Mission Operations Status (Updated: 2013-Sept-25)
The GRACE Operations Status depends on the health of the battery and the duration within each orbit when the battery is in use. The Status will be updated here approximately every week.
Science Instrument Status:
- The mission has resumed full science data collection since UTC 07:50, Sep 24 2013, after approximately 49 days of outage.
- The K-Band Ranging system was turned-on on both satellites at UTC 07:50, Sep 24 2013.
- The Accelerometers were turned-on at UTC 10:35 Sep 13 2013 (GRACE-1), and at UTC 08:33 Sep 16, 2013 (GRACE-2).
- The GPS and star camera data has been collected continuously throughout.
beta_prime: -29 deg; Altitude: 430 km; Separation: 169 km
PEAK beta_prime=-75 deg, Nov 16, 2013
NEXT beta_prime=0 event, Feb 02, 2014
PEAK beta_prime=77 deg, Apr 22, 2014
SCIENCE DATA PRODUCTS:
- 2011: Level-2 and Level-1B data products were delivered for every month except the following spans, for which only partial Level-1B data were delivered:
- Jan-01 to Feb-06, 2011
- Jun-01 to Jul-06, 2011
- Nov-17 to Dec-12, 2011
- 2012: Level-2 and Level-1B data products were delivered for every month except the following spans, for which only partial Level-1B data were delivered:
- Apr-20 to May-31, 2012
- Sep-26 to Nov-05, 2012
- Jan 2013: All Level-2 and Level-1B data products delivered to archives
- Feb 2013: All Level-2 and Level-1B (until Feb 26, 2013) delivered to archives
- Mar 2013: Only partial Level-1B products (Feb 27, 2013 to Apr 10, 2013) delivered to archives
- Apr 2013: All Level-2 and level-1B products (Apr 11, 2013 to Apr 30, 2013) delivered to archives
- May 2013: All Level-2 and Level-1B products delivered to archives
- Jun 2013: All Level-2 and Level-1B products delivered to archives
- Jul 2013: All Level-2 and Level-1B products delivered to archives
The GRACE Science Operations concept for the remainder of the mission is driven by the intersection of two factors. First is the project decision to operate the spacecrafts in a manner that maximizes the remaining lifetime, so that the longest possible climate data record is available from GRACE. The second is the degraded battery capacity that limits the availability of the power in certain orbital configurations.
The GRACE orbit plane precesses at -1.117 degrees/day relative to the Sun, such that the Sun is in the orbit plane every 161 days. Due to the power system status and desire for longevity, this event will henceforth define a 161-day work cycle for science operations. As long as the beta_prime angle (angle between the orbit plane and the Earth-Sun line) is greater than 69 degrees, the satellite operates using power only from its solar array. For smaller beta_prime angles, the satellites operates partly using the arrays, and partly using the battery. When beta_prime is near zero (i.e. Sun is in the orbit plane), the battery may be used for as much a 40 minutes out of 90 minutes in each orbit. Near beta_prime=0 events, the mission operations status depends on the battery health and operating environment.
This Status will be updated here approximately every week.