Editing Jason-1 (section)

== History ==
Jason-1 is the successor to the [[TOPEX/Poseidon]] mission,<ref>{{cite web|url=http://topex-www.jpl.nasa.gov/mission/topex.html|title=Ocean Surface Topography from Space|publisher=NASA/JPL|url-status=dead |archive-url=https://web.archive.org/web/20080531084646/http://topex-www.jpl.nasa.gov/mission/topex.html|archive-date=2008-05-31}} {{PD-notice}}</ref> which measured [[ocean surface topography]] from 1992 through 2005. Like its predecessor, Jason-1 is a joint project between the [[NASA]] (United States) and [[CNES]] (France) space agencies. Jason-1's successor, the [[Ocean Surface Topography Mission]]<ref>{{cite web|url=http://sealevel.jpl.nasa.gov/mission/ostm.html|archive-url=https://web.archive.org/web/20020806165124/http://sealevel.jpl.nasa.gov/mission/ostm.html|url-status=dead|archive-date=2002-08-06|title=Ocean Surface Topography from Space|publisher=NASA/JPL}} {{PD-notice}}</ref> on the [[Ocean Surface Topography Mission/Jason-2|Jason-2]] satellite, was launched in June 2008. These satellites provide a unique global view of the oceans that is impossible to acquire using traditional ship-based sampling.

Jason-1 was built by [[Thales Alenia Space]] using a [[Proteus (satellite)|Proteus]] platform, under a contract from [[CNES]], as well as the main Jason-1 instrument, the Poseidon-2 altimeter (successor to the Poseidon altimeter on-board TOPEX/Poseidon).

Jason-1 was designed to measure [[climate change]] through very precise millimeter-per-year measurements of global [[sea level change]]s. As did TOPEX/Poseidon, Jason-1 uses an [[altimeter]] to measure the hills and valleys of the ocean's surface. These measurements of [[Ocean surface topography|sea surface topography]] allow scientists to calculate the speed and direction of ocean currents and monitor global ocean circulation. The global ocean is Earth's primary [[ocean heat content|storehouse of solar energy]]. Jason-1's measurements of sea surface height reveal where this heat is stored, how it moves around Earth by ocean currents, and how these processes affect weather and climate.
[[File:Delta II 7920-10 021113-O-9999G-004.jpg|thumb|A Boeing Delta II rocket carrying the Jason 1 and Timed satellites from Space Launch Complex-2 on Dec. 7. ]]
Jason-1 was launched on 7 December 2001 from [[Vandenberg Air Force Base]], in [[California]], aboard a [[Delta II]] [[Launch vehicle]]. During the first months Jason-1 shared an almost identical orbit to TOPEX/Poseidon, which allowed for cross calibration. At the end of this period, the older satellite was moved to a new orbit midway between each Jason [[ground track]]. Jason had a repeat cycle of 10 days.

On 16 March 2002, Jason-1 experienced a sudden attitude upset, accompanied by temporary fluctuations in the onboard electrical systems. Soon after this incident, two new small pieces of [[space debris]] were observed in orbits slightly lower than Jason-1's, and [[Spectroscopy|spectroscopic analysis]] eventually proved them to have originated from Jason-1. In 2011, it was determined that the pieces of debris had most likely been ejected from Jason-1 by an unidentified, small "high-speed particle" hitting one of the spacecraft's [[Solar panels on spacecraft|solar panels]].<ref>{{cite web |url=http://orbitaldebris.jsc.nasa.gov/newsletter/pdfs/ODQNv15i3.pdf|title=New Evidence of Particle Impact on Jason-1 Spacecraft|date=July 2011|access-date=2 February 2017|archive-url=https://web.archive.org/web/20111020092342/http://orbitaldebris.jsc.nasa.gov/newsletter/pdfs/ODQNv15i3.pdf|publisher=NASA|url-status=dead|archive-date=20 October 2011}} {{PD-notice}}</ref>

Orbit maneuvers in 2009 put the Jason-1 satellite on the opposite side of [[Earth]] from the [[OSTM/Jason-2]] satellite, which is operated by the United States and French weather agencies. At that time, Jason-1 flew over the same region of the ocean that OSTM/Jason-2 flew over five days earlier. Its ground tracks fell midway between those of OSTM/Jason-2, which are about {{cvt|315|km}} apart at the [[equator]].

This interleaved tandem mission provided twice the number of measurements of the ocean's surface, bringing smaller features such as ocean eddies into view. The tandem mission also helped pave the way for a future ocean altimeter mission that would collect much more detailed data with its single instrument than the two Jason satellites now do together.<ref>{{cite web |url=http://sealevel.jpl.nasa.gov/newsroom/features/200904-1.html|title=Tandem Mission Brings Ocean Currents Into Sharper Focus|publisher=NASA/JPL|url-status=dead |archive-url=https://web.archive.org/web/20090422221414/http://sealevel.jpl.nasa.gov/newsroom/features/200904-1.html|archive-date=2009-04-22}} {{PD-notice}}</ref>

In early 2012, having helped cross-calibrate the OSTM/Jason-2 replacement mission, Jason-1 was maneuvered into its graveyard orbit and all remaining fuel was vented.<ref>[https://arstechnica.com/science/2013/07/last-transmitter-dies-finalizing-retirement-for-ocean-sensing-satellite/ "Last transmitter dies, finalizing retirement for ocean-sensing satellite"] ''Ars Technica'' Retrieved: 25 May 2017</ref> The mission was still able to return science data, measuring Earth's gravity field over the ocean. On 21 June 2013, contact with Jason-1 was lost; multiple attempts to re-establish communication failed. It was determined that the last remaining transmitter on board the spacecraft had failed. Operators sent commands to the satellite to turn off remaining functioning components on 1 July 2013, rendering it decommissioned. It is estimated that the spacecraft will remain on orbit for at least 1,000 years.<ref>[https://www.jpl.nasa.gov/news/news.php?release=2013-213 "Long-Running Jason-1 Ocean Satellite Takes Final Bow"], ''Jet Propulsion Laboratory'', Retrieved: 25 May 2017 {{PD-notice}}</ref>

The program is named after the Greek mythological hero [[Jason]].