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History of the A-Train in Graphics

The Aqua/Aura Afternoon Constellation
This graphic, from around January 2003, illustrates the relative satellite positions planned at that time. The Afternoon Constellation had recently adopted the name “A-Train”—in reference to Billy Strayhorn‘s jazz standard Take the A-Train—because Aqua (launched May 4, 2002) and Aura (launched July 15, 2004) were the first to join the fleet and both of their names start with the letter “A,” and also because the local time equatorial crossing is in the afternoon.
NASA
The A-Train, March 2003
This graphic of the A-Train satellites is from around March 2003. Listed under each satellite‘s name is its equatorial crossing time (local time). Note that CALIPSO trails CloudSat by only 15 seconds to allow for synergy between Aqua, CloudSat, and CALIPSO.
NASA

These three images show how the A-Train configuration changed from 2008-2010. Between March 2008 and March 2009, Aura moved closer to the rest of the A-Train (as indicated by the seconds in between). By February 2010, PARASOL had lowered from A-Train orbit. GCOM-W1 (launched in May 2012) and OCO-2 (scheduled for launch in 2014) were also added to the graphic.

A-Train, March 2008
A-Train, March 2008
NASA
A-Train, March 2009
A-Train, March 2009
NASA
A-Train, February 2010
A-Train, February 2010
NASA

In the June 2011 graphic, the Glory spacecraft is shaded gray to indicate its launch failure on March 4, 2011. After June 2011, the Glory spacecraft was removed from the graphic completely.

A-Train June 2011 with Glory
A-Train June 2011
NASA
A-Train after June 2011
A-Train after June 2011
NASA

CloudSat developed battery issues in September 2011 and temporarily left the A-Train. In mid-July 2012, CloudSat re-enters the A-Train, but is repositioned 108 seconds behind CALIPSO.

A-Train after June 2011, Cloudsat reposition
A-Train after June 2011
NASA
A-Train June 2012
A-Train June 2012
NASA

On December 18, 2013, PARASOL ceases operation and fully exits the A-Train.

A-Train June 2013
A-Train June 2013
NASA

Note time separation adjustment between Aura and CloudSat.

A-Train June 2017
A-Train June 2017
NASA

Prior to November 16, 2011, PARASOL flew 15 seconds behind CALIPSO‘s control box, as depicted in the graphic from 2010. On that date, PARASOL was lowered a second time to 9.5 km below A-Train orbit, hence PARASOL‘s placement in the graphic from 2011. OCO-2 was also added to the 2011 graphic. The first lowering of PARASOL occurred in December 2009.

A-Train Control Boxes 2010
A-Train Control Boxes 2010
NASA
A-Train Control Boxes 2011
A-Train Control Boxes 2011
NASA
A-Train Control Boxes 2012
A-Train Control Boxes 2012
NASA
A-Train Control Boxes 2013
A-Train Control Boxes 2013
NASA

This image shows the order and relative distance between the satellites that made up the A-Train in 2010. Note that GCOM-W1 and OCO-2 are not depicted. Also note that prior to maneuvers that followed an April 2011 battery anomaly, CloudSat flew ahead of CALIPSO.

A-Train Orbit Tracks 2011
A-Train Orbit Tracks 2011
NASA

In mid-November 2011, PARASOL is lowered to 9.5 km below the A-Train and continues operations. GCOM-W1 joins the A-Train on June 29, 2012. In mid-July 2012, CloudSat is repositioned 108 seconds behind CALIPSO.

A-Train Orbit Tracks 2012
A-Train Orbit Tracks 2012
NASA

PARASOL leaves the A-Train and is decommissioned on December 18, 2013.

A-Train Orbit Tracks 2013
A-Train Orbit Tracks 2013
NASA

OCO-2 joins the A-Train in July 2014.

A-Train Orbit Tracks 2017
A-Train Orbit Tracks 2017
NASA

These images show the A-Train satellites as if looking down on the entire constellation from orbit. The satellites travel from south to north (bottom to top in this image). The colorful bars across each satellite illustrate the scanning swath of several instruments.

A-Train Field of View 2010
A-Train Field of View 2010
NASA
A-Train Field of View 2012
A-Train Field of View 2012, adding GCOM-W1
NASA

These tables provide an overview of each satellite‘s instruments.

A-Train Instruments 2010
A-Train Instruments 2010
NASA
A-Train Instruments 2012
A-Train Instruments 2012
NASA
A-Train Instruments 2019
A-Train Instruments 2019
NASA