Shadow-Piercing NASA Camera Rides To Moon Aboard Korean Craft
NASA plans to send a new, light-sensitive camera to explore the moon’s most shadowed regions.
The device, a revamping of the instrument that has circled the moon on the Lunar Reconnaissance Orbiter (LRO) since 2009, will hitch a ride aboard South Korea’s first lunar exploration mission, the Korea Pathfinder Lunar Orbiter (KPLO).
The Korea Aerospace Research Institute provided NASA 15 kilograms (33 pounds) of payload space aboard its orbiter. Following a solicitation, the space agency selected ShadowCam.
ShadowCam was proposed by Arizona State University planetary geologist Mark Robinson, who also built the LRO Camera (LROC), and his team. Malin Space Science Systems, which built the LROC, will also build ShadowCam.
ShadowCam will look for evidence of water ice in the permanently shadowed regions of the moon.
Water is an example of a class of substances called volatiles, which have low boiling points and therefore tend not to stick around unless they are preserved or created anew by some process.
“I’m really glad that we’re given this opportunity on the Korean orbiter to follow up on some of the discoveries we made with LRO," Robinson said. "Despite the fact LRO had multiple instruments looking at the poles, we still don’t understand the distribution of volatiles.”
The landmark Pink Floyd album notwithstanding, there really isn’t a “dark side of the moon.” But lunar areas that never receive sunlight – frigid craters and mountain shadows – could conceal a treasure trove of water ice, especially near the poles.
Using solar power, astronauts or colonists could break lunar water into hydrogen and oxygen for rocket fuel or fuel cells. They could also just drink it.
The LRO packed water-sniffing gear, but its LROC camera could not properly pierce deep shadows. That’s because the LRO’s equipment reflected its main mission: To help NASA spot landing zones for future astronauts and determine how to build a Moon base that could serve as a stepping stone to more ambitious missions.
Before the Lunar Reconnaissance Orbiter produced its 3-D map, NASA had better maps of Mars than of Earth’s own natural satellite.
“We were collecting the data that was needed. And it was rather limited, based on the capabilities of the spacecraft," Robinson said. "But they needed specific engineering data to help select future landing sites and – for engineering purposes, in terms of designing the lunar lander and other pieces of hardware, in our return to the moon.”
Previous missions hinted at the possible presence of moon ice. In the mid-1990s, the Clementine spacecraft detected bright radar reflections that might have been caused by ice in the moon’s south pole craters. In 1998, NASA’s Lunar Prospector detected hydrogen that might, or might not, have come from water molecules.
LROC improved on its predecessors, and ShadowCam will ratchet LROC’s photon-gathering ability up further. With the new camera, which captures larger pixels with longer exposures at a higher orbit, the instrument’s light sensitivity is 800 times LROC’s – the better to peer into those frigid polar craters.
“If you’re in a hole near the pole, that’s where the sun never shines. And so, it gets very, very cold in there, something on the order – the coldest areas are about 25 degrees Kelvin [-414.67 degrees Fahrenheit]. I think warmer permanently shadowed areas are 40-70 degrees Kelvin [-387.67 degrees Fahrenheit to -333.67]. And that’s crazy cold,” Robinson said.
Because the moon’s axis only tilts about 1.5 degrees, the satellite barely has seasons at all, and the polar regions receive roughly the same amount of sun year round.
Robinson explained that, if a water source, such as a comet, strikes the moon, some portion of the rocky ice ball will vaporize, but some of its icy remains will end up in one of these permanently shadowed craters, which will preserve them in a dark deep freeze.
“Once it’s in there, there’s hardly any energy, so they just sit there, and they can’t escape," he said. "And the idea is, over geologic time, those volatiles can build up.”
ShadowCam will complete LRO’s mapping work, seek ice signs – such as reflectivity changes and geological hints of permafrost processes – and set the stage for future surface missions.
“To really nail this, were going to have to put a lander or rover down in these craters. But what we’re going to be able to do with ShadowCam is really map out exactly where to go to get the answer,” Robinson said.
No firm launch date has been set.