Mission Overview
  ================
    Chandrayaan-1, the first Indian mission to Moon, was designed to carry out
    high resolution remote sensing studies of the Moon to further our
    understanding of its origin and evolution.  At 00:52 UT on 22 October
    2008, the Indian Space Research Organization (ISRO) launched Chandrayaan-1
    on-board an upgraded Polar Satellite Launch Vehicle (PSLV-C11) from the
    Satish Dhawan Space Center (SDSC) in Sriharikota located along the
    southeast coast of India.  The PSLV-C11 injected the orbiter spacecraft
    into an eleven-hour elliptical transfer orbit around the Earth on 23
    October 2008.
 
    The launch was planned such that the Moon is at one of its nodes when the
    spacecraft arrives.  In order to have multiple launch opportunities every
    month and to contain burn errors, a phasing loop strategy with multiple
    loops and five Earth bound maneuvers was adopted.  The injection
    parameters are as follows:
 
      Semi-major axis : 17971.73 km
      Eccentricity    : 0.63094
      Inclination     : 17.9112 deg
      Perigee height  : 254.457 km
      Apogee height   : 22932.741 km
 
    From 25 October through 4 November 2008 several maneuvers were performed
    to put the spacecraft into a lunar transfer trajectory, and on 8 November
    Chandrayaan-1 was successfully inserted into a lunar orbit.  By 12
    November the spacecraft had reached its intended 100-km circular polar
    orbit for chemical, mineralogical, and photo-geologic mapping of the Moon
    by its eleven on-board instruments; scientific observations were scheduled
    to continue at this altitude for two years.  The details of the five Earth
    bound maneuvers, lunar insertion maneuver, and circularizing maneuvers at
    the Moon are provided here:
 
     .----------------------------------------------------------------------.
     |        | Central | Perigee | deltaV |  Dur   | Post Maneuver Orbit   |
     | Burn   |  Body   | Number  |  (m/s) |  (s)   | perigee x apogee (km) |
     |--------|---------|---------|-----------------------------------------|
     | EBN #1 |  Earth  |    4    | 344.43 |   -    |   299.2 x  37908.1    |
     | EBN #2 |  Earth  |    8    | 328.14 | 912.36 |   336.3 x  74715.6    |
     | EBN #3 |  Earth  |    9    | 221.69 | 567.73 |   347.8 x 165015.1    |
     | EBN #4 |  Earth  |   10    |  77.17 | 192.18 |   459.4 x 266612.9    |
     | EBN #5 |  Earth  |   11    |  60.70 | 147.68 |   972.8 x 379859.2    |
     | TCM    |  Earth  |         |   0.82 |   5.59 |   802.8 x 378499.2    |
     |--------|---------|---------|--------|--------|-----------------------|
     | LOI    |  Moon   |    -    | 366.96 | 817.07 |   507.9 x   7510.1    |
     | LBN #1 |  Moon   |    -    |  26.60 |  56.95 |   197.8 x   7507.1    |
     | LBN #2 |  Moon   |    -    | 448.20 | 868.00 |   183.0 x    255.2    |
     | LBN #3 |  Moon   |    -    |  17.03 |  31.30 |   103.3 x    253.9    |
     | LBN #4 |  Moon   |    -    |  32.13 |  58.60 |   101.9 x    102.8    |
     .----------------------------------------------------------------------.
 
    From 16 to 19 May 2009 the Chandrayaan-1 spacecraft was raised to a 200-km
    orbit to keep the temperature of the orbiter down after star trackers
    failed.  This change enabled further studies of orbital perturbations and
    gravitational field variations and imaging of the lunar surface with a
    wider swath. After completing more than 3400 orbits of the Moon in 312
    days and providing a large volume of data from its suite of sensors that
    met most mission objectives, communication with the spacecraft was
    abruptly lost around 20:00 UT on 28 August 2009.  ISRO officially
    terminated the mission on 31 August 2009.
 
