouds. Despite of the
exploration by more than 20 spacecrafts, the studies gave basic
knowledge of the conditions on the planet but generated more
questions concerning the atmospheric composition, chemistry,
structure dynamics, surface-atmosphere interactions, atmospheric and
geological evolution, and the plasma environment.
The scientific objectives include atmospheric physics, subsurface
and surface studies, investigation of the plasma environment and
interaction of the solar wind with the atmosphere. For clarity, the
atmosphere has been divided into three parts: lower atmosphere (0-60
km), middle atmosphere (60 - 110 km), and upper atmosphere (110 - 200
km).
The physics, methods of investigation, and scientific goals are quite
different for each atmospheric region. However they all can be
studied by a multipurpose remote sensing and in situ payload in the
framework of the proposed orbiter mission.
Lower atmosphere and cloud layer (0-60km)
-----------------------------------------
Structure
---------
Previous studies showed that the temperature structure below 30 km is
quite constant all over the planet. However, the temperature
structure in the lower scale height is virtually unknown. Mapping the
regions of high elevation in sub-micron spectral 'windows' at the
nightside will determine the surface temperature as a function of
altitude (Meadows and Crisp (1996)). Assuming this is equal to the
near-surface air temperature, this will allow a determination of the
thermal profile and lapse rate in the 0-10 km range and an
investigation of its degree of static stability, constraining the
dynamics and turbulence in this region. The thermal structure above
35 km altitude will be obtained from radiooccultations with high
vertical resolution.
(i)-a Thermal profile and lapse rate in the 0-10 km rage.
(i)-b dynamics and turbulence in the 0-10 km range.
(i) is done by mapping the regions of high elevation in sub-micron
spectral windows at the nightside.
(ii) thermal structure above 35 km altitude by radioocculatations
with high vertical resolution.
Composition
-----------
The study of the lower atmosphere composition by means of
spectroscopy in the near IR transparency 'windows' is one of the main
goals of the Venus Express mission.
More specific objectives include abundance measurements of H2O, SO2,
COS, CO, H2O, HCl, and HF and their horizontal and vertical
(especially for H2O) variations:
a/ to significantly improve our understanding of the chemistry,
dynamics, and radiative balance of the lower atmosphere,
b/ to search for localized volcanic activity.
Cloud layer
-----------
Venus is shrouded by a 20 km thick cloud layer whose opacity varies
between 20 and 40 in the UV, visible and infrared. The clouds are
almost featureless in visible light but display prominent markings in
the UV-blue spectral region. Earlier observations showed that at
least the upper cloud consists of micron size droplets of 75% H2SO4,
which is produced by photochemical reactions at the cloud tops. The
physical and chemical processes forming the lower clouds are
virtually unknown, including major problems like (1) the nature of
the UV-blue absorber which produces the features observed from space
and absorbs half of the energy received by the planet from the Sun,
and (2) the origin of the large solid particles detected by the
Pioneer-Venus probe.
The remote sensing instruments on Venus Express will sound the
structure, composition, dynamics, and variability of the cloud layer,
including:
- Cloud and haze structure and opacity variations;
- Distribution and nature of the UV-blue absorber;
- Measurements of atmospheric composition which constrain models of
cloud formation and evolution.
Greenhouse effect
-----------------
The high surface temperature of about 735 K results from the powerful
greenhouse effect created by the presence of sulphuric acid clouds
and certain gases (CO2, H2O, SO2) in the atmosphere (see
[CRISP&TITOV1997]). Less than 10% of the incoming solar radiation
penetrates through the atmosphere and heats the surface, but thermal
radiation from the surface and lower atmosphere has a lower
probability of escape to space due to the strong absorption by gas
and clouds. The result is about 500K difference between the surface
temperature and that of the cloud tops, an absolute record among the
terrestrial planets.
The measurements of outgoing fluxes over a broad spectral range,
combined with temporarily and latitudinally resolved cloud mapping
and high resolution spectroscopy in the near IR windows will give an
insight into the roles of radiative and dynamical heat transport, and
the various species, in the greenhouse mechanism.
