A scenario has been identified that explains how the near - Earth asteroid Kamo’oalewa could have been knocked off the Moon and become what is known as a quasi - orbiter .
In the last two decades , astronomers have get a line the Earth is accompany through blank space not only by the Moon and the items we have put into domain , but object hump asquasi - satellites . Quasi - satellites lay out one of three categories of objects that co - orbit with our planet , also taking a year to travel around the Sun , but on a more elongated path . Their orbit are tied to our own to the extent that they never get all that far forth from Earth , at least until they shift into a different eccentric of co - orbit .
Among the quasi - satellites , Kamo’oalewa is possibly the most interesting , which is why China aims toland a spacecrafton it , launch in 2025 . First discovered in 2016 , at 45 - 60 meters ( 150 - 190 feet ) long , it ’s larger than the others and its orbit is more unchanging . Even though it presently never gets further than 10 time the length of the Moon away from us , it ’s only detectable by even the turgid telescopes briefly each year . At other time it ’s too far away , or too close to the instruction of the Sun .
Kamo’oalewa’s orbit keeps it always close to the Earth, but sometimes a little closer to the Sun and sometimes further away.Image credit: Tomruen viaWikimedia Commons(CC-By-SA 4.0)
Two years ago , grounds was presentedthat Kamo’oalewa ’s spectrum is the same as some Moon rocks , rather than the silicate asteroids it first appeared to resemble . The team who discovered this speculated it had been rap off the Moon when some declamatory asteroid crash into our companion . Nevertheless , even the authors of that paper admitted to considerable doubts , and simply view the idea more potential than any alternative they could propose .
Now the vitrine for Kamo’oalewa ’s lunar origins has been strengthened with an explanation of the circumstances in which an target could have been knocked off the Moon and strain its current orbit .
It ’s not strange for an objective to hit the Moon with such force that it launches piece into space . We’vefound meteoritesthat match the Moon rocks brought back by Apollo astronauts as a result . The same thing happens to the Earth , despite a protective atmospheric state and much larger gravitational force to overcome . However , the fragments would rarely end up in orbits similar to our own , and no one was trusted if this was even potential .
By modelling a large raiment of incoming speeds and the locations where anasteroidmight collide with , however , a team lead by Dr Aaron Rosengren of the University of California , San Diego showed it can materialize . They discover a 6.6 percentage chance conditions would be correct for the merchandise to be co - orbital with the Earth and Moon , most potential from an object murder the Moon ’s trailing hemisphere at just above the minimal speed required for ejecta to take to the woods lunar gravity . To become a quasi - satellite like Kamo’oalewa was less likely , however , at just 0.8 percent probability .
Although a slender fortune , that makes Kamo’oalewa ’s lunar line plausible , while an origin in the asteroid rap would be even less likely . A successful landing andsamplecollection would not only confirm Kamo’oalewa was once part of the Moon , but potentially match it to the accurate crater it come from , and therefore say us its age .
Meanwhile , this employment may aid us identify how likely it is that Kamo’oalewa , and perhaps other quasi - artificial satellite we have yet to discover , will escape their existing orbits and amaze a hazard to the Earth . In 300 yr , it is look that Kamo’oalewa will transition to a unlike socio-economic class of co - orbit , known as a horseshoe orbit , although it is ask to finally become a quasi - artificial satellite again .
" We necessitate more entropy to say with sure thing that Kamo’oalewa is indeed a shard of themoon , " Rosengren said in astatement , " And a outer space mission to this alone celestial torso is warranted . "
The field is published inCommunications Earth & Environment .
