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gpurcell
Posted on: Feb 26 2015, 07:28 PM


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Poking around this old thread led me to Dr. Brown's blog and from there to the information that he is teaching a free Coursera online course March 30th through June 9th called "The Science of the Solar System."
  Forum: Pluto / KBO · Post Preview: #218395 · Replies: 33 · Views: 112227

gpurcell
Posted on: Nov 15 2014, 01:25 AM


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Major congratulations to everyone involved! Great job of improvising in a very difficult situation and thanks for inviting us along for the ride.
  Forum: Rosetta · Post Preview: #215315 · Replies: 1412 · Views: 1230793

gpurcell
Posted on: May 30 2014, 01:31 AM


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Is receiving telemetry the same as getting transponding?
  Forum: Cometary and Asteroid Missions · Post Preview: #209994 · Replies: 91 · Views: 140044

gpurcell
Posted on: Sep 28 2012, 07:28 PM


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Done. Best money I've spent in awhile.
  Forum: Forum News · Post Preview: #192333 · Replies: 59 · Views: 144274

gpurcell
Posted on: Sep 8 2012, 06:12 AM


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My take switching into LAB space:
  Forum: MSL · Post Preview: #190910 · Replies: 252 · Views: 429883

gpurcell
Posted on: Aug 20 2012, 09:34 PM


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QUOTE (Drkskywxlt @ Aug 20 2012, 04:25 PM) *
Hmm...sounds like confidence in cost estimates was a key factor in Insight's selection. Insight came in a bit below the cap.


Yep. No more DAWNs.
  Forum: Exploration Strategy · Post Preview: #189251 · Replies: 56 · Views: 63938

gpurcell
Posted on: Aug 20 2012, 08:04 PM


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I think it is pretty tough to argue with this selection. It's an instrument package that we've needed to send for a long time and it's got a well-defined risk profile.

Additional Thoughts:
I think this is a really important mission. Between it and Curiosity, we'll really be at an inflection point in Mars exploration strategy by 2018/20 or so, with prety good data confirming one of four big picture views of the planet:

1) Wet Mars and live internal heat/movement;
2) Wet Mars and no current internal heat/movement;
3) Dry Mars and live internal heat/movement; and
4) Dry Mars and no current internal heat/movement.

The relative value of a major effort like MSR compared to other solar system exploration priorities really depends on which of these four broad stroke pictures ends up being closest to the truth.
  Forum: Exploration Strategy · Post Preview: #189240 · Replies: 56 · Views: 63938

gpurcell
Posted on: Aug 14 2012, 08:46 PM


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Given the budget constraints of the Mars Exploration Program in the next couple of launch opportunities, I wonder if it would make more sense to transfer the existing funds to Discovery and fund InSIGHT and one of the others for Discovery 12. It would be nice to get back to two missions per announcement.
  Forum: Exploration Strategy · Post Preview: #188592 · Replies: 56 · Views: 63938

gpurcell
Posted on: Aug 9 2012, 12:32 PM


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QUOTE (dvandorn @ Aug 8 2012, 10:30 PM) *
And on an historical note, how many of us who sat around our television sets watching the CBS News live coverage of the close approach of Mariner 7 as it flew by Mars, on August 5, 1969, guessed that 43 years and a day later we'd be watching Curiosity being lowered gently to the ground on a rope?


I vaguely remember the front page of the newspaper when one of the Vikings landed. For me "Mars" really began watching a bunch of "kids" my age (in very un-NASA like attire) in what looked like a spare conference room at JPL waiting to see if a spacecraft in a bouncing ball would work. How did they ever get old? smile.gif

What's amazing to me is that we've gone from thinking how cool it would be to get a closer look at "Twin Peaks" to getting ready to climb a mountain with a freaking nuclear-powered rover in 15 years! That's faster than I would have ever imagined back in 1997.
  Forum: MSL · Post Preview: #187916 · Replies: 1152 · Views: 962148

gpurcell
Posted on: Aug 8 2012, 03:24 PM


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Given the extremely thin atmosphere on Mars I doubt that wind pressure could overcome (or even seriously diminish) whatever force vector the parachute centroid had following the impact of the backshell.
  Forum: MSL · Post Preview: #187717 · Replies: 199 · Views: 178788

gpurcell
Posted on: Aug 8 2012, 01:28 PM


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What struck me most in Iceland most were the glaciation deposits and stream runoff structures but I guess the rubble fields DO look a lot like the rubble fields at Gusev and Ares Vallis. The color difference is disconcerting though--Iceland for me is a shadowy place of blues and white (I was there in winter).
  Forum: MSL · Post Preview: #187679 · Replies: 1152 · Views: 962148

gpurcell
Posted on: Aug 8 2012, 01:13 PM


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By far the most Earth-like terrain any lander has encountered. Looks a lot like desert pavement in Namibia.
  Forum: MSL · Post Preview: #187673 · Replies: 1152 · Views: 962148

gpurcell
Posted on: Aug 8 2012, 12:04 AM


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QUOTE (NickF @ Aug 7 2012, 05:56 PM) *
Are those three dark splodges in the crater NW of the SkyCrane impact site likely to be pieces thereof?


