urn:nasa:pds:context:instrument:lro.lamp 1.0 1.11.0.0 Product_Context urn:nasa:pds:context:instrument:lamp.lro 2021-02-24 1.0 Changed inst LIDs from u:n:p:c:i:instID.scID to u:n:p:c:i:scID.instID And per "Guide toPDS4 Context Products" v1.7, changed all lidvid_reference to lid_reference urn:nasa:pds:context:instrument_host:spacecraft.lro instrument_to_instrument_host Gladstone, G.R., S.A. Stern, K.D. Retherford, R. Black, J.R. Scherrer, D.C. Slater, J.M. Stone, P.D. Feldman, and D. Crider, LAMP: the Lyman Alpha Mapping Project aboard the NASA Lunar Reconnaissance Orbiter mission, Astrobiology and Planetary Missions, Hoover, R.B., G.V. Levin, A.Y. Rozanov, and G.R. Gladstone, Editors, Proceedings of SPIE, 5906, 380-388 (2005). reference.GLADSTONEETAL2005 Gladstone, G.R., S.A. Stern, K.D. Retherford, R.K. Black, D.C. Slater, M.W. Davis, M.H. Versteeg, K.B. Persson, J.Wm. Parker, D.E. Kaufmann, A.F. Egan, T.K. Greathouse, P.D. Feldman, D. Crider, W.R. Pryor, and A.R. Hendrix, LAMP: The Lyman Alpha Mapping Project on NASA's Lunar Reconnaissance Orbiter Mission, Space Sci. Rev., submitted (2008). reference.GLADSTONEETAL2008 Slater, D.C., S.A. Stern, T. Booker, J. Scherrer, M.F. A'Hearn, J.L. Bertaux, P.D. Feldman, M.C. Festou, and O.H.W. Siegmund, Radiometric and calibration performance results for the Rosetta UV imaging spectrometer ALICE, UV/EUV and Visible Space Instrumentation for Astronomy and Solar Physics, Oswald H.W. Siegmund, Silvano Fineschi, Mark A. Gummin, Editors, Proceedings of SPIE, vol. 4498, 239-247, 2001. reference.SLATERETAL2001 Slater, D.C., M. Davis, C.B. Olkin, S.A. Stern, and J. Scherrer, Radiometric performance results of the New Horizons' ALICE UV imaging spectrograph, SPIE Int. Soc. Opt. Eng., vol. 5906, 2005. reference.SLATERETAL2005 Stern, S.A., D.C. Slater, W. Gibson, J.R. Scherrer, M.F. A'Hearn, J.-L. Bertaux, P.D. Feldman, and M.C. Festou, Alice-an ultraviolet imaging spectrometer for the Rosetta Orbiter, Adv. Space Res., 21, 1517-1525 (1998). reference.STERNETAL1998 Stern, S.A., J. Scherrer, D.C. Slater, G.R. Gladstone, L.A. Young, G. Dirks, J. Stone, M. Davis, and O.H.W. Siegmund, ALICE: The ultraviolet imaging spectrograph aboard the New Horizons spacecraft, X-Ray, UV, Visible, and IR Instrumentation for Planetary Missions, Oswald H.W. Siegmund and G. Randall Gladstone, Editors, Proceedings of SPIE, vol. 5906B, 2005. reference.STERNETAL2005 Stern, S.A., D.C. Slater, J. Scherrer, J. Stone, G. Dirks, M. Versteeg, M. Davis, G.R. Gladstone, J.W. Parker, L.A. Young, and O.H.W. Siegmund, ALICE: The Ultraviolet Imaging Spectrograph aboard the New Horizons Pluto-Kuiper Belt Mission, Space Sci. Rev., Volume 140, Numbers 1-4, pp. 155-187, 2008. reference.STERNETAL2008 LYMAN ALPHA MAPPING PROJECT Spectrograph not applicable not applicable INSTRUMENT OVERVIEW =================== The LAMP description is adapted from Gladstone et al. (2005) [GLADSTONEETAL2005] and Gladstone et al. (2008) [GLADSTONEETAL2008]. The Lyman Alpha Mapping Project (LAMP) instrument is one of the remote sensing instruments on the Lunar Reconnaissance Orbiter (LRO) spacecraft that will acquire orbital observations of the lunar surface during a one year primary mapping phase. LRO is scheduled to launch in April 2009 and arrive at the Moon approximately four days later. Lunar orbit insertion will place the spacecraft into a quasi-frozen 30 x 216 kilometer near- polar orbit suitable for the commissioning phase, which will last approximately 60 days. At the end of commissioning, final orbit maneuvers will insert LRO into the nominal mission orbit, a mean 50 kilometer polar orbit in which LRO will remain for at least one year. LAMP is a far ultraviolet spectrograph provided by the Southwest Research Institute (SwRI). LAMP's nadir observing geometry on the LRO spacecraft will translate its 0.3 x 6 degree field of view into a footprint of 0.26 x 5.2 kilometers on the lunar surface from an altitude of 50 kilometers. LAMP will measure the signal reflected from the nightside lunar surface and Permanently Shaded Regions (PSRs) using Lyman-alpha sky-glow and UV starlight as light sources. LAMP data will nominally be taken entirely in time-tagged mode, allowing mapping at a variety of resolutions. Reflectance data will yield albedo maps of PSRs, spectra of PSRs will yield exposed