APOD: Comet Tempel 1 from Stardust NeXT... (2011 Feb 16)

APOD Robot · Post by **APOD Robot** » Wed Feb 16, 2011 5:06 am

Comet Tempel 1 from Stardust NeXT Spacecraft

Explanation: No comet has ever been visited twice before. Therefore, the unprecedented pass of the Stardust-NeXT spacecraft near Comet Tempel 1 earlier this week gave humanity a unique opportunity to see how the nucleus of a comet changes over time. Changes in the nucleus of Comet Tempel 1 were of particular interest because the comet was hit with an impactor from the passing Deep Impact spacecraft in 2005. Pictured above is one digitally sharpened image of Comet Tempel 1 near the closest approach of Stardust-NeXT. Visible are many features imaged in 2005, including craters, ridges, and seemingly smoother areas. Few firm conclusions are yet available, but over the next few years astronomers who specialize in comets and the understanding the early Solar System will be poring over these images looking for new clues as to how Comet Tempel 1 is composed, how the 2005 impact site now appears, and how general features of the comet have evolved.

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Beyond · Post by **Beyond** » Wed Feb 16, 2011 5:44 am

ha-ha, this APOD really has a bad hair day! It also has a bad arrow day. I wanted to see what the impact site looks like. There's arrows A & B. It says that the third big arrow is pointing to the impact site. THERE IS NO BIG THIRD ARROW!! Where's Robin Hood when you need him??

Chris Peterson · Post by **Chris Peterson** » Wed Feb 16, 2011 5:54 am

Beyond wrote:ha-ha, this APOD really has a bad hair day! It also has a bad arrow day. I wanted to see what the impact site looks like. There's arrows A & B. It says that the third big arrow is pointing to the impact site. THERE IS NO BIG THIRD ARROW!! Where's Robin Hood when you need him??

Sure there is. Did you look at the full image? The "b" arrow is off the edge of the cropped thumbnail on the page the link points to. (And the image with the arrows isn't an APOD.)

: Click to view full size image

quadibloc · Post by **quadibloc** » Wed Feb 16, 2011 6:05 am

I followed the link in the article below the picture; apparently, the spacecraft is Stardust-NExT; the "next" part doesn't have the same capitalization as the black cube from Steve Jobs.

Timothy · Post by **Timothy** » Wed Feb 16, 2011 6:23 am

It is spelled 'poring', not 'pouring'.

isoparix · Post by **isoparix** » Wed Feb 16, 2011 8:48 am

Timothy wrote:It is spelled 'poring', not 'pouring'.

Quite. "pouring over these images". Pouring what, exactly?

Ann · Post by **Ann** » Wed Feb 16, 2011 10:27 am

Wow. Seeing a "barefaced" comet without its light show is like seeing a Hollywood star without makeup.

Ann

robt · Post by **robt** » Wed Feb 16, 2011 12:52 pm

Yes, please change the word to "poring"!

Beyond · Post by **Beyond** » Wed Feb 16, 2011 1:13 pm

Ok Chris, just where did you find the full version with all three arrows?? Nothing I've clicked on so far has the three Big arrows.

NeilS · Post by **NeilS** » Wed Feb 16, 2011 1:15 pm

I thought that Comet Halley had been visited by at least 3 probes.

Beyond · Post by **Beyond** » Wed Feb 16, 2011 1:18 pm

Ann wrote:Wow. Seeing a "barefaced" comet without its light show is like seeing a Hollywood star without makeup.

Ann

Ann, You've just made a non-colorful comment

WOW!

neufer · Post by **neufer** » Wed Feb 16, 2011 2:17 pm

NeilS wrote:
I thought that Comet Halley had been visited by at least 3 probes.

But Giotto was the only one to have a really close encounter.

http://en.wikipedia.org/wiki/Halley_Armada wrote:
<<The Halley Armada is the generally accepted and popularly used name of five space probes sent to examine Halley's Comet during its 1986 sojourn through the inner solar system, connected with apparition "1P/1982 U1". The armada consisted of one probe from the European Space Agency, two probes that were joint projects between the Soviet Union and France and two probes from the Institute of Space and Astronautical Science of Japan. Without the measurements from the other space probes, Giotto's closest distance would have been 4,000 km instead of the 596 km achieved.

