GRACE-FO mission, a collaboration between NASA and GFZ, was launched on 22 May 2018 aboard a SpaceX Falcon 9 rocket from Vandenberg AFB, California, sharing the launch with five Iridium NEXT satellites. During in-orbit checks, an anomaly was discovered in the primary system component of the microwave instrument (MWI), and the system was temporarily powered down on 19 July 2018. After a full investigation by an anomaly response team at JPL, the backup system in the MWI was powered up on 19 October 2018 and GRACE-FO resumed its in-orbit checks. GRACE-FO entered the science phase of its mission on 28 January 2019. The orbit and design of GRACE-FO is very similar to its predecessor. GRACE-FO employs the same two-way microwave-ranging link as GRACE, which will allow for similar inter-satellite ranging precision. In addition, GRACE-FO employs laser-ranging interferometry (LRI) as a technological experiment in preparation for future satellites. The LRI allows for more accurate inter-satellite ranging due to the shorter wavelength of light, and additionally allows the angle between the two spacecraft to be measured as well as their separation via differential wavefront sensing (DWS). Using the LRI, scientists have improved the precision of the separation distance measurements by a factor of more than 20 relative to the GRACE mission. Each laser on the LRI has about the same power as four laser pointers. These lasers must be detected by a spacecraft about away. This laser approach will generate much more accurate measurements than the previous GRACE satellite mission. The GRACE-FO satellites obtain electricity from gallium arsenide solar cell array panels covering the outside of each satellite. GRACE-FO will continue to monitor Earth's gravity and climate. The mission will track gravitational changes in global sea levels, glaciers, and ice sheets, as well as large lake and river water levels, and soil moisture. In addition, each of the satellites will use GPS antennas to create at least 200 profiles per day of atmospheric temperature distribution and water vapor content, a first for the GRACE mission. GRACE-FO has a design life of 5 years. See also Challenging Minisatellite Payload (CHAMP), an earlier single satellite mission using a similar "Flexbus" platform GRAIL, a similar NASA probe pair that mapped the Moon Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), an ESA gravity mapping mission that used only a single satellite References External links GRACE website by the University of Texas GRACE Tellus website by