Ten years ago today (Oct. 9), NASA slammed a hunk of space junk into the moon, forever changing our perception of Earth's nearest neighbor.
The space agency's Lunar Crater Observation and Sensing Satellite (LCROSS) and Lunar Reconnaissance Orbiter (LRO) missions launched together on June 18, 2009, riding atop a United Launch Alliance Atlas V rocket.
LRO sped to lunar orbit, where it continues to operate today. But LCROSS remained attached to the Atlas V's Centaur upper stage and went into a long, elliptical path around Earth that put it on an intentional collision course with the moon.
The goal was to slam into a permanently shadowed polar crater, to see if there was water ice down in those frigid depths — and, if so, how much. India's Chandrayaan-1 mission had recently spotted evidence of water across much of the lunar surface, and LCROSS aimed to assess the moon's stores of this precious resource in greater depth.
The Centaur barreled into Cabeus Crater, near the lunar south pole, early in the morning of Oct. 9, 2009, blasting large amounts of debris high above the moon's surface. The LCROSS spacecraft flew through this ejecta plume, studying its composition in detail. LCROSS relayed its measurements back to the mission team and then hit Cabeus as well, 6 minutes after the Centaur did.
The results of this suicide mission were exciting for anyone who wants humanity to explore and settle the moon. LCROSS found that Cabeus' floor is 5.6% water ice by mass (plus or minus 2.9%). That's about twice as wet as Sahara Desert soil, mission team members have said.
"When the LCROSS results came out, the entire concept of the moon and its water inventory changed dramatically," LCROSS Principal Investigator Tony Colaprete, of NASA's Ames Research Center in Silicon Valley, said yesterday (Oct. 8) in a NASA Q&A. "This came on top of several other missions that saw suspected signs of water from orbit, and it was all enough for governments around the world to pivot and put their attention on the moon."
Indeed, NASA is targeting the south pole for a 2024 crewed landing, the first human mission to the lunar surface since Apollo 17 in 1972. The new work is part of the space agency's Artemis program, which aims to establish a long-term, sustainable presence on and around the moon by 2028.
Lessons learned from this ambitious lunar exploration campaign will enable NASA and its international partners to push even farther out, to the ultimate human-spaceflight destination: Mars.
The LCROSS results reverberated beyond the walls of government space agencies as well, Colaprete said.
"Also, it sparked a new commercial sector to form around extracting water on the moon," he said in the NASA Q&A. "The identification of water and other potential resources by LCROSS and other missions has motivated companies to develop services to the moon. NASA is helping that along by providing business to these fledgling commercial services."
For example, robotic landers built by the companies Astrobotic and Intuitive Machines will carry NASA science and technology gear, as well as payloads from other customers, to the lunar surface in 2021.
Other companies, such as Moon Express and ispace, are building lunar surface craft as well, to help access and exploit the moon's prodigious stores of water ice. In addition to keeping human explorers alive, this resource can be processed into rocket fuel, allowing spacecraft to fill their tanks on the go. Off-Earth propellant depots could be a huge breakthrough, allowing more ambitious missions down the road, NASA officials and exploration advocates have said.
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Mike Wall's book about the search for alien life, "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), is out now. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.