By 
March 4th, 2022
AGI, an Ansys company, reconstructed the stage impact circumstances using specialized software.
Credit: AGI
That out-of-control rocket stage has smacked into the Moon’s far side, given early predictions of its scheduled demise. The discarded hardware has been identified as a wayward Chinese Long March 3C rocket stage from the Chang’e 5-T1 mission in 2014.
Tagging the out-of-control stage to China comes from Bill Gray, manager of Project Pluto that supplies astronomical software, both commercial and freeware, to amateur and professional astronomers.
“I am quite confident that it impacted,” Gray told Inside Outer Space. “We had lots and lots of tracking data for the object, and there is nothing acting on it except the forces of gravity and sunlight. The effects of gravity are almost perfectly accounted for.”
The sunlight effects might be off by a few kilometers, Gray said, but nowhere near enough to turn the impact into a miss.
“Unless the object was removed by an occult hand, it hit the Moon a few hours back,” Gray said.
Nominal trajectory
Just to be sure the stage did auger in, there will be a search for the object along its nominal trajectory with optical telescopes next week to make sure nothing is there, said Vishnu Reddy at the University of Arizona in Tucson.
Vishnu Reddy and his student researchers at the University of Arizona.
Credit: Mikayla Mace Kelley, University Communications/University of Arizona
Reddy and his student researchers have made early observations of the errant upper stage using the Rapid Astronomical Pointing Telescopes for Optical Reflectance Spectroscopy (RAPTORS) system, a telescope atop the Kuiper Space Sciences building on campus.
“Then we wait for the crater images from LRO,” Reddy told Inside Outer Space. NASA’s Lunar Reconnaissance Orbiter’s powerful camera system will scan the anticipated impact zone — in the vicinity of the large Hertzsprung Crater — to look for the crash site.
NASA’s Lunar Reconnaissance Orbiter (LRO).
Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab
Upshot
Additionally, onboard LRO instruments are on tap to scan for any upshot from the rocket stage impact.
“LRO won’t be close enough to the crash to observe it as it’s happening,” said David Paige, a planetary scientist at the University of California, Los Angeles. LRO’s Lyman Alpha Mapping Project (LAMP) sensor will attempt to point at the limb to observe the impact plume, he said.
“Eventually, we will hopefully find the crash site. However, the targeting of this is highly uncertain, so it might be like trying to find a needle in a haystack,” Paige said.
If found, then LRO’s Diviner Lunar Radiometer Experiment can observe it and hopefully detect evidence of the crash from orbit, Paige said, perhaps in a few months from now. Paige is the principal investigator for Diviner.
AGI, an Ansys company, reconstructed the stage impact circumstances using specialized software.
Credit: AGI
Approach and impact simulation
Meanwhile, a physics-based animation simulating the rocket’s approach and impact has been issued by Analytical Graphics, Inc. (AGI), headquartered in Exton, Pennsylvania.
A Systems Tool Kit (STK) and other fancy computer software was put to the task said Alex Lam of AGI. “Nearly seven years after launch and several harmless flybys of the Moon, the orbit became altered. A series of three flybys set up the booster for its eventual demise,” Lam said. These flybys occurred on September 18, 2021, January 5, 2022, and February 5, 2022.
The tumbling of the China’s booster resulted in a time-varying force caused by solar radiation pressure impinging on the spent hardware’s sunlit side and introduced new complexities for an accurate model of the forces on its body, Lam added.
Using STK’s Electro-Optical Infrared (EOIR) capability, AGI modeled the LRO’s wide angle camera with publicly available technical specifications and created a rendering of what it might see on its pass at the end of March.
Credit: AGI
“With this newly processed data, we found that the booster will impact the Moon at 4.58° N, 129.06° W on March 4, 2022, 12:26:58 UTC. This changes our impact time by about one minute and moves the impact site prediction by just over [155 miles] 250 kilometers, closer to the center of the Hertzsprung Crater,” Lam said.
With a little bit of luck
While the impact won’t be viewed in real time, satellites orbiting the Moon may see the aftermath.
India’s Chandrayaan-2’s Moon orbiter.
Credit: ISRO
In particular, NASA’s LRO and the Indian Space Research Organization’s Chandrayaan-2 may be able to pick out the new crater created by the booster’s impact, Lam added. “Both satellites have onboard cameras capable of imaging the predicted crash site, and if we’re lucky we might find it!”
“With these orbits, we expect that the LRO’s first post-impact pass over the sunlit Hertzsprung Crater will occur on March 28, 2022, and Chandrayaan-2’s first pass will come shortly after on April 4, 2022,” Lam said. “Pending instrument availability and a little bit of luck, we might be able to catch a glimpse of the booster’s remnants! Additionally, the impact crater is likely to expose some fresh lunar crust for imaging by these satellites, and the resulting data may have scientific value for geologists researching the Moon.”
To view the informative AGI video – “Alternate View of Chang’e 5-T1 Booster Impact” – go to:
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