Landsat 7 Maneuvers

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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. perpindicular 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). Landsat has a requirement for a MLT equatorial crossing of 10:00 AM +/- 15 minutes.
  
   
• 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.

Historical Landsat 7 Maneuvers

September 22, 2020: The NASA Landsat 7 Flight Dynamics Team commanded the spacecraft during a drag make-up (DMU) maneuver starting at 17:08:00 UTC. The maneuver lasted 6 seconds.

February 7-9, 2017 (Landsat 7's FINAL Delta-I Maneuver): Landsat 7's final Delta-Inclination (Delta-I) maneuver on Tuesday February 7, 2017 (DOY 38) caused no Landsat 7 data to be acquired starting at 12:15 UTC (7:15 am CT) on DOY 38 until 03:30 UTC on February 9, 2017 (DOY 40) (10:30 pm CT February 8, 2017).

Since launch in 1999, Delta-I maneuvers have kept the spacecraft in the correct orbit to ensure the satellite maintains its 10:00 am local mean time (LMT) acquisitions. After this last maneuver, the satellite will drift in its inclination over the next four years, falling back to 9:15 am LMT in 2020. This is in preparation of the launch of Landsat 9 in late 2020.

By the time the Landsat 9 satellite launches in late 2020, Landsat 7 will be at a lower orbit, allowing Landsat 9 to move into the 705-kilometer standard orbit altitude after launch. Once Landsat 7 reaches a 9:15 am (LMT) acquisition time, it will no longer be providing valid science data and the satellite will be decommissioned. Landsat 9 will allow the continuance of an 8-day offset for acquisitions with Landsat 8.

September 29 - October 1, 2015: No Landsat 7 data were acquired from 12:00 UTC (7:00 am CT) September 29, 2015 (DOY 272) until 04:30 UTC on October 1, 2015 (DOY 274) (11:30 pm CT September 30, 2015) due to a Delta-Inclination (Delta-I) maneuver.

February 10-11, 2015: No Landsat 7 data were acquired from 15:00 UTC (9:00 am CT) February 10, 2015 (DOY41) until 21:15 UTC (3:15 pm CT) on February 11, 2015 (DOY42) due to a Delta-Inclination (Delta-I) maneuver.

September 27-29, 2014 (Landsat 7 acquisitions suspended): On Saturday, September 27, 2014, the Landsat 7 satellite stopped acquiring data due to an onboard telemetry unit issue. Investigations into the issue determined that the primary remote telemetry command unit encountered an error, and switched to the secondary. There were no issues detected to the functionality of the satellite. Imaging was suspended from 20:20 UTC (3:20 pm CT) on September 27 until 21:23 UTC (4:23 pm CT) on September 29, 2014 when nominal acquisitions resumed.

September 9-10, 2014: No Landsat 7 data were acquired from 9:30 CT (14:30 UTC) on September 9, 2014 (DOY 252) until 14:00 UTC (9:00 CT) on September 10, 2014) DOY 253 due to a Landsat 7 Delta-Inclination (Delta-I) maneuver. February 4-5, 2014: No Landsat 7 data were acquired from 14:30 UTC (8:30 am CT) on February 4, 2014 (DOY 35) until 20:15 UTC (2:15 pm CT) on February 5, 2014 (DOY 36) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver. August 6-7, 2013: No Landsat 7 data were acquired from 11:30 UTC (6:30 am CT) on August 6, 2013 (DOY 218) until 23:00 UTC (6:00 pm CT) on August 7, 2013 (DOY 219) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

May 15-16, 2012: No Landsat 7 data were acquired from 11:30 UTC (6:30 am CT) on May 15, 2012 (DOY 136) until 11:30 UTC (3:30 pm CT) on May 16, 2012 (DOY 137) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

April 17, 2012 (Debris Avoidance): Landsat 7 maneuvered out of the path of a piece of debris that was on a collision course with the spacecraft on April 17, 2012 (DOY 108). This move immediately affected the area of data imaged. The geographic coverage drifted to the west until the easternmost portion of the scene was missing as compared to previous acquisitions. The largest offset was seen around April 25, 2012 (DOY 116). The westward movement continued until the USGS Flight Operations Team maneuvered and re-positioned the satellite to its proper orbit. This process caused data to be outside of WRS-2 ‘box’ until May 30, 2012 (DOY 150).

