"2003 YN107 arrived in 1999," says Paul Chodas of NASA's Near Earth Object Program at JPL, "and it's been corkscrewing around Earth ever since." Because the asteroid is so small and poses no threat, it has attracted little public attention. But Chodas and other experts have been monitoring it. "It's a very curious object," he says.
Most near-Earth asteroids, when they approach Earth, simply fly by. They come and they go, occasionally making news around the date of closest approach. 2003 YN107 is different: It came and it stayed.
"We believe 2003 YN107 is one of a whole population of near-Earth asteroids that don't just fly by Earth. They pause and corkscrew in our vicinity for years before moving along."
These asteroids are called Earth Coorbital Asteroids or "coorbitals" for short. Essentially, they share Earth's orbit, going around the Sun in almost exactly one year. Occasionally a coorbital catches up to Earth from behind, or vice versa, and the dance begins: The asteroid, while still orbiting the sun, slowly corkscrews around our planet.
"These asteroids are not truly captured by Earth's gravity," notes Chodas. "But from our point of view, it looks like we have a new moon."
Astronomers know of at least four small asteroids that can do this trick: 2003 YN107, 2002 AA29, 2004 GU9 and 2001 GO2. "There may be more," says Chodas. He believes the list will grow as asteroid surveys improve in sky coverage and sensitivity.
At the moment, only two coorbitals are actually nearby: 2003 YN107 and 2004 GU9. The others are scattered around Earth's orbit.
2004 GU9 is perhaps the most interesting. It measures about 200 meters across, relatively large. And according to calculations it has been corkscrewing around Earth for 500 years--and may continue for another 500. It's in a remarkably stable "orbit."
Right now, however, researchers are paying more attention to 2003 YN107 for one simple reason: it's about to depart. The asteroid's corkscrew path is lopsided and on June 10th it will dip within 3.4 million km of Earth, slightly closer than usual. Earth's gravity will then give the asteroid the nudge it needs to leave.
"This is a chance to observe one of these asteroids [on the way out]," explains Chodas.
It won't be gone forever. In about 60 years 2003 YN107 will lap Earth again, resuming its role as a temporary, corkscrewing moonlet. In due course, other coorbitals will do the same.
Each encounter is an opportunity for study--and possibly profit. Even the most powerful telescopes cannot see much of these tiny asteroids; they're just specks in the eyepiece. But one day, when the space program is more advanced, it might be possible to visit, explore the moonlets and tap their resources. "For now, they're just a curiosity," says Chodas.
News flash: Earth is about to lose a moon. More to come.
Source: Science@NASA, by Dr. Tony Phillips
Related stories:
ESA wants International Space Station to live longer
The European Space Agency (ESA) on Tuesday said it hoped the International Space Station (ISS), whose operational life beyond 2015 remains uncertain, would continue working until at least 2020.
Team sets records in simulating seismic wave propagation across the Earth
A team led by researchers at the San Diego Supercomputer Center at UC San Diego has successfully completed record-setting, petascale-level simulations of the earth's inner structure, paving the way for seismologists to model seismic wave propagations at frequencies of just over one second – the same frequencies that occur in nature.
Beta Pictoris planet finally imaged?
(PhysOrg.com) -- The hot star Beta Pictoris is one of the best-known examples of stars surrounded by a dusty 'debris' disc. Debris discs are composed of dust resulting from collisions among larger bodies like planetary embryos or asteroids. They are a bigger version of the zodiacal dust in our Solar System. Its disc was the first to be imaged — as early as 1984 — and remains the best-studied system. Earlier observations showed a warp of the disc, a secondary inclined disc and infalling comets onto the star. "These are indirect, but tell-tale signs that strongly suggest the presence of a massive planet lying between 5 and 10 times the mean Earth-Sun distance from its host star," says team leader Anne-Marie Lagrange. "However, probing the very inner region of the disc, so close to the glowing star, is a most challenging task."
Happy Birthday: Space station celebrates 10 years
(AP) -- NASA couldn't have staged it any better: 10 people in orbit for Thursday's 10th anniversary of the world's most elaborate and expensive housing project, the international space station.
Dog helps track mystery of orcas' decline
Researchers trying to learn whether orcas are starving have turned - with the help of a dog - to a new source of information: orca scat.
International Space Station turns 10
The International Space Station, one of the most ambitious space projects ever and a key launching board for exploration of the solar system, including Mars and beyond, turns 10 years old Thursday.
Water vapor confirmed as major player in climate change
(PhysOrg.com) -- Water vapor is known to be Earth's most abundant greenhouse gas, but the extent of its contribution to global warming has been debated. Using recent NASA satellite data, researchers have estimated more precisely than ever the heat-trapping effect of water in the air, validating the role of the gas as a critical component of climate change.
Value of satellites recognized for conserving wetlands
Wetlands contribute to our lives in remarkable ways by providing food and water, controlling floods, protecting against storms and supporting biodiversity, yet they are experiencing loss and degradation on a massive scale.
