The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) twin satellites launched May 22, 2018. The mission is a partnership between NASA and the German Research Centre for Geosciences (GFZ). GRACE-FO is a successor to the original GRACE mission, which operated from 2002 to 2017.
Like its predecessor, the two identical GRACE-FO satellites function as a single instrument. By tracking changes in their separation distance, the satellites are able to map regional gravity changes. A GPS system tracks each spacecraft’s position relative to Earth’s surface, and onboard accelerometers record forces on the spacecraft other than gravity, such as atmospheric drag and solar radiation. These data are combined to produce global monthly maps of the Earth’s gravity and corresponding surface mass variations, which primarily reflect changes in the distribution of water mass in Earth’s atmosphere, oceans, land and ice sheets. In addition, the experimental Laser Ranging Interferometer (LRI), designed to improve the precision of measuring the distance between the two spacecraft, is the first demonstration of laser interferometry between satellites. For more information about GRACE-FO, see: https://www.nasa.gov/gracefo and https://gracefo.jpl.nasa.gov/.
The GRACE mission launched March 17, 2002. After 2010, GRACE operation teams have overcome numerous technical challenges and developed innovative methods to work around the limitations imposed by aging batteries and limited fuel availability for flight control. The mission ended on October 12, 2017, when reduced satellite system power made useful dual satellite science data were no longer viable. Over 4,300 peerreviewed publications based on GRACE data appeared during the mission’s 15-year lifetime.
GRACE-FO continues the GRACE data record and its legacy of scientific achievements. GRACE & GRACE-FO chronicled the ongoing loss of mass in the Greenland and Antarctic ice sheets and mountain glaciers. That wealth of data shed light on the key processes, short-term variability and long-term trends that impact sea level rise, improving sea level projections. The estimates of total water storage on land derived from GRACE and GRACE-FO data, from groundwater changes in deep aquifers to changes in soil moisture and surface water, have provided tools to measure the impact of droughts and monitor and forecast floods. In addition, the data have been used to infer changes in deep ocean currents, a driving force in climate. GRACE data have also been used to measure changes within the solid Earth itself, such as the response of Earth’s crust to the retreat of glaciers after the last Ice Age, and the impact of large earthquakes.
This program element seeks proposals that will advance the development of new methods, algorithms, and models for the exploitation of gravity field observations made by GRACE, GRACE-FO, and future space-based gravity field missions for the broad spectrum of Earth system science challenges. It also seeks the development of techniques and algorithms capable of bridging gravity field observation across different gravity missions. Proposals are encouraged which are multidisciplinary in scope and which address the Earth System Science questions related to NASA's Strategic Goal 1 to "Expand Human Knowledge Through New Scientific Discoveries", Strategic Objective 1.1: “Understand the Earth system and its climate”. (See the most recent NASA Strategic Plan 2022: https://www.nasa.gov/sites/default/files/atoms/files/fy_22_strategic_plan.pdf. In particular, it addresses the more specific Science Goals, see SCIENCE 2020-2024: A Vision for Scientific Excellence (See A.1 The Earth Science Research Overview).
Deadlines:
- Notice of Intent: May 16, 2023
- Proposal: July 14, 2023