Landsat 8 and 9 Maneuvers

By Landsat Missions

In order to maintain a consistent equatorial crossing time of 10:12 a.m. (+/- 5 minutes), the Landsat spacecrafts must occasionally undergo maneuvers using the satellite's propulsion subsystem to fire thrusters and bring about a change in the orbital elements.

When maneuvers are executed, science imaging may be briefly suspended.

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Landsat Maneuver Definitions

Inclination Adjustment Maneuver (IAM): An IAM is commonly referred to as a Delta-Inclination (Delta-I) maneuver. The maneuver is performed in the cross-track direction (i.e. perpendicular to the direction the spacecraft is moving.) An IAM changes the angle of the equatorial plane to the orbital plane. This type of maneuver is performed periodically (nominally once per year) to maintain the mission's Mean Local Time (MLT).
Drag Make-Up (DMU) Maneuver: This type of maneuver may also be referred to as a Delta-Velocity (Delta-V) maneuver (or an orbit altitude adjustment maneuver). It is used to raise (or lower) the orbit's semi-major axis. A DMU is a specific type of Delta-V (positive) which increases the orbital velocity thus increasing the orbital altitude and is used to counteract the effects of atmospheric drag on the spacecraft and maintain orbit circulation as well as maintain the strict constraints on the projected spacecraft ground track. (A negative "DMU" is a retrograde maneuver to lower the altitude. However, Landsat 8 has not performed one of these operationally.)
Risk Mitigation Maneuver (RMM): This type of maneuver is also a Delta-V maneuver to change the orbit altitude. An RMM is executed to avoid orbital debris and may be either a velocity increase (prograde maneuver - semi-major axis increase) or a velocity decrease (retrograde maneuver - semi-major axis decrease). An RMM is only performed if the flight operations team determines the Probability of Collision (Pc) meets certain thresholds as determined by complex conjunction assessments.

When maneuvers impact science imaging onboard Landsat 8 or Landsat 9, a news headline is posted on the Landsat Mission Website and distributed to subscribers signed up to receive headlines. Please search the list of posted news on the Landsat Headlines webpage for reported maneuvers.

See the Landsat 7 Maneuvers webpage for more information on Landsat 7 maneuvers.