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DESAT: This initial firing of attitude control thrusters occurred soon after solar panel deployment. This thruster activity placed MESSENGER in a stable attitude with nearly zero rotation.
TCM-1: Trajectory correction maneuver #1 removed most of the errors associated with launch and Earth orbit departure.
TCM-2: Trajectory correction maneuver #2 removed the remaining errors associated with launch and Earth orbit departure.
TCM-3: Trajectory correction maneuver #3 targeted the spacecraft for the Earth flyby aim point on August 2, 2005.
TCM-4: cancelled (not necessary)
TCM-5: Trajectory correction maneuver #5 targeted the spacecraft for the Earth flyby aim point on August 2, 2005.
TCM-6: Trajectory correction maneuver #6 provided final targeting for the spacecraft for the Earth flyby aim point on August 2, 2005 . The actual and target minimum altitudes differed by 1 km.
TCM-7: cancelled (not necessary)
TCM-8: cancelled (not necessary)
TCM-9: Trajectory correction maneuver #9 targeted the spacecraft for the first Venus flyby aim point on October 24, 2006.
CMD-1: Commanded momentum dump #1 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
TCM-10: Trajectory correction maneuver #10 provided a small adjustment to the first Venus flyby aim point on October 24, 2006.
CMD-2: Commanded momentum dump #2 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
TCM-11: Trajectory correction maneuver #11 targeted the first Venus flyby aim point on October 24, 2006 . This was the mission's first two-part TCM with two thruster sets.
TCM-12: Trajectory correction maneuver #12 targeted the first Venus flyby aim point on October 24, 2006 . The actual and target minimum altitudes differed by 52.8 km.
AMD-1: Autonomous momentum dump #1 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
TCM-13: Trajectory correction maneuver #13 targeted the second Venus flyby aim point on June 5, 2007 . This was the mission's only three-part TCM with two thruster sets.
TCM-14: cancelled (not necessary)
TCM-15: Trajectory correction maneuver #15 targeted the second Venus flyby aim point on June 5, 2007 . This small maneuver had a large (~25%) under burn.
TCM-16: Trajectory correction maneuver #16 targeted the second Venus flyby aim point on June 5, 2007 . The actual and target minimum altitudes differed by 1.4 km.
TCM-17: cancelled (not necessary)
TCM-18: Trajectory correction maneuver #18 targeted the spacecraft for the first Mercury flyby aim point on January 14, 2008 . This was the mission's second two-part TCM with two thruster sets.
TCM-19: Trajectory correction maneuver #19 targeted the first Mercury flyby aim point on January 14, 2008 . The actual and target minimum altitudes differed by 1.4 km.
TCM-20: cancelled (not necessary)
TCM-21: cancelled (not necessary)
TCM-22: cancelled (not necessary)
TCM-23: Trajectory correction maneuver #23 targeted the spacecraft for the second Mercury flyby aim point on October 6, 2008 . The actual and target minimum altitudes differed by 0.8 km.
TCM-24: cancelled (not necessary)
TCM-25: cancelled (not necessary)
TCM-26: cancelled (not necessary)
TCM-27: cancelled (not necessary)
TCM-28: cancelled (not necessary)
TCM-29: Trajectory correction maneuver #29 targeted the spacecraft for the third Mercury flyby aim point on September 29, 2009 . The actual and target minimum altitudes differed by 0.5 km.
TCM-30: cancelled (not necessary)
TCM-31: cancelled (not necessary)
TCM-32: cancelled (not necessary)
TCM-33: cancelled (not necessary)
TCM-34: cancelled (not necessary)
TCM-35: Trajectory correction maneuver #35 targeted the spacecraft for Mercury orbit insertion on March 18, 2011 . The actual and target minimum altitudes differed by 6.0 km.
CMD-3-5: Commanded momentum dumps #3-#5 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
MOI: The Mercury orbit insertion maneuver placed the spacecraft into orbit around Mercury on March 18, 2011 . The actual and target orbit periods differed by 4.2 minutes.
CMD-6-14: Commanded momentum dumps #6-#14 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-1: Orbit correction maneuver 1 lowered the spacecraft's minimum orbit altitude on June 15, 2011 . The minimum orbit altitude decreased from 505 km to 200 km.
CMD-15-19: Commanded momentum dumps #15-#19 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-2: Orbit correction maneuver 2 increased the spacecraft's orbit period on July 26, 2011 . The orbit period increased from 11.80 hr to 12.00 hr.
CMD-20-23: Commanded momentum dumps #20-#23 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-3: Orbit correction maneuver 3 lowered the spacecraft's minimum orbit altitude on September 7, 2011 . The minimum orbit altitude decreased from 470 km to 200 km.
CMD-24-29: Commanded momentum dumps #24-#29 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-4: Orbit correction maneuver 4 increased the spacecraft's orbit period on October 24, 2011 . The orbit period increased from 11.76 hr to 12.00 hr.