Atmospheric dynamics
--------------------
The dynamics of the lower atmosphere of Venus is mysterious. Previous
analysis showed that the atmosphere is involved in zonal retrograde
super-rotation with wind velocities decreasing from ~100 m/s at the
cloud tops to almost 0 at the surface. At the same time, there
appears to be a slower overturning of the atmosphere from equator to
pole, with giant vortices at each pole recycling the air downwards.
Additional questions include:
(1) whether the meridional circulation is one enormous 'Hadley' cell
extending from the upper atmosphere to the surface, or a stack of
such cells, or something else altogether;
(2) how the polar vortices couple the two main components of the
global circulation and why they have such a complex shape and
behaviour;
(3) what the observed (and observable) distributions of the minor
constituents in Venus'atmosphere, including the clouds, are telling
us about the motions
The Venus Express spacecraft orbiting every 10-15 hours and imaging
the poles both in the thermal infrared wavelengths, sensitive to the
emission from the cloud tops, and the near-IR 'windows', which probe
much deeper, will allow the production of time- and spatially-
resolved movies which would reveal much more information about the
behaviour of the Venusian polar vortices.
The Venus Express spacecraft will globally track the time and space
evolution of the clouds with precision over an extended period of
time.
Lightning
---------
The Venus clouds consist, at least in part, of sulphuric acid
particles, which have the ability to form highly charged droplets and
offer the potential of lightning. The nature and occurrence, and even
existence of lightning on Venus remains a topic of much debate
[GREBOWSKYETAL1997]. Resolving this debate with new data is important
both for understanding how the atmospheres of the terrestrial planets
become electrified and discharge and to determine if lightning is
important in the chemistry of the Venus atmosphere.
Venus Express will provide a long-term set of electromagnetic and
optical observations to determine the strength of the flashes and
their rates of occurrence, and hence to investigate the nature of
lightning on Venus.
Middle atmosphere (60-110 km)
-----------------------------
The Venera and Pioneer Venus orbiters observed this region in the UV
and thermal infrared, but with relatively poor coverage in spectral
range, latitudes and local solar time [LELLOUCHETAL1997].
Temperature
-----------
The temperature structure of the middle atmosphere shows significant
latitudinal variability which is probably driven by the dynamics but
remain poorly understood. Systematic monitoring of the upper
mesospheric (70-100 km) temperature field would help to unfold the
nature of cyclostrophic balance and the highly variable zonal winds
above the cloud tops.
Composition and chemistry
-------------------------
The mesosphere is the region where photochemical dissociation of CO2
and SO2 occurs, followed by cycles of carbon dioxide recombination
and formation of sulphuric acid. The mesospheric chemistry is
described by a chain of reactions that involves HOx, ClOx, SOx, and
Cx. H2O exhibit a remarkable variability in the mesosphere. Pioneer
Venus found a high concentration of water vapour in a localized
region in the mid-afternoon local time, perhaps due to a dynamical
phenomenon, in which convection driven by a local heating maximum
transports relatively moist air from beneath. A steady decline of SO2
from about 400 ppb to ~100 ppb at the cloud tops was observed to
occur between 1979 and 1989 [ESPOSITOETAL1997], possibly attributable
to a volcanic eruption at the end of the seventies. Also the SO2
mixing ratio seems to increase towards the poles.
The water vapour and sulfur dioxide should be studied in more detail
to understand both chemistry and dynamics of the mesosphere, as well
as the processes of cloud formation.
Dynamics
--------
The middle atmosphere is a transition region between the zonal
super-rotation regime in the lower atmosphere and solar-antisolar
circulation in the upper atmosphere, but how the transition occurs is
virtually unknown. The lower mesosphere is characterized by
deposition of significant amount of solar energy due to the presence
of unknown UV-blue absorber in the upper cloud (67-60 km). Tracking
the motions of the UV features from orbit is a powerful tool to study
the global circulation and wave phenomena in the lower mesosphere.
