Featured Research

from universities, journals, and other organizations

Instruments Aboard CONTOUR Spacecraft Will Provide First Surface "Fingerprint" Of Comet Nucleus

Date:
June 14, 2001
Source:
Cornell University News Service
Summary:
Instruments aboard a spacecraft that will be launched next year to explore two, and perhaps three or more, comets in the solar system will for the first time provide a "fingerprint" of the surface of cometary nuclei, giving the first firm evidence of the composition of the icy, rocky objects.

ITHACA, N.Y. -- Instruments aboard a spacecraft that will be launched next year to explore two, and perhaps three or more, comets in the solar system will for the first time provide a "fingerprint" of the surface of cometary nuclei, giving the first firm evidence of the composition of the icy, rocky objects.

Related Articles


About 50 of the world's leading comet experts, meeting at the Harvard Smithsonian Center for Astrophysics in Cambridge, Mass., recently, were told that the spacecraft's infrared imaging spectroscopy will map the composition of the nucleus of comet Encke at a resolution of 100 meters to 200 meters (109 to 218 yards), detailed enough to see craters and other large geologic features and to determine their composition.

Comet Encke will be the first target of NASA's Cornell University-led Comet Nucleus Tour (CONTOUR), scheduled for launch July 1, 2002. In a report prepared for the meeting, James Bell, Cornell assistant professor of astronomy and one of the scientists responsible for the spectrometer on the close-up imager, noted that the surface resolution of Encke's nucleus by the CONTOUR spectrometer will be even better than that obtained by the infrared spectrometer on the Near Earth Asteroid Rendezvous spacecraft during its recent orbital mission to asteroid 433 Eros. "The CONTOUR spacecraft will come within about 100 to 160 kilometers (62 to 100 miles) of the nucleus, although the exact distance is still in doubt because we don't know the orbital position of the nucleus with extreme precision," said Bell.

The imaging instrument, called the CONTOUR remote image/spectrograph, also will send back digital-camera images of Encke's nucleus. The camera will capture the images as the spacecraft speeds through the comet's dusty, gaseous head, called the coma, at 28 kilometers (about 17 miles) a second in November 2003. Joseph Veverka, Cornell professor of astronomy and principal investigator on the $155 million mission, noted at the Cambridge meeting that "success" will be defined as obtaining digital images of the nucleus showing automobile-size details, such as rocks, about 4 meters (4 yards) across. Encke, first discovered 225 years ago, is about 8 kilometers (5 miles) long and has an average radius of about 2.5 kilometers (1.5 miles). It orbits the sun once every 3.2 years, and its most recent apparition from Earth was last year. It is unique in that it has been observed from Earth on 56 of its apparitions, more than any other comet, including Halley.

Encke will not be the only comet on CONTOUR's agenda. In June 2006 the spacecraft is scheduled to encounter Comet Schwassmann-Wachmann 3 and, possibly, Comet d'Arrest in 2008. These targets are so-called "Jupiter family" comets because they are thought to have had their orbital periods shortened by previous gravitational encounters with the giant planet. The science team hopes it also might be possible to visit other kinds of comets, particularly primitive members of the so-called "dynamically young" family that are in long elliptical orbits and might be making one of their first close passes by the sun.

Cornell senior research associate and science team member Peter Thomas noted at the meeting that during the 30-minute flyby of the nucleus, the spacecraft's instruments "will be able to obtain detailed compositional measurements of gas and dust in the near-nucleus environment." The comet's coma is a vast but extremely thin atmosphere, approaching the size of the sun, consisting of gas and debris thrown off the nucleus as it orbits the sun. The peak of this shedding of material is reached as the comet approaches the sun, and all the spacecraft's flybys will occur when the target comet is near this point in its solar orbit.