 
  Instruments and Experiments
  ===========================
 
    TMC
    ---
      Terrain Mapping Camera (TMC) is designed to image in the panchromatic
      spectral band of 0.5 to 0.75 microns with a stereo view in the forward,
      nadir, and aft directions of the spacecraft movement and a base-to-
      height ratio of 1.  The swath of the instrument is 20 km.  The key
      features of TMC are:
 
        Spatial sampling  : 5 x 5 sq.m (from 100-km orbit)
        Swath             : 20 km
        Spectral band     : Panchromatic (0.5 to 0.75 micro-m)
        Stereo mode       : Along track triplet, B/H = 1
        No. of gains & exposure : 4 each
        Square wave response    > 25
        Signal to noise ratio   > 350
 
      The instrument is from Space Applications Centre, Ahmedabad, India.
 
    HySI
    ----
      The Hyper Spectral Imager (HySI), operating in the visible and near
      infrared spectral region, is one of the three imaging instruments on-
      board the Chandrayaan-1 spacecraft for mineralogical study of the Moon.
      HySI is designed to map the entire lunar surface in 64 contiguous bands
      in the visible and near infrared (VNIR: 421 to 964 nm) with a spatial
      sampling of 80 m.  A wedge filter is employed for the spectral
      separation, and the image is mapped onto an area detector.  The detector
      output is processed in the front-end electronics to generate the 64-band
      with 12-bit quantization. The key features of HySI are:
 
        Spatial sampling        : 80 x 80 sq.m (from 100-km orbit)
        Swath                   : 20 km
        Spectral range          : 461 to 964 nm
        No: of spectral bands   : 64 continuous
        No: of gains            : 2
        No: of exposure setting : 4
        Quantization            : 12-bits
        Signal to noise ratio   > 100
        Square wave response    > 40
 
      The instrument is from Space Applications Centre, Ahmedabad, India.
 
    M3
    --
      The Moon Mineralogy Mapper (M3) is an imaging spectrometer that operates
      from the visible into the near-infrared (0.42 to 3.0 micron) where
      highly diagnostic mineral absorption bands occur.  The instrument
      parameters and measurement modes for M3 are:
 
        Overall:
           40-km FOV (allows contiguous orbit overlap)
           405 to 3000 nm spectral range
           12 bits/pixel
        Target mode (full resolution):
           6000 spatial pixels (70 m/pixel)
           260 spectral channels (10 nm/channel)
           1 GB/orbit downlink:  10 to 12 deg longitude swath
        Global Mode (reduced resolution):
           300 spatial pixels (140 m/pixel for 100-km lunar polar orbit)
           86 spectral channels (mixed 20 and 40 nm/channel)
           1 GB/orbit downlink:  135 deg longitude swath (alternating poles)
 
      The instrument is from Jet Propulsion Laboratory, NASA, USA.
 
    LLRI
    ----
      The Lunar Laser Ranging Instrument (LLRI) is designed to measure the
      topography of the lunar surface.  A 10-mJ diode-pumped pulsed laser
      together with a 20-mm diameter telescope and a silicon avalanche
      photodiode are the principal optical assemblies of this active remote
      sensing instrument.  The specifications of LLRI are:
 
        Maximum range          : 100 km (>100 km)
        Range accuracy         <= 5 m (<5 m)
        Range resolution       <= 5 m (<1.5 m coarse, <25 cm fine)
        Data update rate       : 10 Hz
        Transmitter wavelength : 1064 nm
        Pulse energy (min)     : 10 mJ
        Spectral bandwidth     : 0.05 nm
        Spectral Rx bandwidth  < 10 nm
        Optical Rx FOV         : 0.05 deg
 
      The instrument is from Laboratory for Electro-optics, Bangalore, India.
 
