The NASA GRACE-FO (Gravity Recovery and Climate Experiment Follow-On mission) mission was launched on a SpaceX Falcon 9 rocket today (May 22) at 12:47 p.m. PDT (3:47 p.m. EDT) from Vandenberg's Space Launch Complex 4E. The GRACE-FO twin satellites will continue the work of the original GRACE mission in observing the movement of water and other mass around our planet by making very precise measurements of Earth’s gravitational field.
The Falcon 9 also carried another batch of five Iridium-6 communications satellites into Low Earth Orbit.
Landing and recovery of the first stage rocket were not attempted; this refurbished rocket was previously used in January for the ZUMA mission.
However, SpaceX did attempt to catch the fairings (at least one of them) using Mr. Steven, the fairing catcher. The fairing is the 2-piece nose cone that covers the payload cargo at the top of the rocket. Elon Musk — “We've got a special boat to catch the fairing... it's like a giant catcher's mitt in boat form." Previous attempts have been unsuccessful.
See diary “Meet Mr. Steven, the SpaceX Rocket Catcher” at www.dailykos.com/… for more info. on Mr. Steven.
Mr. Steven spotted by intrepid reporter Pauline Acalin -
The picture below shows the payload fairing, with the satellites encased inside it. The fairing consists of two eggshells, that separate out and fall back to Earth, guided by a parachute (a parafoil), while Mr. Steven maneuvers to catch it in its net. The fairing is worth $6 million and hence are worth recovering and reusing.
Here is a picture of the payload consisting of the twin GRACE-FO satellites on top and the five Iridium satellites at the bottom -
The GRACE-FO Mission
The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Center. It consisted of two satellites launched in March 2002; the mission ended in October 2017.
GRACE-FO is a follow on to the original mission, replacing the original satellites with two new more advanced versions. GRACE-FO will continue the work of tracking Earth's water movement to monitor changes in underground water storage, the amount of water in large lakes and rivers, soil moisture, ice sheets and glaciers, and sea level caused by the addition of water to the ocean. These discoveries provide a unique view of Earth's climate and have far-reaching benefits to society and the world's population.
The twin satellites will follow each other in orbit around the Earth, separated by about 220 km. They will constantly send (Ka-band) microwave signals to each other to measure the distance between them. Minor orbital perturbations caused by changes in the gravitational field will affect one satellite first, then the other, causing the distance between them to change minutely. Multiple measurements over many orbits will result in an accurate map of the changing gravitational field and will be used to map the movement of mass across Earth.
GRACE-FO also carries a Laser Ranging Inferometer (LRI), an experimental instrument that will use lasers to measure the distance between the two satellites with greater accuracy than microwaves.
GRACE-FO orbit: altitude = 490 km, period = 99 minutes, near circular sun-synchronous polar (89 degree inclination) orbit.
GRACE-FO is a joint project between NASA/JPL, CSR/UTexas, DLR German Aerospace Center, and GFZ Helmholtz Center Potsdam. There is significant participation and funding by the Germans.
GFZ provides Laser Retro-Reflectors for both satellites and funds the mission operations for 5 years. Mission operations will be conducted, as for GRACE, by GSOC (German Space Operation Center) of DLR in Oberpfaffenhofen.
The satellites were developed at Airbus Defence and Space in Friedrichshafen Germany.
See gracefo.jpl.nasa.gov and directory.eoportal.org/… for more info on GRACE-FO.
Updates
After a picture perfect launch, the GRACE-FO twins were successfully deployed, followed a bit later by deployment of the five Iridium-6 satellites. First signals from GRACE-FO were received at McMurdo station located in the Antarctic. This was SpaceX’s 10th flight this year. Congratulations to @SpaceX, @NASA and @IridiumComm.
After separation, the GRACE-FO satellites will re-orient themselves, so that their antenna side faces Earth; each satellites will be in slightly different orbit, to allow them to drift apart; once, they have achieve the desired 220 km separation, their orbits will be synchronized.
Mr. Steven unfortunately was not nimble enough to catch one of the fairings as it parachuted down from a height of 125 km; it ended up landing in the Pacific ocean. Both fairing pieces will be recovered and transported back.
The Iridium satellites reported healthy status as well -
Here is the full video of the launch and satellite deployment; there is a clip of Mr. Steven at the 3:50 mark.
Epilogue
In the midst of the miserable daily news emanating from the WH, and in spite of the worst efforts by the anti-science GOP (expect Rep. Mo Brooks to soon call for measurements of rocks falling into oceans), it is good to see that good science marches on.
Further Reading
- GRACE-FO (Gravity Recovery And Climate Experiment - Follow-On) / GFO (GRACE Follow-On) — directory.eoportal.org/…
- GRACE NASA — www.nasa.gov/...
- GRACE NASA JPL — grace.jpl.nasa.gov
- Gravity Recovery and Climate Experiment — en.wikipedia.org/…
- Meet Mr. Steven, the SpaceX Rocket Catcher — www.dailykos.com/...