Probes involved (in order of closest approach):

* Giotto, the first space probe to get close-up color images of the nucleus of a comet. (ESA)
* Vega 1, which dropped a balloon probe and lander on Venus before going on to Halley. (USSR/France Intercosmos)
* Vega 2, which dropped a balloon probe and lander on Venus before going on to Halley. (USSR/France Intercosmos)
* Suisei, also known as PLANET-A. Data from Sakigake was used to improve upon Suisei for its dedicated mission to study Halley. (ISAS)
* Sakigake, Japan's first probe to leave the Earth system, mainly a test of interplanetary mission technology. (ISAS)
Other space probes had their instruments examining Halley's Comet:

* Pioneer 7 was Launched on August 17, 1966. It was put into heliocentric orbit with a mean distance of 1.1 AU to study the solar magnetic field, the solar wind, and cosmic rays at widely separated points in solar orbit.On 20 March 1986, the spacecraft flew within 12.3 million kilometers of Halley's Comet and monitored the interaction between the cometary hydrogen tail and the solar wind.

* Pioneer Venus Orbiter in orbit of Venus, was positioned perfectly to take measurements of Halley's Comet during its perihelion February 9, 1986. Its UV-spectrometer observed the water loss when Halley's Comet was difficult to observe from the Earth.

* International Cometary Explorer, which was repurposed as a cometary probe in 1982 and visited Comet Giacobini-Zinner in 1985, transited between the Sun and Halley's Comet in late March 1986 and took measurements.>>

neufer · Post by **neufer** » Wed Feb 16, 2011 2:24 pm

http://en.wikipedia.org/wiki/Temple-1 wrote:
Detail of crater-like features on Comet Tempel 1 in image taken by Deep Impact's impactor [[b][color=#FF0000]belated Valentine[/color][/b]] Impact point will be just below [b][color=#FF00FF]dark pimple-like feature[/color][/b] [img]http://upload.wikimedia.org/wikipedia/en/7/72/Logo_clearasil.png[/img]

Ann wrote:
Seeing a "barefaced" comet without its light show
is like seeing a Hollywood star without makeup.
Crater-like features taken by Deep Impact's impactor

'Before and after' comparison images from Deep Impact and Stardust, showing the crater formed by Deep Impact on the right hand image.

bystander · Post by **bystander** » Wed Feb 16, 2011 2:55 pm

Beyond wrote:where did you find the full version with all three arrows??

2005 impact site + Full image and caption

deathbed rider · Post by **deathbed rider** » Wed Feb 16, 2011 4:33 pm

The Earth must has been full of craters before it was coated

Chris Peterson · Post by **Chris Peterson** » Wed Feb 16, 2011 5:00 pm

deathbed rider wrote:The Earth must has been full of craters before it was coated

Coated?

Earth has always had a thick atmosphere, so it is doubtful it ever had more than a few craters at any time- and nearly all of those from large (and therefore rare) impacts.

NoelC · Post by **NoelC** » Wed Feb 16, 2011 11:13 pm

Okay, call me stupid, but...

We impact the thing with a high speed collision, and there's nothing significant to show for it?

I'll admit to really wanting to see the damage. I was let down!

Why not send a powerful bomb and make an actual sizable hole in it? Concern over contaminating the ejecta? Okay, maybe nuking the thing might be a bit extreme, but c'mon already! No visible mark?

Maybe hit it with a whole bunch of 'em and carve a message in it.

I think perhaps I've been watching too much Mythbusters.

-Noel

Chris Peterson · Post by **Chris Peterson** » Wed Feb 16, 2011 11:40 pm

NoelC wrote:We impact the thing with a high speed collision, and there's nothing significant to show for it?

What's "significant"? There is a visible crater; I think that's significant.

Why not send a powerful bomb and make an actual sizable hole in it? Concern over contaminating the ejecta? Okay, maybe nuking the thing might be a bit extreme, but c'mon already!

