The objectives of the Lyman-Alpha Mapping Project (LAMP) investigation are to:

  •  Search for exposed water ice near the lunar poles and in PSRs using reflected Lyman-Alpha (α) sky-glow and far-ultraviolet starlight.
  • Obtain landform maps in the PSR regions and serve as a pathfinder for a lunar natural light night vision system.
  •  Obtain data on the tenuous lunar atmosphere. 

The LAMP instrument (shown in Fig. 1) is a near-clone of the sensitive (∼1 Rayleigh level), lightweight (∼4 kg), low-power (∼4 W) ALICE imaging UltraViolet Spectrometer.

The presence of an excess hydrogen (H) signature, as detected by neutron spectroscopy, cannot guarantee the hydrogen is in the form of water without other supporting measurements. LAMP provides the unique capability of being able to spectrally fingerprint exposed H2O frost in the lunar polar regions. This will be accomplished using observations illuminated purely by Lyman-α sky-glow and broadband far ultra-violet (FUV) starlight. The lifetime of exposed water frost in polar cold traps is predicted to be short, owing to regolith gardening and sputtering processes. However, even if this is true, thin surface
deposits of recently deposited frost must exist in an equilibrium set by the balance between source and loss rates to the pole; their discovery would be a major find for LRO. Water ice has a diagnostic spectral reflectance signature at 120–180 nm, as evidenced by ultraviolet spectra obtained in the laboratory as well as on icy surfaces in the solar system. Owing to this signature, FUV spectroscopy provides a way to directly fingerprint H2O-frost exposed on the lunar surface, even at the relatively small (∼4%) mixing ratios predicted by volatile transport models and the 1.5% level. To make these detections LAMP will obtain spectral maps across the lunar surface, and retrieve H2O frost abundances (or strong upper limits) by rationing PSR spectra to those of waterless (“dry”) regions away from the PSRs.

Fig 1 LAMP design as seen from above (left) and below (right)

LAMP is comprised of a telescope and Rowland-circle spectrograph. LAMP has a single 40×40 mm2 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 a double-delay line (DDL) microchannel plate (MCP) detector. The 2-D (1024×32)-pixel format detector is coated by a CsI solar-blind photocathode and has a cylindrically-curved MCP-stack that matches the Rowland-circle. LAMP is controlled by an Intel 8052 compatible microcontroller, and utilizes lightweight, compact, surface mount
electronics to support the science detector, as well as the instrument support and interface electronics.The LAMP instrument support electronics are largely single-string, but include redundant features in certain high-value areas (e.g., the power supplies). The LAMP electronics include two low-voltage power supplies, actuator electronics, the Command & Data Handling (C&DH) electronics, the optics decontamination heater system, and two detector highvoltage power supplies. All of these elements 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[8].