Emily LakdawallaSep 26, 2007

Dawn launch: Go Dawn, go Delta!

Planetary Society volunteer Ken Kremer is reporting for us from the Kennedy Space Center, where he is anticipating the launch of Dawn on September 26. Kremer is a research scientist who spends his spare time giving public outreach presentations on behalf of The Planetary Society as a volunteer and NASA's Jet Propulsion Laboratory as a Solar System Ambassador. Thanks Ken! --ESL

"Dawn is fully configured for fight and armed for launch", according to Keyur Patel, the Dawn Project manager at JPL, with whom I spoke directly a short while ago at Kennedy Space Center. "All the dust covers have been removed. Everything is Go, weather permitting." A weather update is expected at 7 p.m. EDT. Keyur told me that he will give the final OK from JPL to launch during the manager's poll occurring at about 11 minutes prior to liftoff.

At the final pre-launch briefing at the Kennedy Space Center late this afternoon, Wednesday, September 26, the launch team stated "There are no issues and the team is ready!" This will be Launch #327 for a Delta rocket. The Delta II record is 75 for 75 since May 1997, which is the longest string of successful launches for any launch vehicle. Number 76 is expected on Thursday.

Mike Mook from Orbital Sciences Corporation (which built the Dawn spacecraft), stated that "All ordnance have been armed. At 4 p.m. today, the computers will be turned on and configured".

Scientific Principal Investigator Chris Russell from UCLA inspected the spacecraft at Pad 17-B on Tuesday evening and announced his approval for launch.

Here is a brief rundown on what to expect (all times EDT; add four hours for UTC, subtract three for PDT):Wednesday September 26
p.m. Weather briefing
0 p.m. Tower rollback at Launch Pad 17-BThursday September 27
:20 a.m. Terminal countdown begins at T-3 hours
t about T-80 minutes the liquid oxygen is loaded.
here are two built-in holds, temporarily halting the countdown, at T-15 minutes and T-4 minutes
-3 minutes Final approval for launch
:20 a.m. Launch window opens
+ 1 min 20 sec Jettison six ground-lit solid rocket motors
+ 2 min 39 sec Jettison three air-lit solid rocket motors
+ 4 min 41 sec jettison payload fairing
+ 1 hour 2 min spacecraft separation[For a more complete timeline you can consult the one I posted just before the previous launch opportunity in July, which has not changed very much with the new launch date. Marc Rayman describes the launch timeline thoroughly in this recent blog entry. --ESL]

After separation, the spacecraft will be slowly rotating. Automatic sequences will fire the small hydrazine rocket thrusters to stabilize the spacecraft. The solar arrays will be deployed over about 13 minutes when the spin is deemed safe. Only then will the low-gain antenna communications system be turned on to contact Earth. Acquisition of signal is not expected until about two to four hours after launch.

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