Washington, September 4 : A new research is aiming to unmask some Near Earth Objects (NEOs), which are comets posing as asteroids.
NEOs are objects whose orbits bring them in close proximity to Earth.
Some NEOs could be dying comets, those that have lost most of the volatile materials that create their characteristic tails.
Others could be dormant and might again display comet-like features after colliding with another object, according to Paul Abell, a Houston, Texas-based research scientist with the Planetary Science Institute.
Abell is using NASA's Infrared Telescope Facility at the Mauna Kea Observatories in Hawaii and the MMT telescope on Mount Hopkins, south of Tucson, Arizona, to uncover observational signatures that separate extinct/dormant comets from near-Earth asteroids.
This is important for a couple of reasons.
First, dormant comets in near-Earth space could become supply depots to support future exploration activities with water and other materials.
Second, like other NEOs, they could pose a threat to Earth if they are on a collision course with our planet.
Third, they can provide data on the composition and early evolution of the solar system because they are thought to contain unmodified remnants of the primordial materials that formed the solar system.
Low-activity, near-earth comets flashed onto the planetary-science radar screen in 2001, when NEO 2001 OG108 was discovered by the Lowell Observatory Near Earth Asteroid Search telescope.
It had an orbit similar to comets coming in from the Oort Cloud and was first thought to be one of the Damocloids, asteroids that have Comet Halley-type orbits, but no cometary tails.
Several groups began monitoring 2001 OG108 because it looked suspiciously comet-like.
The nuclei of comets are very dark and difficult to observe when they're far from Earth.
When they come closer to Earth, the sun's heat vaporizes some of the comet's ice, creating the clouds of dust and gas that make up the comet's coma and tail, which shroud the nucleus from view.
The coma is a bright cloud of dust and gas at the head of the comet, with the tail trailing out away from the Sun.
In early 2002, NEO 2001 OG108 lit up with a coma and it was re-classified as C/2001 OG108 (LONEOS).
"That's what started me on this line of reasoning and scientific investigation," Abell said.
For their investigation, Abell and Faith Vilas, director of the MMT Observatory and an affiliate senior scientist at the Planetary Science Institute, will be working in the visible and near-infrared spectral ranges.
"Hopefully, by combining data from these two wavelength regions, we may be able to find some signal or some observational discriminator that will help us identify whether something is an extinct comet or just an asteroid," Abell said.