Seeing into the Shadows

What is ShadowCam?

ShadowCam is a focused investigation of the Moon’s permanently shadowed regions (PSRs) that will provide critical information about the distribution and accessibility of volatiles in PSRs at spatial scales required to both mitigate risks and maximize the results of future exploration activities. ShadowCam is a high-heritage instrument based on the successful Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) and will be over 100× more sensitive (altitude dependent) than the current NAC.

ShadowCam will address three of the four strategic knowledge gaps (SKGs) through high-resolution, high signal-to-noise ratio imaging of PSRs illuminated only by reflected light, without duplicating measurements from KARI instruments (ShadowCam will saturate while imaging illuminated ground, with no harmful consequences to the shadowed portion of the image).

Science Objectives

  • Map albedo patterns in PSRs and interpret their nature:
    ShadowCam will search for frost, ice, and lag deposits by mapping reflectance with resolution and S/N comparable to NAC images of illuminated terrain.

  • Investigate the origin of anomalous radar signatures associated with some polar craters:
    ShadowCam will determine whether high-purity ice or rocky deposits are present inside PSRs.

  • Document and interpret temporal changes of PSR albedo units:
    ShadowCam will search for seasonal changes in volatile abundance in PSRs by acquiring monthly observations.

  • Provide hazard and trafficability information within PSRs for future landed elements:
    ShadowCam will provide optimal terrain information necessary for polar exploration.

  • Map the morphology of PSRs to search for and characterize landforms that may be indicative of permafrost-like processes:
    ShadowCam will provide unprecedented images of PSR geomorphology at scales that enable detailed comparisons with terrain anywhere on the Moon.

Camera Characteristics

Camera Design Time Delay Integration pushbroom
FOV (cross track) 2.86°
Image Scale 1.7 m/pix
Signal-to-Noise Ratio >100
Pixel Size 12 μm
Instantaneous FOV 17.1 μrad
Image Size (sensing pixels) ~3000 (cross-track)
Image Footprint Max 5 km × ~140 km
Optics f/3.6 Cassegrain (Richey-Chretien)
Focal length 700 mm
Primary Mirror Diameter 195 mm
MTF (Nyquist) 0.2
Aperture 194.4 mm
TDI lines 32
Sensitivity ~200× better than NAC
Mass 7.2 kg
Volume 118 × 27 cm (w/ radiator)
Peak Power 9.3 W
Average Power 6.4 W
Image of the ShadowCam instrument in the cleanroom at MSSS in San Diego.
The rings inside the baffle (left side) were especially designed to reduce stray light from degrading pictures of PSRs. The orange material is a thermal blanket that protects the telescope from the harsh space environment.
Image of the ShadowCam instrument, focusing on the details of the electronics and radiator components.
Close up view of the focal plane electronics and radiator (checkered mirror) that will keep the detector cool while in lunar orbit.
Technical drawing of the ShadowCam instrument with the sunshade, telescope, adapter plate, electronics box, and radiator labeled.
ShadowCam technical drawing with labeled components.

Science and Operations Team

ShadowCam leverages key personnel from LROC to build, operate, and analyze observations.
Name Position Affiliation
Mark S. Robinson Principal Investigator Arizona State University
Prasun Mahanti Deputy Principal Investigator Arizona State University
Ben Bussey Co-Investigator Applied Physics Lab
Lynn Carter Co-Investigator University of Arizona
Brett Denevi Co-Investigator Applied Physics Lab
Nicholas Estes Co-Investigator Arizona State University
Dave Humm Co-Investigator SPICACON
Erwan Mazarico Co-Investigator Goddard Space Flight Center
Michael Ravine Co-Investigator Malin Space Science Systems
Emerson Speyerer Co-Investigator Arizona State University
Robert Wagner Co-Investigator Arizona State University