[X] My Assistant

[Chmee]

With the deep impact mission what they could have done was release the probe much sooner so that it would have impacted the comet several hours/days ahead of the main probe coming past it.

In that way we could have seen the impact crater after the "dust cleared". Problem with this of course would be targeting the impact probe precisely to the comet if it were released that far in advance of impact. Also, some of the science of the debris plume might be have benn degrade.

[djellison]

And of course, that means packing a bigger battery into the impactor, and a more powerfull transmitter. Which makes it heavier and bigger and so on and so forth....

Doug

[tty]

And it would have meant that the trajectories would have diverged more, so observations would have been from further away, unless you tweak the flyby craft's orbit, which requires additional fuel.....

tty

[abalone]

And it would have meant that the trajectories would have diverged more, so observations would have been from further away, unless you tweak the flyby craft's orbit, which requires additional fuel.....

tty

Not necessarily diverted more, the probe would have simply reduced delta V in the direction of travel. Targeting, communication and battery life would certainly have been an issue but one huge problem would have been that the probe would have to fly through the ejecta from the impact and probably not survive

[elakdawalla]

And of course what they really wanted to do with the flyby craft was watch the crater develop, which they couldn't have done from a much greater distance. Basically, they had predicted a length of time it would take for the "dust to clear," and multiplied that by some number to make their guess "conservative," and then they planned their sequencing. Tempel 1 sure fooled them. Too bad they couldn't see the crater develop with the camera, but they seem to have gotten lots of interesting data from the ejecta with the spectrometer.

--Emily

[tty]

Not necessarily diverted more, the probe would have simply reduced delta V in the direction of travel. Targeting, communication and battery life would certainly have been an issue but one huge problem would have been that the probe would have to fly through the ejecta from the impact and probably not survive

You can't just reduce speed in the direction of travel without changing your trajectory sideways too. I agree about the ejecta problem.

tty

[ljk4-1]

How porous/light would the comet have to have been for Deep Impact to have caused it to break apart?

[Comga]

Contact has been made with the Deep Impact fly-by spacecraft hibernating in solar orbit. No anomalies were reported. It is in good shape to do more science.
It will do a fly-by of Earth in about 23 months, which could be used to control its trajectory. Where it goes from there is yet to be decided.

[Guest_BruceMoomaw_*]

How porous/light would the comet have to have been for Deep Impact to have caused it to break apart?

No way that could ever have happened -- the impact was incapable even of measurably deflecting the comet's trajectory. Also keep in mind that, the softer a gravity-bound object like a comet or a "rubble pile" asteroid is, the HARDER it often is for an impact to break it apart -- the impact's energy is locally absorbed by simply throwing out some local ejecta, much of which then returns to the object through its gravity. It's like the difference between shooting at a brick and shooting at a sandbag. (Celestial objects that have actually been fragmented by a giant impact are though to often reassemble themselves this way, which indeed is what explains the existence of rubble piles -- and was once thought to be responsible for the jigsaw appearance of Miranda, although the favored theory on that has changed.)

[The Messenger]

No way that could ever have happened -- the impact was incapable even of measurably deflecting the comet's trajectory. Also keep in mind that, the softer a gravity-bound object like a comet or a "rubble pile" asteroid is, the HARDER it often is for an impact to break it apart -- the impact's energy is locally absorbed by simply throwing out some local ejecta, much of which then returns to the object through its gravity. It's like the difference between shooting at a brick and shooting at a sandbag...

This is one of the reasons I am vexed by the official interpretatations: Sandbags do absorb, but here we had 1) A brighter-than-expected UV pulse. 2) Greater-than-expected volume of ejecta in the opposite direction from the impact.

Can anyone draw me a map that shows how an object with 90% void volume could do that?

On a side note, I was meeting with Ball Aerospace on a different project last week, and they were quite defensive about the Deep Impact results. Ok - Bruce and I diss them about the lens issue, but don't we all agree Deep Impact was a tremendous engineering and scientific success? Isn't an unexpected result better than a mission that exactly matches a prior predictions?

[Guest_BruceMoomaw_*]

An new LPSC abstract on the subject by the Deep Impact science team ( http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2192.pdf ) says that the impact flash was a lot DIMMER than expected: "The overall luminous efficiency of the flash was far lower than predicted, most likely due to the high porosity and volatile content of the Tempel 1 surface." Extensive details are provided.

