Emily LakdawallaFeb 14, 2011

Stardust flies by Tempel 1 in 5 hours, and I'll be watching!

Stardust is very close to the last major act of its mission: the flyby of Tempel 1, which will take place at 20:40 PST (04:40 UTC). Here's a summary of the recent and current status of the mission, and how to follow the events over the next 24 hours. But before that, here's Stardust's final optical navigation photo of the comet:

Tempel 1, 42 hours before Stardust's flyby
Tempel 1, 42 hours before Stardust's flyby This is the last optical navigation data taken by Stardust before its February 15, 2011 encounter with Tempel 1. It is a stack of five images of the comet. Mission scientists believe that they can detect the nucleus within these most recent images.Image: NASA / JPL / UMD

The current status was summarized in a press release from JPL and in several mission status updates.

  • The spacecraft is closing the distance to the comet at a rate of about 10.9 kilometers per second.
  • Since last Tuesday (February 8), the spacecraft has been acquiring 8 images of the comet every two hours, and is enjoying 24-hour-a-day DSN coverage, with at least one communications session per day taking place through a 70-meter antenna. Tuesday was also the first day they could sight the comet in single images, without needing to stack numerous images to pick the comet out of the noise.
  • On Friday, February 11 at 01:30 UTC, imaging was paused in order for the Navcam instrument to be heated to bake out the contamination that tends to accumulate on the instrument, fogging images.
  • As of later in the day Friday, February 11, the science team "believes that we are seeing the nucleus signal starting to come through."
  • A trajectory correction maneuver was performed on the evening of February 12.
  • Yesterday, Sunday, February 13, based on what they saw in that final set of navigation images, they decided not to execute the last possible trajectory correction maneuver. Their best guess is that they will travel within 191 kilometers of the comet, with a 11-kilometer uncertainty radius.
  • Today, at 21 hours before the flyby, the final encounter sequence was uplinked to the spacecraft:
    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. The encounter sequence is active. The encounter activity on board the spacecraft will begin at E-9 hours, when the Navcam CCD heater will be turned off to begin the final cooldown. This will be followed by setting the CIDA instrument to encounter mode at E-3 hours.  The telecom analysis for the predicted flyby attitude and locations shows that we will expect to support telemetry after the spacecraft turn to the final encounter attitude at E-1 hour. The supportable telemetry rate will be 504 bps. When the spacecraft executes the final roll for closest approach imaging at E-5 minutes, we may lose the signal, but it will return at E+5 minutes with the roll back. 

    The spacecraft is now fully configured for encounter and under autonomous control through the encounter.  Next planned commanding is after encounter, when the team will command the spacecraft to begin playback of stored telemetry followed by the images and dust data.
  • The contest to guess how far Stardust has traveled ends at 8:00 PST (04:00 UTC), so get your entries in!
  • You can use Eyes on the Solar System to see Stardust's current activity and position relative to the comet, and a simulated view from the navigational camera. I'll have that running on my computer as I watch the TV coverage!
  • Imaging of the comet nucleus will only begin four minutes prior to closest approach, and will last until four minutes after.
  • Beginning at 8:30 pm PST (04:30 UTC) there will be live coverage on NASA TV and JPL's UStream channel of nervous mission folks helplessly watching things transpire on monitors, and (hopefully) celebrating when they get telemetry back indicating that things went well. NASA TV coverage ceases at 10:00 pm PST (06:00 UTC). I'll be watching and tweeting.
  • Images should start arriving on the ground at about midnight local time (08:00 UTC). Each of the 72 images will take about 15 minutes to reach Earth; it'll take about 10 hours for all images and other data to be returned. NASA TV will broadcast live from JPL from midnight to 1:30 (08:00 to 09:30 UTC), and will hopefully show us images.
  • A post-flyby press briefing from JPL is planned for 10 a.m. tomorrow local time (18:00 UTC); I'll be at JPL for that and will probably Tweet from it. You'll be able to tune in via NASA TV and UStream.

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