    C1XS
    ----
      The Chandrayaan-1 X-ray Spectrometer (C1XS) is an X-ray imaging
      spectrometer comprising 24 Swept Charge Device (SCD) detectors and a
      micro-structure collimator/filter assembly.  The detectors are arranged
      in three arrays of 8 (2 x 4) detectors each, providing an overall field
      of view of 32 by 12 degrees in the 0.5 to 10 keV range with a resolution
      of 140 eV.  The SCDs are based upon CCD technology but have
      significantly lower read noise and can also operate at higher
      temperatures.  (The C1XS SCDs operate with good signal-to-noise at -10
      degrees Celsius.)  This is achieved by an electrode and clocking
      arrangement that 'sweeps' the charge to one collector in a corner of the
      chip.  The instrument is from Rutherford Appleton Laboratory, UK.
 
    XSM
    ---
      An X-ray Solar Monitor (XSM) supports the C1XS observations, providing
      solar spectra as calibrations for the lunar data collected by C1XS from
      which absolute elemental abundances can then be derived.  XSM has a wide
      field of view of 104 degrees and operates in the 0.8 to 20 keV spectral
      range. Stand-alone observations of long-term solar X-ray emissions can
      also be made.  The detector comprises silicon diodes cooled by Peltier
      elements. The instrument is from Rutherford Appleton Laboratory, UK.
 
    SIR-2
    -----
      The Sub Infrared Spectrometer (SIR-2) is a miniaturized point-
      spectrometer with a InGaAs array detector designed to provide good
      signal-to-noise at temperatures around -70 degrees Celsius.  The
      spectrometer operates in the 0.9- to 2.4-micrometer wavelength range and
      has 256 spectral channels with a resolution per channel of 6 nm/pixel.
      This is coupled to a lightweight off-axis telescope which has an
      aperture of 70 mm and a field of view of 1.1 mrad.  A dedicated radiator
      provides passive cooling of the optics and the spectrometer during
      observations.  The instrument is from Max Planck Institute for Solar
      system science, Germany.
 
    HEX
    ---
      High Energy X-ray spectrometer (HEX) is designed to have a spatial
      resolution of about 33 km at energies below 120 keV.  The low signal
      strength of these emissions requires a large area detector with high
      sensitivity and energy resolution, thus a new generation CdZnTe solid
      state detector is used in this experiment.  The specifications of HEX
      are:
 
        Energy range        : 30 to 270 keV
        Energy resolution   : 12% at 60 keV
        ACS threshold       ~ 50 keV
        Spatial threshold   : 33 km x 33 km FOV
 
      The instrument is from ISRO satellite centre, Bangalore, and Physical
      Research Laboratory, Ahmedabad, India.
 
 
        Instrument    : SARA (Sub-keV Atom Reflecting Analyzer)
        Type          : Mass spectrometer and solar wind monitor
        Measurements  : 10 ev - 2 kev with a 100-m spatial resolution
        Science Goals : Atmospheric neutrals (H-Fe) composition and magnetic
                        anomalies
        Principal Investigator : S. Barabash, ESA
 
    SARA
    ----
      The Sub-keV Atom Reflecting Analyser (SARA) comprises two detectors.
      The Chandrayaan Energetic Neutrals Analyser (CENA) is a low-energy
      neutral atom sensor with an range from 10 eV to 3.3 keV, and the Solar
      Wind Monitor (SWIM) is an ion mass spectrometer with an energy range
      from 10 eV to 15 eV.  The main characteristics of the two sensors are:
 
        Parameter              CENA                   SWIM
        ---------------------------------------------------------------------
        Particle to measure    Neutrals               Ions
        Energy range           10 eV to 3.2 keV       10 eV to 15k eV
        Energy resolution      50%                    7%
        Mass range             1 to 56 amu            1 to 40 amu
        Mass resolution        H,O, Na/Mg/Si/Al,      H,  He, O (> 20 amu)
                               K/Ca, Fe
        Full FOV               15 x 160 deg           9 x 180 deg
        Angular resolution     9 x 25 deg             4.5 x 22.5 deg
        G-factor/sector, w/o   10^-2 cm2^2 sr eV/eV   1.6x10^-4 cm^2 sr eV/eV
        Efficiency             0.2 cm^2 se eV/eV(at 25eV)
        Efficiency (%)         0.01 to 1              0.1 to 5
 
      The instrument is from Swedish Institute of Space Physics, Sweden, and
      Space Physics Laboratory, VSSC, Trivandrum, India.
 
