Catching a Comet
|Comet Wild 2 imaged just after flyby. The image highlights the remarkably rugged surface of the comet, which in close-up stereo views shows hardened impact craters, cliffs, and mesas in the landscape. |
Six years ago, then NASA Associate Administrator Wesley Huntress, Jr., stated , "Wherever liquid water and chemical energy are found, there is life. There is no exception." Few opportune years like 2004 have presented astrobiology with as many remarkable vistas and fresh perspectives on this fundamental triad of water, chemical energy and life.
Consider this year’s accomplishments of those dedicated to searching for life in the universe.
Landing on Mars not once, but twice. Then finding evidence for water on opposite sides of the red planet. Picking up what appears to be methane signals in the martian atmosphere, one of the residues that might prove one day to be the product of underground biology. Scientists began to discuss seriously what colonization strategies make sense.
Flying through the tail of a comet and heading home after collecting the first extraterrestrial samples from such dusty iceballs. Launching the Deep Impact probe to smash into a comet and watch how the dust and ice get kicked up.
|Comet Halley imaged by European flyby. |
Filling the astronomy catalogs with well over a hundred new planets, including what may prove to be the first visible exoplanet. Finding some nearby candidates that might occupy temperate locations or safely orbit Sun-like stars.
The editors of Astrobiology Magazine revisit the highlights of the year and where possible point to one of the strongest lineups ever for beginning a new turn of the calendar. Between the marathon still being run by the twin Mars rovers and the expected descent to Saturn’s moon, Titan, next year promises no letdowns.
Number five on the countdown of 2004 highlights was Stardust mission and exploration of comets.
|Stardust spacecraft beaming back its images soon after surviving its Wild- 2 comet encounter. |
Comets may have played a major role in the origin of life on Earth, delivering a significant share of the Earth’s water as well as carbon-rich organic compounds. When the Stardust spacecraft passed within 236 kilometers (147 miles) of the comet Wild 2 on January 2, 2004, it encountered a storm of dust particles traveling at over 6 times the speed of a bullet. The spacecraft collected some of the hundreds of thousands of particles that impacted each second, and this sample will be returned to Earth in January 2006.
When Stardust’s Sample Return capsule containing the comet particles arrives on Earth in 2006, it will be sent to NASA’s Johnson Space Center in Houston for analysis. Because comets are composed of ice, dust, and gas – the building blocks of the solar system – particles collected from a comet may be able to tell us something about how the solar system formed.
There are two more comet missions currently planned. NASA’s Deep Impact mission will visit the comet Tempel 1 on July 4, 2005. The European Space Agency’s Rosetta mission launched in March of 2004 and will reach the comet Churyumov-Gerasimenko in November 2014.
- Mars Reconnaissance Orbiter (MRO) launch, Mars Orbiter to collect high-resolution, 1-meter, images in stereo-view of Mars
- European Venus Express, Venus Orbiter for two-year nominal mapping life [486 days, two Venus year]
- New Horizons, Pluto and moon Charon flyby, mapping to outer solar system cometary fields and Kuiper Belt
- Dawn, Asteroid Ceres and Vesta rendezvous and orbiter, including investigations of asteroid water and influence on meteors
- Kepler, Extrasolar Terrestrial Planet Detection Mission, designed to look for transiting or earth-size planets that eclipse their parent stars [survey 100,000 stars]
- Europa Orbiter, planned Orbiter of Jupiters ice-covered moon, Europa, uses a radar sounder to bounce radio waves through the ice
- Japanese SELENE Lunar Orbiter and Lander, to probe the origin and evolution of the moon
- Japanese Planet-C Venus Orbiter, to study the Venusian atmosphere, lightning, and volcanoes.
- Mars Scout mission, final selections August 2003 from four Scouts: SCIM, ARES, MARVEL and Phoenix
- French Mars Remote Sensing Orbiter and four small Netlanders, linked by Italian communications orbiter
- BepiColumbo, European Mercury Orbiters and Lander, including Japanese collaborators, lander to operate for one week on surface
- Mars 2009, proposed long-range rover to demonstrate hazard avoidance and accurate landing dynamics
Related Web Pages
2003: Year in Review
Solar System Exploration Survey
Mars Opportunity Rover
Mars Spirit Rover
Planet Ten: Beyond Pluto?