As for Deep Impact being "a tremendous engineering and scientific success": no quarrel about the former, but I have PLENTY of quarrels about the latter. When I look at the LPSC abstracts on the mission, I get the distinct impression that:

(1) Where science return is concerned, this thing delivered a lot less than they had hoped for, in regard to both the comet's physical structure and its chemical makeup;

(2) Most of the really useful stuff they got was from its images of the comet before the impact; and

(3) A simple CONTOUR-type mission -- perhaps with a subsurface radar sounder added -- would have produced a lot more.

From the moment this mission was picked (which apparently came as a major surprise to planetary scientists), I've always thought the selection had Captain Crazy written all over it, although admittedly I have no direct evidence of this. The resemblance to his abortive 2003 Mars Airplane just to commemorate the Wright Brothers centennial -- and to his cancellation of the Pluto mission because "Nobody gives a damn about Pluto" and astrobiology was SO much more spectacular -- is unmistakable. He was the Cecil B. DeMille of NASA, and this thing would have struck him as just the sort of Big Spectacle capable of attracting the rubes... er, voters.

[ljk4-1]

DEEP NEWS

Newsletter for the Deep Impact mission

Issue #30, January/February 2005

--------------------------------------------------------------------------------

It's amazing that in the world of space exploration, in which spacecraft
sometimes take years to reach a destination, the Deep Impact mission journeyed
through funding, design, building, launch, encounter, and this month - the
release of findings from the science team. With more study still to come, Deep
Impact was proven to be a tightly scheduled mission with spectacular results.
You joined us somewhere along the way getting our monthly updates and we hope
you enjoyed the ride. This issue is the last of our monthly updates and in the
future, we will contact you with shorter news about Deep Impact's science and
technology. If for some reason you are just joining us take a look at what you
have missed on our web sites:

http://deepimpact.jpl.nasa.gov

http://deepimpact.umd.edu


PICTURE THIS - WATER, WATER EVERYWHERE!

Well, perhaps not everywhere - but results from the IR spectrometer aboard the
Deep Impact flyby spacecraft show that water ice exists on only about 0.5% of
the comet's surface. Take a look and see where the team found the water ice.

http://deepimpact.jpl.nasa.gov/gallery/Sur...eLocations.html


MISSION UPDATE: NEW RESULTS FROM THE SCIENCE TEAM

Results from the flyby spacecraft's IR spectrometer are shared in a summary from
a paper by Co-Investigator Dr. Jessica Sunshine and the science team. Also, read
Ray Brown's outline of Deep Impact findings based on a summary of telescope
observations from Co-Investigator, Dr. Karen Meech and collaborators.

Summary from the Ground Observation:

http://deepimpact.jpl.nasa.gov/mission/upd...602.html#rbrown

Summary from the IR Spectrometer:

http://deepimpact.jpl.nasa.gov/mission/upd....html#lmcfadden


TECHNICAL UPDATE FROM THE PI - DR. MIKE A'HEARN AT THE UNIVERSITY OF MARYLAND

Principal Investigator Dr. Mike A'Hearn gives his science team a technical
update on the Deep Impact flyby spacecraft after the engineering group at Jet
Propulsion Laboratory communicated with it on February 10th.

http://deepimpact.jpl.nasa.gov/mission/upd...02.html#mahearn


UP CLOSE AND PERSONAL: MEET DR. KAREN MEECH, DEEP IMPACT CO-INVESTIGATOR

Karen knew since she was very young that she would end up working in astronomy
someday and there were lots of Star Trek episodes and evenings with her father
watching the sky to help confirm that decision. Meet Karen Meech.

http://deepimpact.jpl.nasa.gov/mission/bio-kmeech.html


FOR EDUCATORS: WHAT DOES THE MOON HAVE TO DO WITH THE DEEP IMPACT MISSION?

Well, quite a lot actually. Shortly after takeoff, the science team used the
spacecraft images of the moon to check the calibrations for their instruments.
Here is a Mission Challenge based on their calculations and set to national math
standards. Have your students do real mission math!

Question: What was the distance from the Deep Impact spacecraft to the moon on
January 16, 2005?

