Questions for the LCROSS Scientists

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Oct 10, 2009, 8:58:31 PM10/10/09
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Although the newsgroup is in close-down mode, I wanted to leave one
more question for the LCROSS team. Are there any early results from
the follow-up ground-based OH lunar exosphere monitoring? Are
elevated levels of OH being detected above the dark limb near the
site? Good job. Best wishes. Thanks for an entertaining and
educational experiment. - Kurt

Oct 10, 2009, 9:56:08 PM10/10/09

I've been a lurker - but, this question strikes to the heart of what HST had hoped to observe.

We saw no OH- nor CO Cameron bands ... nothing. The STIS pre-impact data (this was our calibration orbit) and the post-impact data show no obvious exosphere. The data requires further analysis, but nothing was obvious.

Another follow-up STIS observation executed today (and, I'd expect the same result).

Rob Landis

Sent from my Verizon Wireless BlackBerry


Oct 11, 2009, 1:00:22 AM10/11/09
to LCROSS_Observation
Thanks for the preliminary results update, Rob. So, no indication of
a developing OH exosphere from Hubble. For other lurkers, I
understand Rob is associated with the Hubble Space Telescope’s
Education and Public Outreach Office. Clear Skies - Kurt
> educational experiment. - Kurt- Hide quoted text -
> - Show quoted text -

Tom Munnecke

Oct 11, 2009, 1:12:01 AM10/11/09
re: "Although the newsgroup is in close-down mode"  why does this have to close down, just when the analysis is beginning?  seems like a good place to connect with what's happening...

Oct 11, 2009, 1:03:37 PM10/11/09

Actually, in the interest of full(er) disclosure - I was at STScI from 1992-97. Worked in the technical end (helping astronomers who had been awarded time on HST with their programs) and did a short stint in the public outreach group.

Skipping to the present, I now work for NASA (Ames Research Ctr) and on extended TDY to JSC in the Lunar Surface Systems Project. A small group of us got DD time on HST for the impact event.

The HST data is (or shortly will be) in the public archive. For reference, this was HST program 11806. There might be some hint of something in yesterday's STIS data -- but I tend to doubt it. Alex Storrs is science point-of-contact for the HST work.

While I'm disappointed we didn't see something more spectacular - this is how science works. I also think some of this was overhyped. (For P/SL-9, we deliberately under-'hyped' it as we didn't know what we might see...but, were prepared for event. As everyone here knows - SL-9 was incredibly exciting as events unfolded at Jupiter.)

Hope this helps give context as to what HST observed. Data is not at all photogenic as we went after the science - in search of OH in the exosphere.

Tom Munnecke

Oct 11, 2009, 3:59:40 PM10/11/09
Thanks for the link to Palomar... I noticed a slight shift in the perspective during the Palomar video, which I presume is the moon's libation (slide the video's frame timeline quickly from left to right and you can see the moon rotate). 

I thought it might show some interesting depth to it, so I extracted the first and last image of the sequence as a stereo pair.  I've posted it on my blog at and a Rick has uploaded a separate PDF - its called Stereo image of Cabeus from Palomar.pdf

(I also did a similar trick to do a stereo image of a black hole,

I'm just wondering if anyone else sees a stereo effect with this?  I've spent so much time staring at this section of the moon recently, its hard to know what's what any more.


Oct 12, 2009, 8:26:55 PM10/12/09
to LCROSS_Observation
On Oct 10, 6:58 pm, "" <> wrote:

One last parting question for the LCROSS scientists before I sign off

I would like to roughly estimate the height of the actual plume using
three graphs displayed at the LCROSS post-impact press conference.

What is are the equivalent time units in seconds for the Data Handling
Unit (DHU) timestamp displayed in three graphs at the LCROSS post-
impact press conference of 10-9-2009?

At minute-seconds 10:42, 11:43 and 11:52 of the press conference
video, three radiance graphs are displayed.

From the graphs, it appears the plume was first detected by
shepherding spacecraft at 0.0003 to 0.0005 DHU time units before

Assuming the actual impact occured at the pre - event published values
of 2.5 km /s and an angle of about 65 degrees, if the absolute value
of DHU timestamp units is known, then the height of the plume can be
estimated. In t seconds the LCROSS shepherding satellite would
travel t secs, a distance (d) of t secs x 2500 meters / sec. With
respect to a normal surface, that distance represents the hypotenuse
of a right - triangle, the height of which is sin (65 degrees) x d.
If the absolute time units of the DHU timestamp can be determined in
second units, then an estimate of the height of the LCROSS plume in
meters could be made using -

h meters = Sin[ 65 Degree] * 2500 meters/sec * t secs

h = 2265.77 x t

Ditto to JHJ comment - great outreach program.

Clear Skies - Kurt

LCROSS Post-Impact Press Conference archvied on YouTube


Oct 13, 2009, 12:27:05 AM10/13/09
to LCROSS_Observation
On Oct 12, 6:26 pm, canopus56 <> wrote:

To correct

> From the graphs, it appears the plume was first detected by
> shepherding spacecraft at 0.0003 to 0.0005 DHU time units before
> impact.

Should read

From the graphs, it appears the plume was first detected by
shepherding spacecraft at 0.0003 x 10^6 to 0.0005 x 10^6
DHU time units before impact, i.e. - 30 to 50 DHU time units
before impact.

Clear Skies - Kurt

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