On August 24 the MESSENGER assembly team rotated the spacecraft into a vertical position, attached hoist cables to an overhead crane, and lifted it just an inch or two off the Turnover Fixture for a few minutes. In the above image you can just make out a slight gap between the Turnover Fixture and the spacecraft. A time-lapse movie from that day (large or small versions) captures the full operation, as well as installation of the boom for MESSENGER’s Magnetometer instrument.

The crane also serves as a scale to give an accurate weight for the spacecraft. Controlling the weight of a spacecraft is one of the hardest challenges faced by any design and assembly team.

Every kilogram (or pound) is precious. Each kilogram MESSENGER weighs will require 233 kilograms of fuel on the launch vehicle to get the spacecraft on the path to Mercury. (A kilogram equals 2.2 pounds.)

On August 24 MESSENGER weighed in at 331 kilograms (without fuel, or "dry"), as expected at this stage of integration. MESSENGER’s estimated dry launch mass is 513 kilograms; once the spacecraft is fully fueled it will weigh 1,130 kilograms. For comparison, the three-stage Delta 2 launch vehicle set to send MESSENGER on its journey weighs 288,000 kilograms.

Last updated: September 4, 2003