On January 16, 2005, the Deep Impact spacecraft turned its cameras back toward
Earth and captured some beautiful images of our Moon. To aid in calibrating the
spacecraft instruments, astronomers would like to know precisely how far Deep
Impact was from the moon when this picture was taken.

http://deepimpact.jpl.nasa.gov/disczone/ch...n_Distance.html


WAY TO GO, STARDUST! - RETURN TO SENDER

Congratulations to the Stardust Mission for the safe and successful return of
their capsule containing actual particles from comet Wild 2 on January 15, 2006.
There was great excitement as their science team viewed the grid in which
squares of aerogel safely cradled the first samples of cometary and interstellar
dust to be returned to Earth for study. As a sister to Deep Impact, findings
from both missions will bring scientists closer to answering questions about the
formation of the solar system.

http://stardust.jpl.nasa.gov/news/status/060125.html


PLANETARY SOCIETY ANNOUNCES THE WINNERS OF THE CRATER CONTEST

Although the precise dimensions of the crater made by the Deep Impact mission in
Tempel 1 were hidden by ejecta from its nucleus, the Planetary Society was able
to pick 3 winners from those whose predictions fell within the range determined
by the science team. Take a look.

http://www.planetary.org/about/press/relea...ry_Society.html


DID YOU SEE OUR PAST DEEP NEWS ISSUES?

Visit http://deepimpact.jpl.nasa.gov/newsletter/archive.html to catch up on
exciting past news from the Deep Impact mission.

Deep Impact is a Discovery mission. For more information on the Discovery
Program, visit:

http://discovery.nasa.gov/

The Deep Impact mission is a partnership among the University of Maryland (UMD),
the California Institute of Technology's Jet Propulsion Laboratory (JPL) and
Ball Aerospace and Technology Corp (BATC). Deep Impact is a NASA Discovery
mission, eighth in a series of low-cost, highly focused space science
investigations. See http://deepimpact.jpl.nasa.gov or our mirror site at
http://deepimpact.umd.edu.


SUBSCRIPTION INFORMATION:
Send this email along to your friends. If you received this newsletter from a
friend, you can contact us to subscribe here:

http://deepimpact.jpl.nasa.gov/feedback-form.html

The functions for searching for your certificate in the Send Your Name to a
Comet campaign and Signing Up for Deep News Newsletter were removed from the
site for our high web traffic time and will be returned in the future. Thanks
for your patience!


QUESTIONS ABOUT DEEP NEWS? CONTACT US AT:

http://deepimpact.jpl.nasa.gov/feedback-form.html

[The Messenger]

An new LPSC abstract on the subject by the Deep Impact science team ( http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2192.pdf ) says that the impact flash was a lot DIMMER than expected: "The overall luminous efficiency of the flash was far lower than predicted, most likely due to the high porosity and volatile content of the Tempel 1 surface." Extensive details are provided.

Thanks, Bruce - the earliest frames clearly indicate there was significant penetration before the impact flash, although the depth of the penetration is still up-in-th-air because of the oblique angle.

There are a lot of shudda whoulda couldda's surrounding this mission. I guess I am one of those yahoo's, because I would love to do it again.

[ljk4-1]

Article on Deep Impact in the latest The Planetary Society The Planetary Report:

Deep Impact: Understanding Comet Tempel 1

On July 4, 2005, the Deep Impact spacecraft sent a 370-kilogram (820-pound) copper ball on a collision course with comet Tempel 1 to give us our first look inside a comet. Within minutes of the impact, the spacecraft returned to Earth spectacular images of the explosive event. Exactly what these images and other data revealed, however, took much longer to analyze. Now, 6 months later, Deep Impact coinvestigator Lucy McFadden and coauthor Ray Brown detail what scientists are discovering about comet Tempel 1 and what Deep Impact has taught us about the oldest components of our solar system.

http://www.planetary.org/programs/planetary_report.html

[The Messenger]

Article on Deep Impact in the latest The Planetary Society The Planetary Report:


http://www.planetary.org/programs/planetary_report.html

The printed article is a little disappointing - There is an artist's rendition of the nucleus that makes it look like it has a heavy frosting of ice, and the caption calls it a 'dirty snow ball' 0.04% surface moisture is not consistent with either the rendition or description.