    Mini-SAR
    --------
      The Miniaturized Synthetic Aperture Radar (Mini-SAR) is a single
      frequency (S-band; 13-cm wavelength) synthetic aperture radar in a light
      weight (9 kg) package.  Mini-SAR utilizes a unique hybrid polarization
      architecture which allows determination of the Stokes parameters of the
      reflected signal, intended to distinguish volume scattering (caused by
      presence of ice) from other scattering mechanisms.  The parameters for
      Mini-SAR are:
 
        Frequency            : 2.38 GHz
        Spacecraft velocity  : 1631 m/s
        Range swath          : 8 km
        Strip length         : 325 km (SAR), 300 km (Scatterometer)
        Boresight fain       : 26.1 dB
        Antenna efficiency   : 53%
        Transmit pulse width : 84 micro-sec (SAR), 83 micro-sec
                               (Scatterometer)
        PRF                  : 3100 Hz (SAR), 3750 Hz (Scatterometer)
        A/D sampling frequency : 8
 
      The instrument is from Applied Physics Laboratory, Johns Hopkins
      University, USA.
 
    MIP
    ---
      The Moon Impact Probe (MIP) has two technological and one scientific
      experiments:  a Moon Imaging System (MIS), a radar altimeter, and a mass
      spectrometer known as CHACE (Chandra's Altitudinal Composition
      Explorer). The nearly 34-kg MIP with features of a mini spacecraft is
      designed to be piggy-backed on main orbiter and released for descent to
      the Moon at a pre-determined location.  The MIS essentially comprises a
      CCD camera and processing electronics and is designed to acquire images
      of lunar surface, compress them, and then transmit the compressed data
      through a telemetry link to the orbiting Chandrayaan-1 spacecraft.  A
      altimeter consists of a C-band radar that makes use of an FM-CW type
      transmitter with central and modulation frequencies of 4.3 GHz and 100
      Hz, respectively, and a transmitted output power of 1 W (CW) with a
      frequency deviation of +/-50 MHz.  The salient features of CHACE are:
 
        Mass range     : 1 to 100 amu
        Detector type  : Electron multiplier
        Resolution     : Unit resolution
        Dynamic range  : 10^10
        Min. detectable partial pressure: 5 x 10^-14 torr
        Scan rate      : 15 spectra/minute
        Sensitivity    : 10^-1 A/torr
 
      The instrument is from Vikram Sarabhai Space Centre, Trivandrum, India.
 
    RADOM
    -----
      The Radiation Dose Monitor (RADOM) is designed to measure the spectrum
      (in 256 channels) of the energy deposited by primary and secondary
      cosmic particles.  It is a miniature spectrometer dosimeter containing a
      single 0.3-mm thick semiconductor detector with a 2-cm-square area, one
      low noise hybrid charge-sensitive preamplifier (A225F type) from AMPTEX
      Inc., a fast 12-channel analog-to-digital converter, two micro-
      controllers, and buffer memory.  A pulse analysis technique is used for
      obtaining the spectrum of the energy deposited in the silicon detector
      which is then analysed and further converted to deposited dose and flux
      values.  The instrument is from Solar-Terrestrial Influences Laboratory,
      Bulgarian Academy of Sciences.
 
 
  Mission Phases
  ==============
    Two main phases of significant periods of spacecraft activity are defined
    for the Chandrayaan-1 mission:  The Launch and Early Orbit phase and the
    Lunar Orbit phase.
 
