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The Afternoon Constellation

The Afternoon Constellation - A-Train

A-Train Historical Graphics


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.








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.








A-Train historical image
web view | hi-resolution
(approximately March 2008)

A-train historical image
web view | hi-resolution
(approximately March 2009)

A-train historical image
web view | hi-resolution
(approximately February 2010)

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 historical image
web view | hi-resolution
(approximately June 2011)

A-Train historical image
web view | hi-resolution
(after June 2011)

Afternoon Constellation
web view | hi-resolution
(after June 2011)

A-train constellation satellite line-up
web view | hi-resolution
(June 2012)

A-train constellation satellite line-up
web view | hi-resolution
(June 2013)

A-train constellation satellite line-up
web view | hi-resolution
(June 2017)

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.


























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 reposititioned 108 seconds behind CALIPSO.





















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











Note time seperation adjustment between Aura and CloudSat.



















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 historical image
web view | hi-resolution
(2010) Constellation Flying
web view | hi-resolution
(late 2011 to mid 2012) Constellation Flying
web view | hi-resolution
(2013) Constellation Flying
web view | hi-resolution
(2017)

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.
















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.














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
















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













This image shows the A-Train satellites in 2010 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. GCOM-W1 did not launch until May 18, 2012, and therefore does not appear in this graphic.


























This table, from 2010, provides an overview of each satellite‘s instruments—including the instruments onboard the Glory spacecraft.



























Afternoon Constellation Fact