Mesospheric dynamics was also studied indirectly by Venera-15 and
Pioneer Venus orbiters that measured the 3-D temperature field with
subsequent derivation of zonal wind field assuming cyclostrophic
balance [LELLOUCHETAL1997, ESPOSITOETAL1997]. The zonal wind is
dominated by the strong midlatitude jet with speeds up to 150 m/s.
This jet located at ~50 N in the vicinity of the cloud tops shows
tidal variability. Two weaker jets were also identified at ~85 km and
~65 km.
The O2 airglow in the near IR (1.27 m) and visible ranges (0.4-0.8 m)
are formed from the recombination of atomic O produced on the dayside
from the CO2 photolysis at 100-120 km and transported to the night
side by the subsolar-to-antisolar flow. They nominally probe the
95-110 km region (IR airglow) and 100-130 km region (visible
airglow), and their intensities and spatial distributions are
strongly dependent on the mesospheric/ thermospheric circulation, and
specifically on the zonal wind profile, the Rayleigh friction
controlling the subsolar-to- antisolar flow, and the nightside eddy
diffusion coefficient.
The Venus Express orbiter will investigate the mesosphere by means of
global, simultaneous, and spatially resolved spectroscopic
observations ranging from UV to thermal IR and will:
- Study the wind and dynamic phenomena by tracking the motions of UV
cloud features;
- Measure the 3-D temperature and thermal wind fields;
- Study the abundance of SO2,SO, H2O,HCl, CO and other species;
Mapping the O2 infrared and visible airglow as dynamical tracer.
Upper atmosphere (110-200 km)
-----------------------------
Structure and composition
-------------------------
Our knowledge of the structure of Venus thermosphere remains
incomplete because:
(i) in-situ measurements provide limited spatial sampling
(ii) airglow features typically probe broad (15-20 km range) vertical
regions, i.e. have poor vertical resolution
(iii) most of the information is restricted to equatorial latitudes.
Thus, a global characterization of density and temperature structure
is still needed.
Dynamics
--------
The large day-to-night temperature (and corresponding pressure)
gradients in the thermosphere were expected to drive very strong
(nearly 400 m/s) subsolar-to-antisolar winds. However, from the
available data (neutral density and temperature contrasts, UV,
visible, and IR airglow maps), the global circulation of the Venus
upper atmosphere is inferred to be much weaker, and can be decomposed
into two distinct flow patterns :
(1) a generally stable subsolar-to- antisolar (SS-AS) circulation
cell driven mostly by solar EUV/UV heating
(2) an asymmetric retrograde superrotating zonal (RSZ) flow that
seems to vary greatly over time [BOUGHERETAL1997, KASPRZAKETAL1997].
The processes responsible for maintaining and driving variations in
the thermospheric winds are still not well understood or quantified.
It is apparent that some type of deceleration mechanism, perhaps the
breaking of upward propagating gravity waves, is necessary to slow
the upper atmospheric winds, but a viable gravity wave drag mechanism
must still be found.
Minor constituents with intermediate chemical and photochemical
lifetimes yield clues about the atmospheric dynamics at different
levels.
The 3D modeling tool used to examine the density, temperature,
airglow distribution is currently unable to reproduce the observed.
The modeling task would be much improved if simultaneous temperature,
density and wind measurements could be made above 100 km.
The key science problems related to the thermosphere are summarized
as follows:
(1). What are the processes responsible for maintaining (and driving
variations in) the subsolar-to-antisolar (symmetric) and
superrotating (asymmetric) global winds in the Venus upper
atmosphere?
(2). What is the self-consistent (unique) solution of the global
wind, temperature, and density variations of the Venus thermosphere?
Venus Express will address these questions by:
(i) Measurements of the atmospheric structure up to 180 km with high
vertical resolution from solar/stellar occultations, especially in
middle and high latitudes;
(ii) Mapping the airglows of O2, NO, O, and H as global circulation
tracers;
(iii) Studying the dynamical processes that link the middle and upper
atmosphere (tides, planetary and gravity waves, etc.)
Plasma environment and escape processes
---------------------------------------
The study of escape processes from the upper atmosphere has direct
implications for the origin and evolution of the Venus atmosphere.