water frost abundances, and atmospheric spectra will yield species abundances and variability. The LAMP instrument is closely based on the Pluto Alice (P-Alice) instrument design (Stern et al. 2005 [STERNETAL2005]; Slater et al. 2005 [SLATERETAL2005]; Stern et al. 2008 [STERNETAL2008]), which is, in turn, based largely on the Rosetta Alice (R-Alice) instrument design (Stern et al. 1998 [STERNETAL1998]; Slater et al. 2001 [SLATERETAL2001]), with only relatively minor changes in baffling, software, and the addition of a lunar terminator sensor. SPECIFICATIONS -------------- NAME: LAMP DESCRIPTION: Ultraviolet Mapping Spectrograph PRINCIPAL INVESTIGATOR: Randy Gladstone, SwRI WAVELENGTH RANGE: 57.5 - 196.5 nm (first order) [Note 1] FIELD OF VIEW: (0.31 +/- 0.01) X (6.00 +/- 0.01) deg [Note 1] ANGULAR RESOLUTION: 0.29 +/- 0.03 deg per spatial pixel [Note 1] WAVELENGTH RESOLUTION: 0.182 +/- 0.001 nm [Note 1] Note 1: Measured performance SCIENTIFIC OBJECTIVES ===================== The primary scientific objectives of LAMP are: 1) To generate albedo maps of all PSRs 2) To develop exposed water-frost concentration maps of the lunar polar regions CALIBRATION =========== Ground radiometric characterization and absolute calibration of the instrument was performed at SwRI's UV space instrument calibration facility located in SwRI's Space Science and Engineering Division. The radiometric vacuum chamber consists of a 4-inch diameter off-axis parabolic collimator mirror that is fed by a differentially pumped hollow- cathode UV light source and an Acton Research Corporation VM-502 vacuum monochromator. A variable slit and pinhole assembly at the output of the monochromator (and situated at the focus of the collimator mirror) allowed for point source illumination of the LAMP airglow input apertures. Radiometric characterization tests included the detector dark count rate, wavelength calibration, spectral and spatial point spread function (PSF) versus wavelength, filled slit spectral resolution, off-axis stray light attenuation, and absolute effective area measurements as a function of wavelength. See Gladstone et al. (2008) for further details. During the commissioning phase, the LAMP instrument will be commanded to perform five different calibration activities: (1) raster scan star calibrations; (2) stare star calibrations; (3) dark count rate calibrations; (4) flat field calibrations; and (5) stray light calibration. In addition to these calibration activities, LAMP will perform instrument characterizations such as high voltage (HV) discriminator setting tests as well as periodic decontamination using internal heaters. During the nominal mission phase, instrument calibrations will be performed in conjunction with the monthly station-keeping maneuvers. For LAMP these will include all five types mentioned above for the commissioning phase. OPERATIONAL CONSIDERATIONS ========================== The LAMP instrument will collect measurement data only over the night portion of the orbit until minimum mission objectives are satisfied. Nominally, LAMP will operate in pixel list (time-tagged photon) acquisition mode. When LRO crosses the lunar terminator (day to night), the high voltage (HV) will be ramped up to full operating level. The ramp-up is triggered by the Lunar Terminator Sensor (LTS). Prior to crossing the terminator again (night to day), the HV will be ramped down to a safe level by the LTS. While LAMP is operating over the night portion of the orbit, the instrument will generate measurement data at a rate of about 30 kbps. The spacecraft will collect and store the data on the flight recorder. The spacecraft will store about 113 minutes' worth (one orbit's worth) of measurement data in each data file. After minimum mission objectives have been completed, LAMP will operate over the full orbit. A small pin-hole in the aperture door of LAMP allows the instrument to operate over the entire orbit. The LAMP Science Operations Center (SOC) will generate any required command activity request. Activity requests are used to request special operations or update command sequences. During nominal operations, the LTS will be used to trigger the high-to-low and low-to-high voltage transitions. As a contingency, the Mission Operations Team (MOT) will have the ability to generate the daily