In November, we reported how the impact on the Moon from a Chinese Long March rocket booster had created an unusual double crater. For a booster that creates a double crater, some researchers believe that there is an additional, possibly secret payload in the forward end of the booster, as opposed to the rocket engines. But that may not be the case.
Other researchers feel that the extra mass is not secret, but possibly an inert structure such as a payload adapter added to the rocket to support the mission’s primary payload.
Chang’e 5-T1 is an experimental robotic spacecraft, launched on October 23, 2014, by the China National Space Administration (CNSA) to test a return capsule design planned for use in the future Chang’e 5 mission, the first ever sample-return effort. Change 5 landed on the Moon in November 2020 and successfully collected lunar samples from the Moon’s Ocean of Storms region, with the spacecraft landing back on Earth on December 16, 2020.
Before engaging in the first sample return effort for the country (and first in over forty years), China wanted to test the procedures and their sample return capsule. That was one of the 5 T-1 mission objectives.
The rocket is carrying a ‘Service Module’ satellite with a sample return capsule attached, said Phillip Stooke, professor emeritus at the University of Western Ontario, in an email to Universe Today. It requires an adequate support structure (called a payload adapter) to support the mass against vibration and facilitate launch.
Stooke explained how the Service Module flew around the Moon and back to Earth, where the capsule was released to test its ability to survive in the atmosphere again. The Service Module then returned to the Earth-Moon L2 point, remaining there for several months before entering a low lunar orbit, possibly to perform a gravity mapping mission. The Service Module is still in lunar orbit.
The combined Service Module and capsule weighs 2,500 kg – 2.5 tons, Stooke said, so it can’t sit on top of the rocket’s fuel tanks. I can’t guess the mass [of the payload adapter] but it can be very important.
Payload adapters for medium-sized payloads can weigh anywhere from 135 Kg (300 lbs.) to 225 kg (500 lbs) or more.
Chang’e 5-T1 also has additional payloads, but they are small (and known to be onboard) and cannot account for a mass large enough to create a second crater. The two payloads were small radiation exposure experiments for bacteria and plants, as well as the first commercial payload on the Moon called the 4M mission (Manfred Memorial Moon Mission) for the German space technology company OHB System, in honor of the founder of company, Manfred Fuchs, who died in 2014. The payload weighed only 14 kilograms but contained two scientific instruments: a radio beacon to test a new way of locating the spacecraft and a radiation dosimeter (provided by the Spanish company iC-Mlaga) to continuously measure radiation levels. throughout the satellite’s circumlunar journey. The 4M mission is mounted in the booster’s equipment bay.
There is no reason to suspect that the rocket has anything else attached to it other than the 4M and the usual flight electronics, said citizen scientist Scott Tilley, who monitors the orbits of artificial Earth satellites and Moon. There is also some additional mass to support the payload adapter and related structure for supporting the payload stack, which is likely at the limit of the rocket’s capabilities. Consider that this was the first mission they launched to the Moon with a payload. It can be more complicated to mount and secure than other payloads, which are more self-contained.
The ongoing debate on the extra mass and what it would have been if not for two things: the unusual double crater created by these impact boosters and the denial by Chinese foreign ministry officials that the space junk and the impact from their rocket. They insisted that the Change 5T-1 rocket had burned up when it returned to Earth in 2014. However, on March 1, 2022, the US Department of Defenses Space Command, which tracks low-Earth orbit space junk, released a statement saying that Chinas 2014 rocket never de-orbited.
In addition, Chinese officials have yet to comment on the nature of the double hole.
The crater was imaged by NASAs Lunar Reconnaissance Orbiter (LRO).
Typically, a spent rocket has its mass concentrated at the end of the motor; The remaining stage of the rocket mainly consists of an empty fuel tank, wrote Mark Robinson, principal investigator of the LRO Camera (LROC), in June of 2022 when the images were released.
A research team from the University of Arizona discovered the errant booster (it was initially believed to be an asteroid), tracking its movements to determine that it was from the Change 5-T1 mission. They also performed a spectroscopic analysis of the object from ground-based telescope observations during several Earth flybys, which showed the object to be the Long March 3C rocket body from the Change 5-T1 mission. They were able to predict where and when the booster would impact the Moon, so the LRO team could quickly find the impact crater in their data.
Everyone was surprised by the impact that created a double crater. No other impact of the rocket body on the Moon has created double craters, as seen in these pictures of the craters from the four Saturn rocket boosters from Apollos 13, 14, 15, 17.
Researchers from the University of Arizona said there should be additional, unexposed mass at the front end of the rocket body.
The results from the Bayesian analysis imply that there may be more mass at the front of the rocket body, wrote Tanner Campbell, Vishnu Reddy and others in their paper Physical Characterization of Moon Impactor WE0913A. A comparison of pre- and post-impact images of the location shows two distinct side craters created by Change 5-T1 R/B. The double crater supports the hypothesis that there is additional mass at the front end of the rocket body, opposite the engines, in excess of the published mass of the secondary permanently attached payload.
Asked about the payload adapter as a possible cause of the excess mass, team member Vishnu Reddy didn’t want to venture a guess without more data.
“It’s hard to predict the support structure because we don’t know anything like that with conventional boosters sent to the Moon,” he said.
Tilley told Universe Today that among amateur and professional satellite and rocket trackers, it is known that the Chinese space agency has struggled in the past with their goal of having these types of boosters re-enter the Earth’s atmosphere or ejected from the Earth-Moon. proper disposal system.
The Chinese expect the rocket to re-enter the Earth’s atmosphere, Tilley explained, noting the details in a paper by LuxSpace, the company operating the 4M mission. That didn’t happen so it seems part of their mission failed, which the Chinese probably denied it was their rocket later.
Subsequently, however, more recent missions, such as the booster for the Chang’e 5 sample return mission successfully re-entered the Earth’s atmosphere and were properly disposed of.
Another question about the effect is to understand the dynamics of why a booster, even if it has a lot of weight on each end, will make a double hole.
Regarding the double crater, Vishnu explained, I think the booster was impacted at a near vertical angle, so the engines created the first crater and the secondary mass fell and created the second crater. Vishnu added, it is also possible that if the booster was tumbling and coincidentally horizontal when it hit, it could have created two craters.
But as with most of this incredible space drama story, questions still remain.
So we leave the actual mechanism for a future paper when we have better model data, Vishnu said.
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