The comet we tracked and observed close in 2005 is doing aswing past the sun and we will see what happens after the pass and be able tocompare it to these before images.
Expect lots of great images. We will do our best to post them in a timely fashion. Otherwise check the NASA feed.
It would be interesting to ride a comet as an imbeddedobserver down close to the sun’s surface with robotic sensing gear. Perhaps a few decades from now we can try allthat.
NASA Spacecraft Closes in on Comet Tempel 1
February 9, 2011: NASA is about to discover how solar heat devours acomet.
Stardust-NExT chases a comet, an artist's concept.
"For the first time, we'll see the same comet before and after itsclosest approach to the sun," explains Joe Veverka, principal investigatorfor NASA's Stardust-NExT mission.
The comet is Tempel 1, which NASA's Deep Impact probe visited in 2005.Now another NASA spacecraft, Stardust-NExT, is closing in for a second look onValentine's Day, Feb. 14, 2011. The two visits bracket one complete orbit ofthe comet around the sun--and a blast of solar heat.
"Close encounters with the sun never go well for a comet,"says Veverka. "Fierce solar heat vaporizes the ices in the comet's core,causing it to spit dust and spout gas. The cyclic loss of material eventuallyleads to its demise."
Researchers suspect the flamboyant decay doesn't happen evenly all overa comet's surface*, but until now they've lacked a way to document where,exactly, it does occur. Stardust NExT will image some of the same surface areasDeep Impact photographed 6 years ago, revealing how these areas have changedand where material has been lost.
"Deep Impact gave us tantalizing glimpses of Temple
At a January 2011 press conference, Veverka and other Stardust-NExTteam members listed the features they're most interested in seeing again:
For starters, parts of the comet's surface are layered like pancakes.
"Earth has layers because water and wind move dirt and debrisaround here, but layering on a comet was a surprise – and a mystery," saysVeverka.
Pancake-layers and a possible powdery flow are among the surfacefeatures of interest highlighted in this July 4, 2005, Deep Impact photo ofComet Tempel 1. The bright flash is where Deep Impact dropped an 820 lb copperprojectile onto the comet. Stardust-NExT could get a first look at theaftermath of the blast. [more]
"One idea is that two protocometary bodies collided at low speedsand smushed together to form something like a stack of flapjacks," saysPete Shultz, Stardust-NExT co-investigator.
Is that right? Data obtained by Stardust-NExT will provide clues andpossibly reveal what made the "comet pancakes."
Another area intrigues the research team even more.
"There's a large plateau that looks like a flow," says Shultz."If it really is a flow, it means there was recently gas and dustemanating from the [surface]."
Stardust-NExT will reveal how the plateau has changed (Is it flowing?),helping the team determine its origin. Whatever their origin, the plateau andlayering show that comets have a much more complicated geologic history thanpreviously thought.
A close-up view of a possible flow on Tempel 1. [more]
"Tempel 1 is not just a fuzzy ball," says Shultz. "Ithas history."
It's a history NASA has had a hand in. During its 2005 visit, DeepImpact dropped an 820-pound projectile into the comet's core. In a developmentthat surprised mission scientists, the impact excavated so much material thatthe underlying crater was hidden from view. Deep Impact's cameras were unableto see through the enormous cloud of dust the impactor had stirred up. StardustNExT could provide a long anticipated look at the impact site.
"The dust has settled there, so if the right part of the comet isfacing us, we could see the crater and learn its size," says Veverka."That would answer some key questions. For instance, is a comet's surfacehard or soft?"
In a future mission, a spacecraft may land on a comet and gathersamples for analysis. To design a suitable lander, researchers need to knowwhat kind of surface it would land on. They'll also need to know which tools tosend – drills for hard surfaces or scoops for something softer.
Like Deep Impact, the Stardust spacecraft has already had a productivecareer. Launched in 1999, it approached Comet Wild 2 close enough in 2004 toimage its feature-rich surface and even gather dust particles from the comet'satmosphere. (A key finding in the sample was the amino acid glycene – abuilding block of life.)
"We could have just let this old spacecraft rest on those laurels,leaving it to forever orbit the sun," says Veverka. "But instead,we're doing first-class comet science with it -- again."
As for Tempel 1, a hungry sun awaits.
No comments:
Post a Comment