command loads that include commands to trigger the voltage transitions based on the predicted terminator- crossing times generated by the Flight Dynamics Facility (FDF). This procedure will be used, if needed, as a backup to the LTS. LAMP operations also involve a number of constraints to avoid damage to the instrument. These include keeping the LAMP boresight pointed away from the Sun and other designated UV-bright stars, as well as making sure that the instrument is in a proper state prior to conducting certain operations. DETECTORS ========= The 2-D imaging photon-counting detector located in the spectrograph section of the instrument utilizes a microchannel plate (MCP) Z-stack that feeds the double-delay line (DDL) readout array. The input surface of the Z-stack is coated with an opaque photocathode of CsI. The detector body tube is a custom design made of a lightweight brazed alumina-Kovar structure that is welded to a housing that supports the DDL anode array. To capture the entire 57.5-196.5 nm passband and 6 degree spatial field of view (FOV), the size of the detector's active area is 35 mm (in the dispersion direction) by 20 mm (in the spatial dimension), with a pixel format of 1024 x 32 pixels. The 6 degree slit-height is imaged onto the central 22 of the detector's 32 spatial channels; the remaining spatial channels are used for dark count monitoring. LAMP's pixel format allows Nyquist sampling with a spectral resolution of 0.36 nm, and a spatial resolution of ~0.6 degree. The MCP Z-stack is composed of three 80:1 length-to-diameter MCPs that are cylindrically curved with a radius of curvature of 75 mm to match the Rowland-circle for optimum focus. The total Z-stack resistance is ~300 MOhms. The MCPs are rectangular in format (46 x 30 mm^2), with 12 um diameter pores. Above the MCP Z-stack is a repeller grid that is biased ~900 V more negative than the top of the MCP Z-stack. This repeller grid reflects electrons liberated in the interstitial regions of the MCP back down to the MCP input surface to enhance the detector quantum efficiency. The MCP Z-stack requires a high voltage bias of ~-3 kV; an additional -600 V is required between the MCP Z-stack output and the anode array (the anode array is referenced to ground). The lab-measured dark count rate of the flight MCP stack is quite low and stable--less than 6 Hz over the entire MCP active area. The on-orbit dark count rate will likely be considerably larger, however, (probably ~20 Hz or so) due to the energetic particle environment in space. ELECTRONICS =========== The detector electronics amplify and convert the detected output pulses from the MCP Z-stack to pixel address locations. Only those analog pulses output from the MCP that have amplitudes above a set threshold level are processed and converted to pixel address locations. For each detected and processed event, a 10-bit X (spectral) address and a 5-bit Y (spatial) address are generated by the detector electronics and sent to the LAMP command and data handling (C&DH) electronics for data storage and manipulation. In addition to the pixel address words, the detector electronics also digitizes the analog amplitude of the detected event output by the preamplifiers and sends this datum to the C&DH electronics. Histogramming of this 'pulse-height' information creates a pulse-height distribution used to monitor the health and status of the detector during operation. An analog count rate signal is output from the detector electronics to the C&DH to allow monitoring and recording of the detector total array count rate. This count rate is updated once per second and is included in the LAMP housekeeping data. A built-in 'stim-pulser' is included in the electronics that stimulates photon events at two pixel locations on the array. This pulser can be turned on and off by command and allows testing of the entire detector and C&DH electronics signal path without having to power on the detector high-voltage power supplies (HVPSs) or put light on the detector. The LAMP instrument support electronics include the low-voltage power supply (LVPS) and actuator electronics, the C&DH electronics, the optics decontamination heater system, and the redundant detector HVPSs. All of these subsystems are controlled by a radiation-hardened version of the Intel 8052 