    LAUNCH AND EARLY ORBIT
    ----------------------
      Mission Phase Start Date:  2008-10-22
      Mission Phase Stop Date:   2008-11-08
        The Launch and Early Orbit Phase extended from the launch of the
        spacecraft from the SDSC in Sriharikota, India, at 00:51 UT on 22
        October 2008.  This phase starts from lift-off and ends with lunar
        capture.  Orbit raising maneuvers and transmitting X-band data through
        the stowed DGA are the major activities during this phase.  During
        other major activities, the spacecraft was kept at single inertial
        attitude due to power, thermal, and communication link constraints.
        The RADOM instrument was turned on during the first transfer orbit and
        was kept on continuously.  Three images were taken by TMC during en
        route:  the Australian sector of Earth at 02:38 UT on 29 October 2008,
        the crescent Earth at 07:29 UT on 29 October 2008, after burn #4, and
        the crescent Moon at 08:25 UT on 4 November 2008, after burn #5.
 
    LUNAR ORBIT
    -----------
      Mission Phase Start Date:  2008-11-08
      Mission Phase Stop Date:   2009-08-28
 
      The sphere of influence occurred around 18:05:30 on 7 November 2008.
      The Lunar Orbit Insertion maneuver was carried out at 11:20:46 on 8
      November 2008 to put the spacecraft into an elliptical orbit (500 x 7500
      km) around Moon.  The orbit was later circularized to 100 x 100 km after
      four lunar burns.
 
      All the payloads were commissioned in a phased manner.  The
      commissioning
      dates of each payload were:
 
        .-----------------------------------.
        |              |   Commissioning    |
        |   Payload    |     Date (UTC)     |
        .-----------------------------------.
        |  TMC, RADOM  |  Operated en route |
        |  LLRI        |  2008-11-16T03:50  |
        |  HySI        |  2008-11-16T07:40  |
        |  Mini-SAR    |  2008-11-17T14:00  |
        |  M3          |  2008-11-18T22:15  |
        |  SIR-2       |  2008-11-19T08:23  |
        |  C1XS        |  2008-11-20T17:42  |
        |  HEX         |  2008-12-05T11:52  |
        |  SARA        |  2008-12-09T11:50  |
        |              |  2009-01-29T04:00  |
        .-----------------------------------.
 
 
    Summary of Sub-Phases during Lunar Orbit
    ========================================
 
      ****************************************************
      Name:  Limited operation zone (noon-midnight zone-1)
      ****************************************************
      START_DATE:  2008-11-16
      STOP_DATE:   2009-01-30
      Sun angle with respect to the orbital plane:  -30 deg to 45 deg.
      Scientific Focus:  Optical Imaging
      Instruments operated:  TMC, HySI, M3, SIR-2, C1XS, LLRI, RADOM
 
      DESCRIPTION:  To contain the bulk temperature of the spacecraft, the
      payload operations were restricted during this phase.  The maximum
      number of payload sessions in a day was four.  Typical data were
      collected of the surface of the Moon such as polar, equatorial (near
      side, far side), and higher latitude regions (near side, far side) by
      TMC, HySI, M3, SIR-2, C1XS, and LLRI.  A campaign to image Apollo
      landing sites by all the imaging payloads was carried out from 7 to 11
      January 2009.  A 180-deg yaw rotation of the spacecraft was carried out
      on 18 December 2008.
 
      ***************************************
      Name:  Intense imaging operation zone-1
      ***************************************
      START_DATE:  2009-01-31
      STOP_DATE:   2009-02-14
      Sun angle with respect to the orbital plane:  Greater than 45 deg and
      less than 60 deg.
      Scientific Focus:  Optical Imaging
      Instruments operated:  TMC, HySI, M3, SIR-2, C1XS, LLRI, RADOM, SARA
 
      DESCRIPTION:  During this period, all the optical imaging payloads were
      operated every orbit.  The coverage of TMC-HySI was around the
      equatorial region (+30 to -30 degrees), and M3 was operated in global
      mode.  SIR-2 and C1XS were operated during the illuminated limb of the
      orbit, including the terminator crossing, while LLRI was operated during
      the non-illuminated limb of the orbit.
 