The scientific team will be particularly searching the coma for evidence of curious particles previously detected in interstellar clouds by Jochen Kissel, a comet researcher at the Max-Planck-Institute for Extraterrestrial Physics in Garching, Germany. Kissel made his discovery in data sent back by NASA's Stardust mission, which will reach comet Wild 2 in 2004. The mission is using the same dust analyzer as will be carried by the CONTOUR. Said Veverka, "The particles have a completely weird composition and don't seem to have minerals in them but seem to be made of chains of carbon-hydrogen and oxygen-nitrogen, like polymers. But there isn't any polymer with that kind of composition that we are normally familiar with."

There is an indication, said Veverka, that some particles might have weathered the massive meltdown of material when the sun and planets were formed from interstellar dust and clouds. "The question now is, have any of these particles been preserved in comets? We have to get close enough to a comet to find out." Although Encke has been much studied from ground-based observatories, little is known about its composition, which is why the comet experts gathered to exchange information on the object. Most assumptions about Encke, the researchers agreed, are drawn from data gathered by the European Space Agency's Giotto spacecraft, which visited comet Halley in 1986. Much of what astronomers know about comets "comes from the one object we've come close to, comet Halley," noted Casey Lisse, an astronomer at the University of Maryland. However, the CONTOUR images from Encke will be 25 times higher resolution than those from Halley.

Indeed, the most that the astronomers at the meeting could agree on was that Encke, some 30 million miles from Earth, is an extremely elongated "icy dirt ball" with a density, size, shape and rotation that defy precise analysis. Veverka wryly noted that the conflicting information about the comet is such that the mission will "not be dependent on any prejudices."

And science team member Anita Cochran, a research scientist at the McDonald Observatory, the University of Texas, ruefully concluded that "we started off by saying we didn't know, and we just made up things from there."

The complex journey of CONTOUR is shown in a computer simulation video, made for NASA by recent Cornell graduate Dan Maas, who previously produced a video for the 2003 Mars Rover mission. The new video can be seen on the CONTOUR web site at http://www.contour2002.org/


Story Source:

The above story is based on materials provided by Cornell University News Service. Note: Materials may be edited for content and length.


Cite This Page:

Cornell University News Service. "Instruments Aboard CONTOUR Spacecraft Will Provide First Surface "Fingerprint" Of Comet Nucleus." ScienceDaily. ScienceDaily, 14 June 2001. <www.sciencedaily.com/releases/2001/06/010614063503.htm>.
Cornell University News Service. (2001, June 14). Instruments Aboard CONTOUR Spacecraft Will Provide First Surface "Fingerprint" Of Comet Nucleus. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2001/06/010614063503.htm
Cornell University News Service. "Instruments Aboard CONTOUR Spacecraft Will Provide First Surface "Fingerprint" Of Comet Nucleus." ScienceDaily. www.sciencedaily.com/releases/2001/06/010614063503.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Space & Time News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Spokesman: 'NORAD Ready to Track Santa'

Spokesman: 'NORAD Ready to Track Santa'

AP (Dec. 19, 2014) Pentagon spokesman Rear Adm. John Kirby said that NORAD is ready to track Santa Claus as he delivers gifts next week. Speaking tongue-in-cheek, he said if Santa drops anything off his sleigh, "we've got destroyers out there to pick them up." (Dec. 19) Video provided by AP
Powered by NewsLook.com
NASA's Planet-Finding Kepler Mission Isn't Over After All

NASA's Planet-Finding Kepler Mission Isn't Over After All

Newsy (Dec. 18, 2014) More than a year after NASA declared the Kepler spacecraft broken beyond repair, scientists have figured out how to continue getting useful data. Video provided by Newsy
Powered by NewsLook.com
Rover Finds More Clues About Possible Life On Mars

Rover Finds More Clues About Possible Life On Mars

Newsy (Dec. 17, 2014) NASA's Curiosity rover detected methane on Mars and organic compounds on the surface, but it doesn't quite prove there was life ... yet. Video provided by Newsy
Powered by NewsLook.com
Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Reuters - US Online Video (Dec. 16, 2014) NASA's Mars Curiosity rover finds methane in the Martian atmosphere and organic chemicals in the planet's soil, the latest hint that Mars was once suitable for microbial life. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins