The mass properties of the BepiColombo Mercury Transfer Module Structural and Thermal Model have been measured. The transfer module's primary task is to provide solar-electric propulsion during the mission's journey to Mercury.

The mass properties (total mass, centre of gravity (CoG) and moment of inertia (MoI) about all three axes) of the BepiColombo Mercury Transfer Module (MTM), the component of the composite spacecraft that will provide solar-electric propulsion for the journey to Mercury, have been measured at ESA's European Space Research and Technology Centre (ESTEC) in Noordwijk, the Netherlands.

The mass properties of the MTM were measured using similar techniques to those that were employed for the Mercury Planetary Orbiter (MPO) and the Mercury Composite Spacecraft (MCS). (See journal entries #06 and #07 for further details.)

MTM testing
The tests were again performed in the 'Hydra' cleanroom at the ESTEC Test Centre; the MTM assembly was installed on the WM50/6 test system for lateral CoG measurements, and on the M80/MPMA test system for longitudinal CoG and MoIs determination.

The WM50/6 was used to measure the position of the spacecraft CoG along the lateral (horizontal, in this configuration) axes. The M80/MPMA was used to determine the position of the spacecraft CoG along its longitudinal axis and the Products of Inertia (PoI) about all axes.

BepiColombo is Europe's first mission to Mercury. It is scheduled to launch in August 2015 and arrive at Mercury in January 2022.

It will endure temperatures in excess of 350C and gather data during a one-year nominal mission, with a possible one-year extension. The mission comprises two spacecraft: the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO).

During the journey to Mercury, the MMO will be shielded from the Sun by the Magnetospheric Orbiter Sunshield and Interface Structure (MOSIF), which also provides the interface between the MMO and the MPO.

The fourth component of the composite spacecraft stack is the Mercury Transfer Module (MTM), whose primary task is to provide solar-electric propulsion for the journey to Mercury.