NASA Television will provide commentary starting at 11 a.m. PST (2 p.m. EST) on Friday, Feb. 15, during the close, but safe, flyby of a small near-Earth asteroid named 2012 DA14. NASA places a high priority on tracking asteroids and protecting our home planet from them. This flyby will provide a unique opportunity for researchers to study a near-Earth object up close.
The half-hour broadcast from NASA's Jet Propulsion Laboratory in Pasadena, Calif., will incorporate real-time animation to show the location of the asteroid in relation to Earth, along with live or near real-time views of the asteroid from observatories in Australia, weather permitting.
At the time of its closest approach to Earth at approximately 11:25 a.m. PST (2:25 p.m. EST / 19:25 UTC), the asteroid will be about 17,150 miles (27,600 kilometers) above Earth's surface. The commentary will be available via NASA TV and streamed live online at: * http://www.nasa.gov/ntv * and http://www.ustream.tv/nasajpl2.
This past November, Two NASA astronomers suggested that the size and location of an asteroid belt, shaped by the evolution of the sun's planet-forming disk and by the gravitational influence of a nearby giant Jupiter-like planet, may determine whether complex life will evolve on an Earth-like planet.
Rebecca Martin, a NASA Sagan Fellow from the University of Colorado in Boulder, and astronomer Mario Livioof the Space Telescope Science Institute have concluded that Solar systems with life-bearing planets may be rare if they are dependent on the presence of asteroid belts of just the right mass.
"Our study shows that only a tiny fraction of planetary systems observed to date seem to have giant planets in the right location to produce an asteroid belt of the appropriate size, offering the potential for life on a nearby rocky planet," said Martin, the study's lead author. "Our study suggests that our solar system may be rather special."
Martin and Livio suggest that the location of an asteroid belt relative to a Jupiter-like planet is not an accident. The asteroid belt in our solar system, located between Mars and Jupiter, is a region of millions of space rocks that sits near the "snow line," which marks the border of a cold region where volatile material such as water ice is far enough from the sun to remain intact.
When Jupiter formed just beyond the snow line, its powerful gravity prevented nearby material inside its orbit from coalescing and building planets. Instead, Jupiter's influence caused the material to collide and break apart. These fragmented rocks settled into an asteroid belt around the sun.
"To have such ideal conditions you need a giant planet like Jupiter that is just outside the asteroid belt [and] that migrated a little bit, but not through the belt," Livio explained. "If a large planet like Jupiter migrates through the belt, it would scatter the material. If, on the other hand, a large planet did not migrate at all, that, too, is not good because the asteroid belt would be too massive. There would be so much bombardment from asteroids that life may never evolve."
Using our solar system as a model, Martin and Livio proposed that asteroid belts in other solar systems would always be located approximately at the snow line. To test their proposal, Martin and Livio created models of planet-forming disks around young stars and calculated the location of the snow line in those disks based on the mass of the central star.
They then looked at all the existing space-based infrared observations from the Spitzer Space Telescope of 90 stars having warm dust, which could indicate the presence of an asteroid belt-like structure. The temperature of the warm dust was consistent with that of the snow line. "The warm dust falls right onto our calculated snow lines, so the observations are consistent with our predictions," Martin said.
The duo then studied observations of the 520 giant planets found outside our solar system. Only 19 of them reside outside the snow line. This suggests that most of the giant planets that may have formed outside the snowline have migrated too far inward to preserve the kind of slightly dispersed asteroid belt needed to foster enhanced evolution of life on an Earth-like planet near the belt. Apparently, less than four percent of the observed systems may actually harbor such a compact asteroid belt.
"Based on our scenario, we should concentrate our efforts to look for complex life in systems that have a giant planet outside of the snow line," Livio said.
The illustration below shows three possible scenarios for the evolution of asteroid belts. In the top panel, a Jupiter-size planet migrates through the asteroid belt, scattering material and inhibiting the formation of life on planets. The second scenario shows our solar-system model: a Jupiter-size planet that moves slightly inward but is just outside the asteroid belt. In the third illustration, a large planet does not migrate at all, creating a massive asteroid belt. Material from the hefty asteroid belt would bombard planets, possibly preventing life from evolving.
New research based on an analysis of theoretical models and archival observations, including infrared data from NASA's Spitzer Space Telescope, suggests that the second scenario may also be important for the development of life in other solar systems.
The Sagan Fellowship Program is administered by the NASA Exoplanet Science Institute at theCalifornia Institute of Technology in Pasadena, Calif., whose purpose is to advance the scientific and technical goals of NASA's Exoplanet Exploration Program.
For this Friday's NEO flyby, in addition to the commentary, near real-time imagery of the asteroid's flyby before and after closest approach, made available to NASA by astronomers in Australia and Europe, weather permitting, will be streamed beginning at about 9 a.m. PST (noon EST) and continuing through the afternoon at the following website http://www.ustream.tv/nasajpl2
A Ustream feed of the flyby from a telescope at NASA's Marshall Space Flight Center in Huntsville, Ala., will be streamed for three hours starting at 6 p.m. PST (8 p.m. CST / 9 p.m. EST). To view the feed and ask researchers questions about the flyby via Twitter, visit: http://www.ustream.tv/channel/nasa-msfc
The NASA Near Earth Objects (NEO) Program at the agency's headquarters in Washington manages and funds the search, study and monitoring of NEOs, or asteroids and comets, whose orbits periodically bring them close to the Earth.
NASA's study of NEOs provides important clues to understanding the origin of our solar system. The objects also are a repository of natural resources and could become waystations for future exploration. In collaboration with other external organizations, one of the program's key goals is to search and hopefully mitigate potential NEO impacts on Earth.
For more information, including graphics and animations showing the flyby of 2012 DA14, visit: www.nasa.gov/asteroidflyby For more information about asteroids and near-Earth objects, visit: http://www.jpl.nasa.gov/asteroidwatch