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.

CURRENT STATUS:

Science Instrument Status:
• All the science instruments, including the K-Band ranging instrument, the accelerometer, the star cameras and the GPS receiver, are now collecting all science data nominally.
  


Both satellites are operating with minimal thermal control (Table-G).
GRACE-1 in Table-G since April 18, 2011
GRACE-2 in Table-G since April 28, 2011


beta_prime: -59 deg; Altitude: 449 km; Separation: 216 km

PEAK beta_prime= -80 degrees, February 12, 2012
NEXT beta_prime= 0 event, May 03, 2012
PEAK beta_prime= +75 degrees, July 24, 2012

SCIENCE DATA PRODUCTS:

Jan-2011: Only Level-1 data products delivered
Feb-2011: (Feb 07-Feb28) All data products delivered to archives
Mar-2011: (Mar 01-Mar 31) All data products delivered to archives
Apr-2011: (Apr 01-Apr 30) All data products delivered to archives
May-2011: (May-01 to May-31) All data product delivered to archives
June-2011: Only Level-1 data products delivered
July-2011: (Jul-07 to Jul-31) All data products delivered to archives
August-2011: (Aug-01 to Aug-31) All data products delivered to archives
September-2011: (Sep-01 to Sep-30) All data products delivered to archives
October-2011: (Oct-01 to Oct-31) All data products delivered to archives

BACKGROUND:

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.