STEREO Mission Design and Navigation Review Action Item 5
Closed, May 5, 2006
From: Guzman, Jose J. Sent: Tuesday, June 27, 2006 3:30 PM To: Strikwerda, Thomas Cc: Hunt, Jack; Dunham, David Subject: FW: FW: MDR AI #5 Tom, Here is the response with some additional comments from Jack and Brian on a sun glint issue that Roby brought up in his response. Jose -----Original Message----- From: Jack Hunt [mailto:jack.hunt@jhuapl.edu] Sent: Tuesday, May 09, 2006 9:49 AM To: Kantsiper, Brian Cc: Guzman, Jose J.; Ray, Courtney; Shapiro, Hongxing; Strikwerda, Thomas; Driesman, Andy; Cancro, George; Ossing, Daniel; Eichstedt, John Subject: Re: FW: MDR AI #5 Brian, Thanks for responding. I concur with Brian that while glint into the ST is a possibility, it should not be a problem for detumble. Jack Kantsiper, Brian wrote: > If the issue is during initial detumble, possible, but probably not. > The ST should be largely irrelevant for the detumble, as it relies > primarily on the IMU. The plan was to detumble on thrusters and then > slew on wheels to sun-pointing (i.e. I don't think ST has any > importance with the thrusters on), so likely the worst thing that > would happen is that ST would give a funky or no result, the ST/DSAD > comparison flag would trip, and the spacecraft would go to sun > pointing using DSAD. > If the question is about close approach later (~14 dy), I'd be very > surprised if there is a problem, but as long as we're not burning, > it's hard to see how it could hurt us much. I don't recall whether > there is an earth keepout for the ST, but, if not, I think specular > reflection off of the earth is a much likelier situation. Even if > there is an earth keepout, it's still probably more likely. > > No matter what, I don't see how this could do more than leave us safed > pointing off of DSAD & IMU. I'll defer to Courtney, Jack, and George, > though. > > -----Original Message----- > From: Guzman, Jose J. > Sent: Monday, May 08, 2006 5:27 PM > To: Hunt, Jack; Ray, Courtney; Shapiro, Hongxing; Kantsiper, Brian > Cc: Strikwerda, Thomas; Driesman, Andy; Cancro, George; Ossing, > Daniel; Eichstedt, John > Subject: FW: FW: MDR AI #5 > > We can close action item #5 from the mission design and navigation > review. > > I am curious about Roby's sun glint question. See his message below. > Could this be a problem? > > Jose > > -----Original Message----- > From: Guzman, Jose J. > Sent: Monday, May 08, 2006 5:22 PM > To: 'Roby Wilson' > Cc: Dunham, David; Sharer, Peter > Subject: RE: FW: MDR AI #5 > > Roby, > > Many thanks. > We recently had a flight operations review where the sequencing of > events was successfully presented from an operational perspective. > There have been other reviews where it has been presented as well. > I am not sure about the sun glint issue but now I am curious too. So, > I will ask... > > Jose > >> -----Original Message----- >> From: Roby Wilson [mailto:Roby.Wilson@jpl.nasa.gov] >> Sent: Friday, May 05, 2006 7:19 PM >> To: Guzman, Jose J. >> Cc: Roby Wilson; Dunham, David; Sharer, Peter >> Subject: Re: FW: MDR AI #5 >> >> Jose, >> >> Thanks for the update. I read through Peter's paper and it seems >> that >> alot of good analysis has gone into the separation sequence. I think >> that my original RFA was concerned primarily with the actual >> separation event itself. From response it appears that the cm/cg >> offset is not an issue. >> It is good to see that you have also examined the longer term >> propagation issues (Peter's work). I concur with your closure of the >> RFA. >> >> This part of the mission is perhaps the most harrowing and >> nerve-racking of anything that you do. Have you had a recent >> peer-review of the entire sequence from a systems engineering >> perspective? You might want to consider it, if you have the time and >> resources to do so. I am not sure what could be changed at this >> point, and it may be just to satisfy yourselves that you have not >> overlooked anything or to mitigate any risks that you do uncover. >> >> One other thought that I had while reading through this is whether or >> not there are any spoofing issues for the star-trackers from seeing >> the other spacecraft especially if you get some glint off of the >> solar >> arrays. It doesn't appear that you get any closer than 3 km or so >> after the initial separation (occurs at L+14 days). I am not sure if >> this is close enough to confuse a star-tracker (if you have them). I >> am curious to know if you have looked at this. >> >> Good luck with your launch campaign. I look forward to putting on my >> 3-D glasses to see your pictures of the Sun :) >> >> -Roby >> >> On Wed, May 03, 2006 at 06:56:57PM -0400, Guzman, Jose J. wrote: >> >>> Roby >>> >>> Attached is the proposed G&C response to the outstanding MD >> Review AI here. >> >>> #5. >>> Let us know if you concur. >>> You can get the referenced (Peter's paper) here. >>> >>> If you need the internal memo referenced in the response, >>> >> let us know. >> >>> We'll have to pipe that through the appropriate channels to >>> get it to you. >>> Many thanks, >>> >>> Jose >>> >> -- >> >> ------------------------------------------------------------------- >> Roby S. Wilson Jet Propulsion Laboratory >> Roby.Wilson@jpl.nasa.gov Section 343D -- M/S 301-125L >> Tel: (818) 393 5301 Fax: (818) 393 6388 >> ------------------------------------------------------------------- -- Jack Hunt (Email: Jack.Hunt@jhuapl.edu) The Johns Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Road, Laurel, MD 20723 Phone: 443-778-8615 (Baltimore) or 240-228-8615 (Washington) Fax: 443-778-0355