That Mysterious Space Debris Is Likely Part of a Long-Dead NASA Moon Probe

Thursday, 14 January 2016 - 1:15PM
Space
Astronomy
Thursday, 14 January 2016 - 1:15PM
That Mysterious Space Debris Is Likely Part of a Long-Dead NASA Moon Probe
In November 2015, a mysterious piece of space debris, nicknamed WT1190F, was spotted hurtling towards Earth. Astronomers quickly determined that it wouldn't cause any major problems on the ground; most of it would burn up upon entry into the atmosphere, and the rest would fall harmlessly into the Indian Ocean. However, a few missing pieces of information still left them baffled - they had no idea what the object is, where it came from, or why it was only just showing up on their radars.

As predicted, a 1-meter piece of the debris landed in the Indian Ocean, and scientists immediately began working to trace the trajectory and composition of the debris back to its origin. Now, according to a new report in Nature, researchers have identified the falling debris as part of the rocket of the Lunar Prospector, a 1998 NASA moon probe. 

Launched in January 1998, The Lunar Prospector was sent to map the moon's surface composition and look for possible deposits of polar ice, measure magnetic and gravity fields, and study lunar gases. Following its four-day journey to the moon, it entered lunar orbit and started sending data back to ground control on Earth. In March of that same year, scientists announced that the Lunar Prospector's neutron spectrometer had detected hydrogen at both lunar poles, which was later theorized to be in some form of water ice. The mission concluded in July 1999, after scientists deliberately aimed the Lunar Prospector to crash into a permanently shadowed area of the moon near the lunar South Pole. Researchers hoped that the impact would release water vapor from the hypothesized ice deposits, and that the plume would be detectable from Earth, but no such plume was observed. 

Now, researchers believe WT1190F is a broken-off piece from the Lunar Prospector's explosive impact, but caution that this is only the "leading candidate" in a series of theories about WT1190F's origins. However, this hypothesis does come with a fair bit of scientific calculations to back itself up. Telescopes had occasionally picked up WT1190F's orbit as early as 2009, but until this past November, no one realized that it was going to strike Earth. By going back and combining the information taken from each sighting, researchers reconstructed WT1190D's trajectory around the Earth, and beyond the Moon's orbit. From this, they were able to determine that the path resembled a journey to the moon. 

Even with this crucial piece of the puzzle in place, there are still dozens of moon missions to sift through. However, researchers believe that they can eliminate many of them based on the timeline of the collision. Any object traveling on WT1190F's course for much longer than a decade would have already hit Earth or swerved into solar orbit, explains astronomy-software developer Bill Gray, so that rules out an Apollo mission or one of the other early Moon shots. 

Harvard Astrophysicist Jonathan McDowell adds that many of the rock segments used in more recent missions can also be ruled out because they end up in orbit around the Sun, rather than the Earth. Still others are ruled out because, when observed in orbit, they are unable to match WT1190F's spin rate of 40 revolutions per minute.

The fragment itself was analyzed, and signals of titanium oxide and hydrogen were found. Based on this, Peter Jenniskens of SETI speculates that the object could have been a titanium-walled vessel containing residual fuel. This matches with the Lunar Prospector's translunar injection module, which had a titanium case, but not with similar modules on Japan's Nozomi Mars probe, which had carbon fibre cases. 

As astronomers continue to search the archives for more sightings of WT1190F that predate 2009, they remain hopeful that more support for the Lunar Prospector theory can be found. If the debris' orbit can be traced back further in time, it can be compared to the path of the Lunar Prospector to see how well they match. Though the chance of finding any earlier sightings is pretty slim, the research team remains hopeful that more and more evidence will soon be unearthed to support their hypothesis.
Science
NASA
Space
Astronomy

Load Comments