Editing GRACE and GRACE-FO (section)

{{short description|Joint American-German space mission to map Earth's gravitational field}}
{{Infobox spaceflight |auto=all
| name                  = GRACE
| names_list            = GRACE-1 and GRACE-2<ref name="NSSDCA G1">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2002-012A |title=GRACE 1 |work=[[National Space Science Data Center]] |publisher=NASA |access-date=17 August 2016}}</ref><ref name="NSSDCA G2">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2002-012B |title=GRACE 2 |work=[[National Space Science Data Center]] |publisher=NASA |access-date=17 August 2016}}</ref> <br/> Tom and Jerry<ref name="NSSDCA G1" /><ref name="NSSDCA G2" /> <br /> ESSP-2A and ESSP-2B<ref name="gunters">{{cite web |url=http://space.skyrocket.de/doc_sdat/grace.htm |title=GRACE (ESSP 2) |work=Gunter's Space Page |access-date=10 December 2017}}</ref>
| image                 = GRACE spacecraft model 2.png
| image_size            = 275px
| image_caption         = Illustration of the twin GRACE satellites

| mission_type          = Gravitational science
| operator              = [[NASA]]{{·}}[[German Aerospace Center|DLR]]
| COSPAR_ID             = {{unbulleted list|2002-012A|2002-012B}}
| SATCAT                = 27391 and 27392
| website               = {{URL|http://www.csr.utexas.edu/grace}}
| mission_duration      = Planned: 5 years <br /> Final: {{time interval|17 March 2002 09:21|27 October 2017|show=ymd|sep=,}}

| spacecraft_bus        = Flexbus<ref name="gunters" />
| manufacturer          = [[Astrium]]
| launch_mass           = {{convert|487|kg|lb|abbr=on}} each<ref name="presskit-launch">{{cite web |url=https://www.jpl.nasa.gov/news/press_kits/gracelaunch.pdf |title=GRACE Launch: Press Kit |publisher=NASA |date=March 2002 |access-date=11 December 2017}}</ref>
| dry_mass              = 
| dimensions            = {{convert|1.942|xx|3.123|xx|0.72|m|ft|1|abbr=on}}<ref name="presskit-launch" />
| power                 = <!--end-of-life power, in watts-->

| launch_date           = {{start-date|17 March 2002, 09:21}}&nbsp;UTC<ref name="nssdc-orbit" />
| launch_rocket         = [[Rokot|Rokot-KM]] #2<ref name="gunters" />
| launch_site           = [[Plesetsk Cosmodrome|Plesetsk]] [[Plesetsk Cosmodrome Site 133|LC-133/3]]<ref name="gunters" />
| launch_contractor     = [[Eurockot Launch Services|Eurockot]]
| entered_service       =

| declared              = {{end-date|27 October 2017}}<ref name="end-of-science-mission"/>
| decay_date            = {{nowrap|GRACE-1: 10 March 2018,<br />{{in5}}06:09&nbsp;UTC<ref name="decay-1">{{cite web |url=https://www.space-track.org/basicspacedata/query/class/tip/NORAD_CAT_ID/27391/orderby/ID%20DESC/format/html/ |title=Decay Data: GRACE-1 |publisher=Space-Track |date=10 March 2018 |access-date=11 March 2018 |url-access=registration}}</ref>}} <br /> {{in5}}{{coord|-45.9|20.4}} <br /> {{nowrap|GRACE-2: 24 December 2017,<br />{{in5}}00:16&nbsp;UTC<ref name="decay-2">{{cite web |url=https://www.space-track.org/basicspacedata/query/class/tip/NORAD_CAT_ID/27392/orderby/ID%20DESC/format/html/ |title=Decay Data: GRACE-2 |publisher=Space-Track |date=24 December 2017 |access-date=13 February 2018 |url-access=registration}}</ref>}} <br /> {{in5}}{{coord|63.9|-160.9}}

| orbit_reference       = [[Geocentric orbit|Geocentric]]
| orbit_regime          = 
| orbit_semimajor       = {{convert|6873.5|km|abbr=on}}
| orbit_eccentricity    = 0.00182
| orbit_periapsis       = {{convert|483|km|mi|abbr=on}}
| orbit_apoapsis        = {{convert|508|km|mi|abbr=on}}
| orbit_inclination     = 89.0°
| orbit_period          = 94.5 minutes
| orbit_epoch           = 17 March 2002, 04:21&nbsp;[[UTC]]<ref name="nssdc-orbit">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=2002-012A |title=Trajectory Details: GRACE 1 |work=[[National Space Science Data Center]] |publisher=NASA |access-date=23 May 2019}}</ref>
| apsis                 = gee

