# Altimetry missions

The {{cci_version}} of CCI Sea State datasets includes for altimetry 
the missions described hereafter.

## ERS-1

**Launch date** : July 17, 1991

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**End of life date** : March 31, 2000

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**Agency** : ESA

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**Instrument** : RA

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**Orbit characteristics** : 
- Orbit type : Sun-synchronous near-circular polar orbit
- Inclination : 98.52 degrees
- Altitude : 785km
- Nodal Period : approximately 100min (14,3 orbits per day)
- Repeat Cycle : 35 days

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**Orbit life**:
- Tandem phase : from August 17, 1995 to June 6, 1996
- Degraded status : from June 2, 1996 to March 11, 2000



## TOPEX

**Launch date** : August 10, 1992

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**End of life date** : January 18, 2005

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**Agency** : CNES/NASA

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**Instrument** : NRA-SSALT

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**Orbit characteristics** : 
- Orbit type : Non-heliosynchronous (prograde orbit)
- Inclination : 66 degrees
- Altitude : 1336 km
- Nodal Period : 6745.72s
- Repeat Cycle : 9.9156 days

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**Orbit life** :
- From August 2008 to September 2002 : in its nominal orbit.
- Interleaved orbit from September 16, 2002 to October 18, 2005


## ERS-2

**Launch date** : April 21, 1995

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**End of life date** : July 6, 2011

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**Agency** : ESA

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**Instrument** : RA

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**Orbit characteristics** : 
- Orbit type : Sun-synchronous polar orbit (retrograde orbit)
- Inclination : 98.52 degrees
- Altitude : 785 km 
- Nodal Period : approximately 100min (14,3 orbits per day)
- Repeat Cycle : 35 days

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**Orbit life** :
- Tandem phase : from August 17, 1995 to June 2, 1996 
- Degraded phase : from June 1, 2003 to July 6, 2011



## JASON-1

**Launch date** : December 7, 2001

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**End of life date** : July 1, 2013

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**Agency** : CNES/NASA

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**Instrument** : Poseidon-2

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**Orbit characteristics** : 
- Orbit type : Non-heliosynchronous (prograde orbit)
- Inclination : 66 degrees
- Altitude : 1336 km
- Nodal Period : 6745.72s
- Repeat Cycle : 9.9156 days

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**Orbit life** :
- Same orbit as Topex/Poseidon
- Tandem phase : end on August 15, 2002 
- Interleaved orbit : from February 10, 2009 to May 7, 2012 
- Geodetic orbit : from May 7, 2012 to July 1, 2013




## JASON-2

**Launch date** : June 20, 2008

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**End of life date** : October 1, 2019

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**Agency** : CNES/NASA/EUMETSAT/NOAA

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**Instrument** : Poseidon-3

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**Orbit characteristics** : 
- Orbit type : Non-heliosynchronous (prograde orbit)
- Inclination : 66 degrees
- Altitude : 1336 km
- Nodal Period : 6745.72s

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**Orbit life** :
- From June 2008 to October 2016 : in its nominal orbit.
- Tandem phase with Jason-2 from February 12th to October 2nd 2016
- Interleaved orbit : from October 14, 2016 to January 1, 2017
- Geodetic orbit : from July 10, 2017 to October 1, 2019




## JASON-3

**Launch date** : January 17, 2016

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**End of life date** : Active mission

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**Agency** : CNES/NASA/EUMETSAT/NOAA

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**Instrument** : Poseidon-3B

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**Orbit characteristics** : 
- Orbit type : Non-heliosynchronous (prograde orbit)
- Inclination : 66 degrees
- Altitude : 1336 km
- Nodal Period : 6745.72s
- Repeat Cycle : 9.9156 days

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**Orbit life** :
- Tandem phase with Jason-2 from February 12th to October 2nd 2016
- From January 2016 to April 2022 : in its nominal orbit.
- Interleaved orbit : from April 25, 2022


## ENVISAT

**Launch date** : March 1, 2002

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**End of life date** : June 8, 2012

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**Agency** : ESA 

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**Instrument** : RA-2

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**Orbit characteristics** : 
- Orbit type : Sun-synchronous (near-polar orbit)
- Inclination: 98.55 degrees
- Altitude: 799.38 km
- Repeat cycle: 35 days

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**Orbit life** :

- From March 2002 to April 2012: Operated in its nominal orbit.
- Tandem phase : from June 18, 2003 to October 20, 2003


## CRYOSAT-2

**Launch date** : April 8, 2010

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**End of life date** : Still operational

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**Agency** : ESA

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**Instrument** : SIRAL

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**Orbit characteristics** :

- Orbit type: Non-sun-synchronous (prograde orbit)
- Inclination: 92 degrees
- Altitude: 717 km
- Repeat cycle: 369 days


## SARAL

**Launch date** : February 25, 2013

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**End of life date** : Still operational 

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**Agency** : CNES/ISRO 

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**Instrument** : AltiKa

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**Orbit characteristics** :
        
- Orbit type: Sun-synchronous (near-polar orbit)
- Inclination: 98.55 degrees
- Altitude: 800 km
- Repeat cycle: 35 days



## SENTINEL-3A

**Launch date** : February 16, 2016

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**End of life date** : Still operational

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**Agency** : ESA 

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**Instrument** : SRAL

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**Orbit characteristics** :
        
- Orbit type: Sun-synchronous (near-polar orbit)
- Inclination: 98.65 degrees
- Altitude: 814.5 km
- Repeat cycle: 27 days 

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**Orbit life** :
- Tandem phase : from June 7, 2018 to October 16, 2018



## SENTINEL-3B

**Launch date** : April 25, 2018

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**End of life date** : Still operational

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**Agency** : ESA 

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**Instrument** : SRAL

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**Orbit characteristics** :

- Orbit type: Sun-synchronous (near-polar orbit)
- Inclination: 98.65 degrees
- Altitude: 814.5 km
- Repeat cycle: 27 days (in tandem with Sentinel-3A)

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**Orbit life** :
        
- Operating in tandem with Sentinel-3A for better spatial and temporal coverage.
- Tandem phase : from June 7, 2018 to October 16, 2018


## SENTINEL-6A

**Launch date** : November 21, 2020

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**End of life date** : Still operational

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**Agency** : ESA/EUMETSAT/EU/CNES/NOAA/NASA

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**Instrument** : Poseidon-4

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**Orbit characteristics** :

- Orbit type: Non-sun-synchronous (prograde orbit)
- Inclination: 66 degrees
- Altitude: 1336 km
- Repeat cycle: 9.9156 days