Starting in 2008 GFZ has initiated three R&D studies together with SpaceTech GmbH (STI). The first was called “GRAF” (GRACE Follow-on, August 2008 – March 2009) and was focusing on a mission with improvements in terms of accuracy and resolution based on lessons learnt from GRACE and domestic technology. As one of the outcomes of the GRAF study was that a microwave (MW) link with sufficient accuracy is not available in Germany, the second study “3M4C” (Mass Motion Monitoring for Climate, May 2009 – August 2009) investigated the substitution of the MW link by a Laser Doppler Interferometer (LDI) as well as alternative orbit scenarios, in particular a pendulum orbit at lower altitude. The third study “3M4C-FPS” (3M4C Fine Pointing Study, January 2010 – September 2010) investigated the various options for the LDI pointing (spacecraft or instrument pointing) which has much higher requirements than a MW SST link.

Project Partners:

• Space Tech GmbH, Immenstaad, Germany

Project Duration:

• 01/2008-12/2010

Funding:

• GFZ