| instruments           = <!--a list of instruments on the satellite-->
}}

The '''Gravity Recovery and Climate Experiment''' ('''GRACE''') was a joint mission of [[NASA]] and the [[German Aerospace Center]] (DLR). Twin satellites took detailed measurements of [[Earth's gravity]] [[Gravitational field|field]] [[gravity anomaly|anomalies]] from its launch in March 2002 to the end of its science mission in October 2017. The two satellites were sometimes called Tom and Jerry, a nod to the [[Tom and Jerry|famous cartoon]]. The '''GRACE Follow-On''' ('''GRACE-FO''') is a continuation of the mission on near-identical hardware, launched in May 2018. On March 19, 2024, NASA announced that the successor to GRACE-FO would be Gravity Recovery and Climate Experiment-Continuity ('''GRACE-C'''), to be launched in or after 2028.<ref>{{Cite web |last= |date=March 19, 2024 |title=US, Germany Partnering on Mission to Track Earth’s Water Movement |url=https://www.jpl.nasa.gov/news/us-germany-partnering-on-mission-to-track-earths-water-movement |access-date=2024-03-21 |website=NASA Jet Propulsion Laboratory (JPL) |language=}}</ref>

By measuring [[gravity]] anomalies, GRACE showed how mass is distributed around the planet and how it varies over time. Data from the GRACE satellites is an important tool for studying Earth's [[ocean]], [[geology]], and [[climate]]. GRACE was a collaborative endeavor involving the Center for Space Research at the [[University of Texas at Austin]], NASA's [[Jet Propulsion Laboratory]], the German Aerospace Center and [[GFZ German Research Centre for Geosciences|Germany's National Research Center for Geosciences]], Potsdam.<ref>{{cite web |url=http://www.jpl.nasa.gov/news/news.cfm?release=2002-0174 |title=Grace Space Twins Set to Team Up to Track Earth's Water and Gravity |publisher=NASA/JPL |access-date=14 August 2009 |archive-date=5 June 2011 |archive-url=https://web.archive.org/web/20110605041318/http://www.jpl.nasa.gov/news/news.cfm?release=2002-0174 |url-status=dead }}</ref> The Jet Propulsion Laboratory was responsible for the overall mission management under the NASA ESSP (Earth System Science Pathfinder) program.

The principal investigator is Byron Tapley of the [[University of Texas]] Center for Space Research, and the co-principal investigator is Christoph Reigber of the [[GFZ German Research Centre for Geosciences|GeoForschungsZentrum (GFZ) Potsdam]].<ref name="overview">{{cite web |url=http://www.csr.utexas.edu/grace/overview.html |title=Mission Overview |publisher=University of Texas |date=19 November 2008 |archive-url=https://web.archive.org/web/20090515114041/http://www.csr.utexas.edu/grace/overview.html |archive-date=15 May 2009 |url-status=dead}}</ref>

The two GRACE satellites, GRACE-1 and GRACE-2, were launched from [[Plesetsk Cosmodrome]], Russia, on a [[Rockot]] ([[SS-19]] + [[Briz (rocket stage)|Briz]] upper stage) launch vehicle on 17 March 2002.  The spacecraft were launched to an initial altitude of approximately 500&nbsp;km at a near-polar inclination of 89°.  During normal operations, the satellites were separated by 220&nbsp;km along their orbit track. This system was able to gather global coverage every 30 days.<ref>{{cite web |url=https://earthobservatory.nasa.gov/Features/GRACE/page3.php |title=Gravity Anomaly Maps and The Geoid |work=Earth Observatory |publisher=NASA |access-date=14 March 2018 |date=30 March 2004}}</ref> GRACE far exceeded its 5-year design lifespan, operating for 15 years until the decommissioning of GRACE-2 on 27 October 2017.<ref name="end-of-science-mission">{{cite web |url=https://www.jpl.nasa.gov/news/news.php?feature=6984 |title=Prolific Earth Gravity Satellites End Science Mission |last=NASA |website=[[Jet Propulsion Laboratory]] |date=27 October 2017 |access-date=31 October 2017}}</ref> Its successor, [[#GRACE_Follow-On|GRACE-FO]], was successfully launched on 22 May 2018.

In 2019, a [[glacier]] in [[West Antarctica]] was named after the GRACE mission.<ref name="bbc20190607">{{cite news |url=https://www.bbc.com/news/science-environment-48547803 |title=Antarctic glaciers to honour 'satellite heroes' |work=BBC News |first=Jonathan |last=Amos |date=7 June 2019 |access-date=29 September 2019}}</ref><ref name="esa20190607">{{cite web |url=https://www.esa.int/Our_Activities/Observing_the_Earth/Space_for_our_climate/Antarctic_glaciers_named_after_satellites |title=Antarctic Glaciers Named After Satellites |publisher=European Space Agency |date=7 June 2019 |access-date=29 September 2019}}</ref>