The concern with contamination is very real. But aside from that, there's the simple question of practicality. Deep Impact hit the comet with a 370 kg probe traveling 10.2 m/s. That means it released 1.9e10 J, or the equivalent of 4.5 tons of TNT. So the kinetic energy of the probe was twelve times greater than the equivalent mass of TNT. What kind of explosive should they send? How much would it add to the cost of the mission to transport all that mass? Is there any explosive that would come close to releasing the energy of the kinetic collision alone? Realistically, probably not.

The Deep Impact probe resulted in something on the order of 20 million kg of water and dust being ejected. It made a crater 150 meters across. That's pretty significant.

owlice · Post by **owlice** » Thu Feb 17, 2011 2:34 am

NoelC wrote: Maybe hit it with a whole bunch of 'em and carve a message in it.

Kilroy was here, perhaps?

Maybe better: Property of the Hells Angels

neufer · Post by **neufer** » Thu Feb 17, 2011 3:41 am

NoelC wrote:
Why not send a powerful bomb and make an actual sizable hole in it?

Maybe hit it with a whole bunch of 'em and carve a message in it.

WE CAME IN PEACE FOR ALL MANKIND

Ann · Post by **Ann** » Thu Feb 17, 2011 4:20 am

neufer wrote:
NoelC wrote:
Why not send a powerful bomb and make an actual sizable hole in it?

Maybe hit it with a whole bunch of 'em and carve a message in it.

WE CAME IN PEACE FOR ALL MANKIND

And then, you know, a sizable fragment of the poor comet could ricochet our way and hit us.

That would be a peaceful inter-solar system body exchange, for sure!

Ann

biddie67 · Post by **biddie67** » Thu Feb 17, 2011 4:35 am

APOD Robot wrote: ...... over the next few years astronomers who specialize in comets and the understanding the early Solar System ....

I've seen references to comets holding clues to the early Solar System several times in the past but I don't seem to get why that might be so. To me if something is in our "vicinity", it must have originated in the same general time span as the planets themselves.

Why do astronomers think that comets might hold clues that the Sun or planets don't also have?

Ann · Post by **Ann** » Thu Feb 17, 2011 4:53 am

biddie67 wrote:
APOD Robot wrote: ...... over the next few years astronomers who specialize in comets and the understanding the early Solar System ....
I've seen references to comets holding clues to the early Solar System several times in the past but I don't seem to get why that might be so. To me if something is in our "vicinity", it must have originated in the same general time span as the planets themselves.

Why do astronomers think that comets might hold clues that the Sun or planets don't also have?

Well... if I understand it correctly, comets are believed to have formed in the outer parts of the solar system and mostly stayed there, too, where they might be relatively unchanged since the time they were formed. Objects closer to the Sun are supposed to have changed, mostly because of ultraviolet irradiation from the Sun.

Ann

glaucoramalho · Post by **glaucoramalho** » Thu Feb 17, 2011 11:48 am

Hi people! Good Morning from Brazil!

I was looking for distant pictures of Tempel 1 to see how it looks like at a distance, and what I found was a huge Celestial Dragon across the sky with a big corona and tail, not this dry rock pictures NASA released last Monday.

Comparing the photos of Deep Impact mission (with no water or ice in any known form and no jets coming out of the nucleus at all), how is that possible for a so small asteroidal object to exhibit a so well formed tail and corona for at least 144 years from its discovery (maybe thousands and thousands of years), with no known source of energy??

I'm sending my sources for your review and comments:

http://www.nasa.gov/mission_pages/stard ... index.html
http://www.nasa.gov/mission_pages/deepi ... tures.html
http://www.scienceinschool.org/reposito ... _large.jpg

Cheers!

biddie67 · Post by **biddie67** » Thu Feb 17, 2011 12:32 pm

Thanks Ann -

Starship Asterisk*

APOD: Comet Tempel 1 from Stardust NeXT... (2011 Feb 16)

APOD: Comet Tempel 1 from Stardust NeXT... (2011 Feb 16)

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