Stardust-NExT, Revisiting Tempel 1 Options

[Paolo]

I thought it was time to start a new thread on Stardust's flyby of Tempel 1, the first time a comet receives a second visit from a spacecraft one perihelion later.
There was an interesting story about this on Spaceflight now recently http://www.spaceflightnow.com/news/n1012/23stardustnext/
note that the flyby will be around 23.30 eastern time on 14 February, so thinking in GMT it will not happen on Valentine's day.
Stardust should have started imaging Tempel 1 twice weekly in mid-December, but there is nothing yet on the mission site http://stardustnext.jpl.nasa.gov/index.html
see also http://stardustnext.jpl.nasa.gov/mission/m...tatus10_q4.html for updates on the mission status

[stevesliva]

I don't know if these updates all came in at once, or if changes in the page format fooled feedity:
http://stardustnext.jpl.nasa.gov/mission/m...tatus11_q1.html

Some excerpts.

Frday, Feb 11. E- 3days
The opnavs received today are all at 0.25 pixel quality, and have moved the solution since yesterday’s opnav solution. The science team believes that we are seeing the nucleus signal starting to come through, and these latest opnavs are the best indication of the nucleus location. The maneuver design is being finalized, and will be around a 170 km maneuver.

Sunday Feb 13, E-1 day
The overnight activities taken by the flight team went very well, and the final OpNavs taken at E-42 hours were successfully acquired and downlinked.
The navigation solutions were finished this morning, and they show that the predicted delivery is within the ‘green zone’ of the delivery chart. The nominal flyby point is at 191 km from the surface of the comet with a 11km uncertainty radius. The current Time of Closest Approach estimate is still around 04:40 UTC on February 15 (20:40 February 14 in Pasadena). Based on these discussions and updates, the following decisions were made, with full concurrence between the PM and PI:
- No TCM 34 will be executed

Monday Feb 14, E-21 Hours
The spacecraft team has just completed the final commanding prior to encounter.
This included the encounter sequence and the supporting files that were built this afternoon with the final trajectory and time of arrival estimates.
Most fault protection has now been disabled, and the Mission Phase Bit has been set to ‘Encounter’. From now on, a safe mode entry will trigger the autorecovery sequence that will attempt to recover the spacecraft autonomously and restart the encounter sequence

Crazy! But after the worry, optical navigation got them where they wanted, with a TCM to spare.