How did the atmosphere evolve under the combined effects of escape
and interaction with the solid planet? The insignificant amount of
water is possibly explained by intense hydrogen escape at early
epochs. Similarly, the lack of molecular oxygen in the present Venus
atmosphere requires extremely strong escape in the past and/or
massive oxidation of surface material. Current understanding of these
processes based on relative abundance of noble gases and isotopic
ratios is rather poor.
Water: Hydrogen and Deuterium
-----------------------------
Venus Express will address the problems of atmospheric escape and
plasma environment by :
- in situ measurements of the energetic neutral atoms, ions,
electrons, and magnetic field and inference of escape rates;
- active radar sounding of the vertical structure of the topside
ionosphere;
- high-resolution spectroscopic observations of CO2 and H2O to derive
ratios of C, O, and H isotopes from the cloud tops up to ~200 km;
- Remote sounding of the solar wind turbulence.
Studies of the atmospheric escape via in situ measurements are
inherently limited by spatial coverage of a spacecraft and can be
performed only statistically. Only though global imaging techniques
such as ENA imaging by ASPERA, instantaneous observations of the
global distribution of the escaping plasma can be provided
[WILLIAMSETAL1992].
Magnetic field measurements will be helpful to interpret the in situ
plasma measurements and associated ionospheric structures below. The
investigation of vertical distribution of species in the exosphere
and plasma/magnetic field/ energetic neutral atoms environment near
Venus is very important in order to understand the evolution of
terrestrial atmospheres and to understand better what was the Earth's
environment during the epochs of weak magnetic field.
Surface and surface-atmosphere interaction
------------------------------------------
Geology
-------
The Magellan images surprisingly revealed that Venus is among the
most geologically active planets in the Solar System. Volcanic
activity and tectonics have strongly affected the Venusian surface
[SOLOMONETAL1992] forming highly deformed plateau (Tesserae) and large
lowlands (Planitiae).
Magellan raised new mysteries about the geological evolution of the
planet:
- What was the global geodynamic style within the last 0.5-1 b.y. of
the geologic history of this planet?
- Were the observed tectonic structures formed in global-wide pulses
with a specific strain environment or did tectonic resurfacing occur
in episodes more distributed in space and time?
- What are the volumes of old and recent volcanism?
- What were the rates of volcanism in different geologic epochs?
- Is there ongoing volcanic and tectonic activity?
- What is the true scale of exogenic processes controlling, at least
partly, surface microrelief?
These questions arise in part because Magellan and previous missions
could not determine the sub-surface relations of the geological
bodies due to using the frequencies that limited the measured
characteristics of the surface to certain scales. The Venus Express
radio science investigation VeRa meet these challenges and will
strongly complement the Magellan observations. The mission will
perform subsurface sounding of the Venusian landforms to:
1) outline the internal 3D geometry of tectonic and stratigraphic
relationships between geological bodies,
(2) provide new data on surface properties,
(3) provide new altimetry data complementing Magellan imagery.
Surface properties and surface-atmosphere interactions
------------------------------------------------------
The surface of Venus is geologically young and the presence of
sulphuric acid clouds together with the large abundance of SO2
suggests the possibility of current volcanic activity. Observations
in the sub-micron spectral 'windows' will search for regions of
volcanic activity through enhanced surface temperatures and possibly
enhanced gaseous absorption (SO2, H2O, HCl, for instance). Measuring
the abundance of these gases in the lower atmosphere will also
provide constrains on the models of the surface-atmosphere
interaction. In particular, reactive gases, such as HF and HCl, are
thought to be buffered by chemical assemblages on the Venusian
surface.
Monitoring the HCl abundance and searching for possible horizontal
variations through nightside observations at 1.7 m will permit to
check the effectiveness of this chemical buffering. If variations
were detected, they would point to dynamical effects associated with
unknown atmospheric chemistry and would thus have strong implications
on the halide chemistry and mineralogy.
Venus Express will significantly contribute to this problem by
providing high-resolution spectroscopic, spectro-imaging, and mapping
in the near-IR spectral windows.
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