microprocessor with 32 kB of fuse programmable PROM, 128 kB of EEPROM, 32 kB of SRAM, and 128 kB of acquisition memory. The C&DH electronics are contained on four circuit boards located just behind the detector electronics. OPTICS ====== The LAMP spectrograph comprises a telescope and Rowland-circle spectrograph. LAMP has a single 40 x 40 mm^2 entrance aperture that feeds light to the telescope section of the instrument. Entering light is collected and focused by an f/3 off-axis paraboloidal (OAP) primary mirror at the back end of the telescope section onto the instrument's entrance slit. After passing through the entrance slit, the light falls onto a toroidal holographic diffraction grating, which disperses the light onto the DDL MCP detector. The OAP mirror and diffraction grating are constructed from monolithic pieces of aluminum, coated with electroless nickel and polished using low- scatter polishing techniques. The aluminum optics, in conjunction with the aluminum housing, form an athermal optical design. Both the OAP mirror and the grating are overcoated with sputtered Al/MgF2 for optimum reflectivity within LAMP's spectral passband. Besides using low-scatter optics, additional control of internal stray light is achieved using internal baffle vanes within both the telescope and spectrograph sections of the housing, a holographic diffraction grating that has low scatter and near-zero line ghost problems, and an internal housing with alodyned aluminum surfaces. In addition, the zero order baffle is treated with a nickel-phosphorus (Ni-P) black coating with very low surface reflectance at EUV/FUV wavelengths. OPERATIONAL MODES ================= LAMP has two detector data collection modes: i) pixel list mode; and ii) histogram mode. However, because of its nature and its mission, nearly all the LAMP data will be obtained in pixel list mode (exceptions will be made for flat-field and pulse-height distribution measurements). The science data from the detector are collected in the dual port acquisition memory that consists of two separate 32K x 16-bit memory channels. In pixel list mode each memory channel can hold up to 32K detector and/or time-hack events, where each detector event consists of a 16-bit word--an X-position word 10 bits in length, a Y-position word 5 bits in length, and a single status bit that distinguishes between a time-hack word and a detector event word. A time-hack word includes a single status bit plus 15 bits that encode the instrument time. When 32K detector address and time-hack events have accumulated in one of the two acquisition memories, that acquisition memory stops accumulating event data and begins to read the data out to a parallel-to-serial converter and a low-voltage differential signaling (LVDS) interface to the spacecraft on-board memory. At the same time that this LVDS readout is taking place, the other side of the dual acquisition memory continues to collect detector and time-hack data until it fills up, whereupon it reads out to the LVDS interface to the spacecraft memory, while the first acquisition memory takes over collecting detector and time-hack data. This back-and-forth data collection flow between both acquisition memories is called 'ping-pong' acquisition--it allows contiguous readout of detector event data as long as the event data rate does not exceed the rate at which the data can be read out of memory to the LVDS interface. The 'ping-pong' acquisition process is controlled using logic encoded in one of two floating-point gate arrays (FPGAs) within the C&DH electronics. LAMP also includes a flight software mechanism to filter out events from selected areas of the detector. This may be used to suppress 'hot' pixels that could develop in the detector, especially in the pixel list mode, which might otherwise consume a large fraction of the available acquisition memory. This filtering is performed before events are processed in either histogram or pixel list mode. The system defines up to 8 rectangular regions of 32 X 4 pixels that suppress any events from the selected regions from being processed. Configuration parameters allow for the placement of these filtered areas at any desired positions within the detector area. MEASURED PARAMETERS =================== See the discussion above regarding Operational Modes.