That's my interpretation. There's actually a smaller object with four bounces south of there as well:


  Forum: MSL · Post Preview: #187554 · Replies: 199 · Views: 178788

gpurcell
Posted on: Aug 7 2012, 05:31 PM


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Looks like a major component hit, bounced twice, and then finally impacted against that small rise.
  Forum: MSL · Post Preview: #187442 · Replies: 1152 · Views: 962148

gpurcell
Posted on: Aug 7 2012, 05:20 PM


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Love that oblique impact from the skycrane. Looks like a single piece skidded a fair way further than the rest of the vehicle; maybe the hydrazine tank?
  Forum: MSL · Post Preview: #187435 · Replies: 1152 · Views: 962148

gpurcell
Posted on: Aug 6 2012, 12:43 PM


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I'm very happy at the first look at the ground; whatever else Gale is like, it isn't like Gusev!
  Forum: MSL · Post Preview: #187012 · Replies: 1152 · Views: 962148

gpurcell
Posted on: Aug 6 2012, 05:59 AM


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Rob, felt a lot more controlled than Pathfinder or the MERs.
  Forum: MSL · Post Preview: #186859 · Replies: 1152 · Views: 962148

gpurcell
Posted on: Aug 6 2012, 05:40 AM


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I love seeing that shadowed silhouette of MSL.
  Forum: MSL · Post Preview: #186831 · Replies: 191 · Views: 90973

gpurcell
Posted on: Aug 6 2012, 05:14 AM


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No kidding, Phil. The visualization is astonishing even compared to MER (let alone Pathfinder when I actually drove out to Tidbinbilla to see the feed)
  Forum: MSL · Post Preview: #186761 · Replies: 191 · Views: 90973

gpurcell
Posted on: Aug 5 2012, 06:42 AM


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Redstone, thanks for that link. I wonder if that over 10 percent failure probability is why JPL isn't too keen to use any more bouncing ball landings on Mars....
  Forum: MSL · Post Preview: #186598 · Replies: 191 · Views: 90973

gpurcell
Posted on: Jul 23 2011, 03:38 AM


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What I really love about this site is the vertical relief and huge stratigraphic column that the rover will traverse, particularly since the landing ellipse is in the deepest trough of the crater. As awesome as Oppy's mission has been our ability to peer deeply into the past there is limited.

Gale will be the grandest Mars mission of our lifetime. I am so excited about this.
  Forum: MSL · Post Preview: #176042 · Replies: 365 · Views: 228342

gpurcell
Posted on: Jul 18 2011, 10:41 PM


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Circle your calendars for Friday at 10 AM EDT--landing site will be announced then.

http://www.spaceref.com/news/viewpr.html?pid=34138
  Forum: MSL · Post Preview: #175728 · Replies: 365 · Views: 228342

gpurcell
Posted on: Jun 17 2009, 06:51 PM


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What does a 2018 launch opportunity provide that a 2020 launch wouldn't? In other words, are there technical reasons beyond the obvious 2 year gap to prefer one versus the other?
  Forum: Jupiter · Post Preview: #142035 · Replies: 97 · Views: 132471

gpurcell
Posted on: Jun 17 2009, 01:03 PM


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Interesting language in the House markup:

QUOTE
The Committee is concerned that the budget profile for the Outer Planets flagship mission to Europa appears inconsistent with a 2020 launch. Therefore, NASA is directed within 60 days of enactment of this Act to provide a projected full lifetime budget outline for the Europa mission, to include anticipated contributions from foreign partners, and an alternative budget profile that would accelerate the launch to 2018.
  Forum: Jupiter · Post Preview: #142012 · Replies: 97 · Views: 132471

gpurcell
Posted on: Jun 4 2009, 05:19 PM


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QUOTE (Nomadd22 @ Jun 3 2009, 08:24 PM) *
Don't forget to budget for some really long extension cords. There's no more Plutonium 238 available for RTGs.


They are restarting production, finally:
http://www.msnbc.msn.com/id/30621668/

  Forum: MSL · Post Preview: #141421 · Replies: 177 · Views: 205340

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