CMD-30-33: Commanded momentum dumps #30-#33 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-5: Orbit correction maneuver 5 lowered the spacecraft's minimum orbit altitude on December 5, 2011 . The minimum orbit altitude decreased from 442 km to 200 km.
CMD-34-42: Commanded momentum dumps #34-#42 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-6: Orbit correction maneuver 6 lowered the spacecraft's minimum orbit altitude on March 3, 2012 . The minimum orbit altitude decreased from 405 km to 200 km.
CMD-43-47: Commanded momentum dumps #43-#47 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-7: Orbit correction maneuver 7 decreased the spacecraft's orbit period on April 16, 2012 . The orbit period decreased from 11.60 hr to 9.08 hr.
OCM-8: Orbit correction maneuver 8 decreased the spacecraft's orbit period on April 20, 2012 . The orbit period decreased from 9.08 hr to 8.00 hr.
CMD-48-146: Commanded momentum dumps #48-#146 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-9: Orbit correction maneuver 9 raised the spacecraft's minimum orbit altitude on June 17, 2014 . The minimum orbit altitude increased from 114 km to 155 km.
CMD-147-156: Commanded momentum dumps #147-#156 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-10: Orbit correction maneuver 10 raised the spacecraft's minimum orbit altitude on September 12, 2014 . The minimum orbit altitude increased from 24 km to 94 km.
CMD-157-161: Commanded momentum dumps #157-#161 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-11: Orbit correction maneuver 11 raised the spacecraft's minimum orbit altitude on October 24, 2014 . The minimum orbit altitude increased from 26 km to 184 km.
CMD-162-170: Commanded momentum dumps #162-#170 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-12: Orbit correction maneuver 12 raised the spacecraft's minimum orbit altitude on January 21, 2015 . The minimum orbit altitude increased from 26 km to 105 km.
CMD-171-177: Commanded momentum dumps #171-#177 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-13: Orbit correction maneuver 13 raised the spacecraft's minimum orbit altitude on March 18, 2015 . The minimum orbit altitude increased from 11.6 km to 34.5 km.
CMD-178: Commanded momentum dumps #178 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-14: Orbit correction maneuver 14 raised the spacecraft's minimum orbit altitude on April 2, 2015 . The minimum orbit altitude increased from 5.5 km to 28.3 km.
OCM-15: Orbit correction maneuver 15 raised the spacecraft's minimum orbit altitude on April 6, 2015 . The minimum orbit altitude increased from 13.1 km to 25.7 km.
OCM-15A: Orbit correction maneuver 15A raised the spacecraft's minimum orbit altitude on April 8, 2015 . The minimum orbit altitude increased from 18.2 km to 29.1 km.
CMD-179: Commanded momentum dumps #179 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-16: Orbit correction maneuver 16 raised the spacecraft's minimum orbit altitude on April 14, 2015 . The minimum orbit altitude increased from 6.5 km to 13.5 km.
CMD-180: Commanded momentum dumps #180 used 8 of the smallest thrusters to reduce the spacecraft's angular momentum to a safe level.
OCM-17: Orbit correction maneuver 17 raised the spacecraft's minimum orbit altitude on April 24, 2015 . The minimum orbit altitude increased from 8.3 km to 18.2 km.
OCM-18: Orbit correction maneuver 18 raised the spacecraft's minimum orbit altitude on April 28, 2015 . The minimum orbit altitude increased from 5.3 km to 6.3 km.
Time: |
Units are hours:minutes:seconds in UTC (Universal Time Coordinated). |
Distance: |
Distance is measured at the start of the propulsive event. Distance is between the spacecraft and the center of the Earth or Sun. |
AU: |
Astronomical Unit. One AU, the average distance between the Sun and Earth, equals 149,597,870.691 km. |
One-way light time: |
This is the time required for signals to travel from the spacecraft to Earth, assuming that the signals travel at the speed of light in a vacuum. |
ΔV: |
Delta-V is the velocity change imparted to the spacecraft in direction (x, y, z) during the propulsive event. |
Nav: |
This denotes that the value is reported by the Navigation team. The observations of the change in spacecraft orbit made by this team lead to the most accurate assessment of velocity change (delta-V) imparted to the spacecraft. |
EME2000: |
This reference frame (or coordinate system) is based on the mean (average) orientation of Earth’s equator on January 1, 2000 , at noon ephemeris time. |
Duration: |
This is the time required for the thrusters to impart the intended delta-V to the spacecraft trajectory. Duration does not include post-manuever thruster activity needed to fully stabilize the spacecraft attitude. |
Propulsive ΔV: |
This measure of fuel usage adds the delta-V observed as a velocity change imparted to the orbit to the delta-V used to control the orientation (or attitude) of the spacecraft. While the attitude control delta-V does not change the spacecraft’s orbit, this delta-V describes how much fuel is needed to keep the spacecraft pointed in the right direction during propulsive events. |
Remaining ΔV: |
This is the maximum expected amount of velocity change that the remaining propellant can impart to the spacecraft trajectory, given the current assumptions concerning which thrusters will be used for future planned maneuvers. |