Space and astronomy news and information for the American Southwest. Coverage includes Vandenberg AFB rocket and missile launches.

MESSENGER Viewing Opportunity

Brian Webb

2004 July 31

Preparations are under way at Cape Canaveral Air Force Station for the launch of NASA's MESSENGER spacecraft to the planet Mercury. A Delta II booster carrying the probe is scheduled to lift-off on August 1 at 23:16:11 PDT (August 2 at 06:16:11 UTC), the start of a 12-second launch window.

MESSENGER team member and amateur astronomer David Dunham reports that the spacecraft should be bright enough to see with optical assistance immediately after the Delta II's third stage fires and sends the craft on its way to Mercury.

"The injection into its heliocentric orbit, performed with the Delta rocket 3rd stage, will be in daylight N.W. of Australia, but the spacecraft will then climb rapidly in height and head towards Hawaii. It will raise almost straight up over Hawaii, and then the Earth's rotation will catch up, moving the ground track west from there, over Japan, Asia, Europe, etc., gaining height and becoming fainter. But while over Hawaii, it will be relatively close in a dark sky, well placed for optical observation from Hawaii and western North America ... I think it will be 7th or 8th mag. at this part of the trajectory, around 8h UT of August 2 (the geometry will be similar, with similar timing, for the other launch dates). It will be rather fainter as it rises for other locations, but maybe still 9th or 10th mag., for Japan and Asia, maybe 11th mag. for Europe."

Dunham said that observers can find out where to look for MESSENGER from their location using JPL's Horizons web site at

He added "You should start the calculations at 7:10 UT of Aug. 2; any earlier and you will get an error message because the spacecraft trajectory file starts shortly after the expected separation from the spent 3rd stage rocket (you might see it, too, nearby) sometime during 7:09 UT. You can check the options that suppress output when the Sun is above the horizon and the spacecraft is below it." Select MESSENGER as the Target Body.

For MESSENGER countdown and launch status, go to:

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