October 5-6, 2011: No Landsat 7 data were acquired from 13:30 UTC (8:30 am CT) on October 4, 2011 (DOY 277) until 02:00 UTC on October 6, 2011 (DOY 278) (11:00 pm CT October 5, 2011 (DOY 277) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

March 5, 2011 (Antenna error): No Landsat 7 data are available for the following path/rows acquired on March 5, 2011 (DOY64) due to an antenna error:

Path 1 Rows 52 to 62

Path 218 Row 69, Rows 111 to 116

September 28-30, 2010: No Landsat 7 data were acquired from 13:00 UTC (8:00 am CT) on September 28, 2010 (DOY 271) until 03:30 UTC on September 30, 2009 (DOY 273) (10:30 pm CT September 28, 2010 (DOY 272) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 6-8, 2009: No Landsat 7 data were acquired from13:30 UTC (8:30 am CT) on October 6, 2009 (DOY 279) until 05:00 UTC (12:00 am CT) on October 8, 2009 (DOY 281) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 7-9, 2008: No Landsat 7 data were acquired from 13:30 UTC (8:30 am CT) on October 7, 2008 (DOY 281) until 03:30 UTC on October 9, 2008 (DOY 283) (10:30 pm CT October 8, 2008 DOY 282) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 2-4, 2007: No Landsat 7 data were acquired from 13:30 UTC (8:30 am CT) on October 2, 2007 (DOY 275) until 03:30 UTC on October 4, 2007 (DOY 277) (11:00 pm CT October 3, 2007 DOY 276) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 3-5, 2006: No Landsat 7 data were acquired from 12:30 UTC (7:30 am CT) on October 3, 2006 (DOY 276) until 02:00 UTC on October 5, 2006 (DOY 278) (9:00 pm CT October 4, 2006 DOY 277) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 4-6, 2005: No Landsat 7 data were acquired from 12:30 UTC (7:30 am CT) on October 4, 2005 (DOY 277) until 01:00 UTC on October 6, 2006 (DOY 279) (8:00 pm CT October 5, 2005 DOY 278) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 5-6, 2004: No Landsat 7 data were acquired from 12:00 UTC (7:00 am CT) on October 5, 2004 (DOY 279) until 22:00 UTC (5:00 pm CT) on October 6, 2004 (DOY 280) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 7-9, 2003: No Landsat 7 data were acquired from 12:00 UTC (7:00am CT) on October 7, 2003 (DOY 280) until 02:15 UTC on October 9, 2003 (DOY 282) (9:15 pm CT October 8, 2003-DOY 281) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

September 3-17, 2003 (Scan Line Corrector Recovery Attempt): Landsat 7 data acquisitions were suspended starting on September 3, 2003 (DOY 246), to allow engineers to employ recovery attempt procedures to the Scan Line Corrector (SLC), which failed on May 31, 2003 (DOY151). Acquisitions resumed September 17, 2003 (DOY 260).

May 31, 2003 (Scan Line Corrector malfunction): On May 31, 2003 (DOY 151), the Scan Line Corrector (SLC), which compensates for the forward motion of the satellite, failed, suspending Landsat 7 data availability temporarily. After investigations, data acquired during the period of discovery were reprocessed and cataloged as Landsat 7 SLC-off data.

October 8-9, 2002: No Landsat 7 data were acquired from 12:00 UTC (7:00am CT) on October 8, 2002 (DOY 281) until 10:30 UTC (5:30 pm CT) on October 9, 2002 due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 9-11, 2001: No Landsat 7 data were acquired from 12:30 UTC (7:30am CT) on October 9, 2001 (DOY 282) until 05:00 UTC (12:00 am CT) on October 11, 2001 (DOY284) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

October 11-12, 2000: No Landsat 7 data were acquired from12:00 UTC (7:00am CT) on October 11, 2000 (DOY 285) until 20:00 UTC (3:00 pm CT) on October 12, 2000 (DOY 286) due to a Landsat 7 Delta-Inclination (Delta-I) maneuver.

For more information on Landsat 8 and Landsat 9 maneuvers, please visit the Landsat 8 and 9 Maneuver webpage. When maneuvers impact science imaging onboard Landsat 8 or 9, a Landsat Headline is posted on the Landsat Mission Website and distributed to subscribers signed up to receive headlines. Please see the Landsat Headlines webpage for historical Landsat 8 and 9 maneuver information.