Broadcast 3089 Dr. Marc Rayman

26 Mar 2018 Dr. Marc Rayman
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Guest:  Dr. Marc Rayman;  Topics:  Updates with the Dawn Mission regarding Ceres.  Ceres changes coming, Ceres new extension of life and more.  Please direct all comments and questions regarding specific Space Show programs & guest(s) to the Space Show blog which is part of archived program on our website, www.thespaceshow.com.   Comments and questions should be relevant to the specific Space Show program. Written Transcripts of Space Show programs are a violation of our copyright and are not permitted without prior written consent, even if for your own use. We do not permit the commercial use of Space Show programs or any part thereof, nor do we permit editing, YouTube clips, or clips placed on other private channels & websites. Space Show programs can be quoted, but the quote must be cited or referenced using the proper citation format. Contact The Space Show for further information. In addition, please remember that your Amazon purchases can help support The Space Show/OGLF. See www.onegiantleapfoundation.org/amazon.htm.   

We welcomed Dr. Marc Rayman back to the show for this two segment 1 hour 59 minute discussion regarding the Dawn mission extension of life and Ceres updates.  We started our discussion talking about the Dawn Mission and the new NASA extension for the life of Dawn around the asteroid Ceres.  Our guest explained the options NASA had when the initial extension expired plus he told us why they decided to leave Dawn at Ceres to adjust the orbit to fly 22 miles above the asteroid to 2500 miles in a very stable orbit.  He explained the stable orbit and the end of life plans for Dawn which will happen later this year when it runs out of hydrazine.  Be sure to listen to this part of our first segment as is a super update on Dawn and what we have and are continuing to learn from Ceres. 

We talked for several minutes about the enhanced photography that would be possible when Dawn flies over Ceres at an altitude of 22 miles rather than the typical 250 miles.  Our guest talked about the camera, limitations that would still impact the photography and more.  One of the questions that Marc took changed the subject to how long it took to get Dawn to Ceres and would the new heavy lift launchers have gotten their faster.  Marc talked about why Dawn was launched on the Delta 2, the essential use of ion propulsion, and the launch vehicle mission trades that are considered with faster but more costly rockets, larger payloads, the need to carry more fuel and more.  Don't miss this discussion as it goes to the heart of mission planning for planetary missions. 

Another question focused on the bright spots on Ceres and if the lower orbit would tell us more about them.  Marc had much to say about the bright spots which were salt deposits (sodium carbonate).  Jack then sent in a question asking about the likelihood of getting to make another trip out to Ceres sometime in the future.  Marc talked about other missions that had repeats in them such as the many missions that flew by or went to Saturn.  He said Ceres may follow in those footsteps.  He also talked about setting planetary mission science objectives with the Decadal Survey.  As part of this mini-discussion, Marc was asked about possible future commercial planetary missions, that is could a company make money from a planetary mission such as Dawn.  Both Marc and I thought that the commercial opportunities were hard to see now but that may change in the future.  Marc did not rule it out and he did welcome it. 

Before the segment ended, BJohn sent in several emails. One asked our guest about the pros and cons of an asteroid flyby mission such as New Horizons as compared to an orbital mission such as Dawn.  Marc had much to say about the benefits of both missions.  Don't miss this discussion.  What type of mission do you prefer?  Let us know by posting on the blog.  Another of his emails asked our guest to comment on the upcoming Psyche and the Jovian Trojans missions.  The last question came from Phil asking about orbital perturbations for Dawn around Ceres.

We started the second segment with two unique questions.  Since I had just read the Celestis sponsorship message, a listener asked Marc for his opinion on a future space burial mission to Ceres to drop off ashes on the asteroid.  Don't miss what Marc said about this.  His answer may surprise you.  He also talked about the fact that Ceres was hard to get to and that is was about 10 degrees off the plain of Earth.  The second unique question was from Ben asked if for planetary missions in the future, were they to use nuclear thermal propulsion, could the planetary payloads be MERVED, meaning each launcher carry ten or so different planetary destination payloads since there would be more power with the nuclear thermal propulsion.  Don't miss what Marc said about this fairly far out question and idea.  In the process of responding to this question, Marc also addressed concerns about using nuclear thermal propulsion so again, don't miss this discussion. 

Phil sent in another question regarding Vesta and Ceres having 40% of the mass of the asteroid belt and navigation including the two body problem.  Marc addressed these issues in his response to Phil.  Marc then addressed water and water ice on Ceres and the fact that it did not appear to be stable as it increased during the time Dawn had been at Ceres.

Before the program ended, I asked Marc if there were surprises with Dawn that were not anticipated before launch day.  He talked about what they anticipated before launch and what they found at Ceres.  He cited several examples which you will find interesting.  A last minute question came in asking him for the date Dawn would run out of fuel and end.  Phil got in the final email suggesting the space navigators for Dawn and the comprehension of the celestial mechanics involved in such missions was maybe more amazing than the scientific objectives.

Please post your comments/questions on TSS blog.  You can reach Dr. Rayman though his JPL address and website or me.

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Dawn Mission & Ceres updates. See the Dawn Journal: www.jpl.nasa.gov/blog/2018/3/dear-vernal-dawnquinoxes

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