      ***********************
      Name:  Dawn-dusk zone-1
      ***********************
      START_DATE:  2009-02-15
      STOP_DATE:   2009-04-15
      Sun angle with respect to the orbital plane:  Greater than 60 deg.
      Scientific Focus:  Radar imaging
      Instruments operated:  Mini-SAR, HEX, C1XS, RADOM, SARA
 
      DESCRIPTION:  During this period, Mini-SAR was operated at both poles.
      As the spacecraft bulk temperature was low, the power requirement for
      the heater increased.  HEX was operated during the poles for a period of
      20 minutes.  The spacecraft was re-oriented about 40 to 50 degrees about
      the yaw axis to maximize power generation and to charge the battery
      during the payload non-operation period.  The solar array was flipped by
      180 degrees on 25 March 2009 when the Sun angle was 60 degrees with
      respect to the solar panel.
 
      ***************************************
      Name:  Intense imaging operation zone-2
      ***************************************
      START_DATE:  2009-04-15
      STOP_DATE:   2009-05-18
      Sun angle with respect to the orbital plane:  Greater than 45 deg and
      less than 60 deg.
      Scientific Focus:  Optical imaging
      Instruments operated:  TMC, HySI, M3, SIR-2, C1XS, RADOM, SARA
 
      DESCRIPTION:  During this period, the regions that M3 did not image
      during the previous imaging season were covered in global mode.  Higher
      latitudes of the southern hemisphere (-30 to -60 degrees) were imaged by
      TMC-HySI. SIR-2 and C1XS were operated during the illuminated limb of
      the orbit. However, after failure of a star sensor, all payload
      operations were minimized.
 
      *****************************************************
      Name:  200-km operation zone-1 (noon-midnight zone-2)
      *****************************************************
      START_DATE:  2009-05-19
      STOP_DATE:   2009-08-16
      Sun angle with respect to the orbital plane:  Less than 60 deg.
      Scientific Focus:  Optical imaging
      Instruments operated:  TMC, HySI, M3, SIR-2, C1XS, RADOM, SARA
 
      DESCRIPTION:  The altitude of the orbit was raised to 200 km during the
      period from 16 to 19 May 2009.  During this maneuver, all the
      illumination-dependent instruments were operated.  Systematic coverage
      was performed by TMC-HySI starting with the polar zone, mid-latitude
      regions, and global coverage was carried out by M3 under different
      illumination conditions.  A 180-degree yaw rotation was carried out on
      18 June 2009. Periodic attitude acquisition maneuvers were carried out.
      During the total solar eclipse on 22 July 2009, nine consecutive images
      of Earth were acquired by TMC to cover the path of totality.  Other
      payloads such as M3, SWIM (SARA), C1XS were also switched on during the
      eclipse.
 
      *************************************************
      Name:  200-km operation zone-2 (Dawn-dusk zone-2)
      *************************************************
      START_DATE:  2009-08-17
      STOP_DATE:   2009-08-28
      Sun angle with respect to the orbital plane:  Greater than 60 deg.
      Scientific Focus:  Radar imaging
      Instruments operated:  Mini-SAR, C1XS, RADOM
 
      DESCRIPTION:  Due to the change in the altitude of the orbit, the Mini-
      SAR operation sequences were modified and polar imaging in SAR mode was
      started on 17 August 2009.  Periodic attitude acquisition maneuvers were
      carried out.  On 20 August 2008, bi-static observation with the Lunar
      Reconnaissance Orbiter (LRO) was attempted.  However, it was not
      successful because of the uncertainty in the attitude.  The RADR imaging
      continued until radio contact with the spacecraft was lost on 28 August
      2009.