After a second reaction wheel anomaly on 26 August 2020 CloudSat returned to operation in December of 2021 in ACT-TWO (Attitude Control Through Two Wheel Operations) DO-Op (Daylight-Only Operations) mode, no longer in formation with CALIPSO.
Start: 16 Dec 2021 (Day 350) 14:27:41
Starting on July 5th, 2019 and continuing through August 26th, 2020, the apparent height of the surface in the radar profiles is not consistent with the Digital Elevation Map (DEM) that has been used with all CloudSat operational products throughout the mission. The mismatch is a result of an error in the satellite pointing or timing data or both. While still under investigation, the present the cause has not been isolated. Rather than further delaying the release of these data, they are being released as-is with the pointing/timing error. Fundamentally, this means there is a substantially larger uncertainty in the location where the radar beam intersects the surface that may be as large as 10 km.
Start: 11 Jul 2019 (Day 192) 00:00:00
End: 26 Aug 2020 (Day 239) 19:25:23
CloudSat is joined by CALIPSO, forming the C-Train.
Start: 10 Oct 2018 (Day 283) 00:00:00
End: 10 Jul 2019 (Day 191) 23:59:59
CloudSat exited the A-Train on February 22nd, 2018 after a reaction wheel anomaly.
Start: 3 May 2018 (Day 123) 07:25:00
End: End: 10 Oct 2018 (Day 283) 00:00:00
Although CloudSat continues to only operate during the sunlit portion of the orbit, epoch 06 started when CloudSat returned to the A-Train formation on May 15th, 2012.
Data products once again use MODIS and CALIPSO ancillary data although the overlap with CALIPSO is degraded because fewer formation flying maneuvers are performed.
Start: 15 May 2012 (Day 136) 00:49:00
End: 12 Jan 2018 (Day 12) 15:15:56
A battery anomaly on April 17th, 2011 caused the spacecraft to stop collecting data and lose formation with the A-Train.
The radar was turned back on in November 2011 and now collects data only during the sunlit portion of the orbit.
Epoch 05 represents this new operating paradigm.
In addition, the spacecraft remained outside of the A-Train formation so all data products were processed in radar-only mode without MODIS or CALIPSO data.
The impact of the missing MODIS data on the CloudSat products is still being assessed and the combined radar/lidar products (2B-GEOPROF-LIDAR, 2B-CLDCLASS-LIDAR, and 2B-FLXHR-LIDAR) are not available.
Start: 27 Oct 2011 (Day 300) 23:28:21
End: 15 May 2012 (Day 136) 00:49:00
Marks the beginning of a period where the CPR pulse rate will be periodically reduced, or increased, to manage the power draw on the battery (due to the reduced power margin as the battery ages).
The increased or reduced pulsing with induce a slight change in sensitivity.
The number of pulses can be found in the 1B-CPR field RayStatus_pulsesTx.
The pulse rate will likely continue to be adjusted, seasonally, for the duration of the mission.
Start: 15 Feb 2011 (Day 46) 18:06:30
End: 17 Apr 2011 (Day 107) 18:17:31
Epoch 02 ended when a battery anomaly forced the CPR offline.
It was brought back into operations with a slightly reduced pulse rate that decreases the radar sensitivity by approximately 0.25 dB.
Epoch 03 tags the modified operating parameters.
Start: 15 Jan 2010 (Day 15) 18:24:56
End: 15 Feb 2011 (Day 46) 18:06:30
Increased specular reflection due to the nadir-pointing instrument caused an increase in ground clutter, so the spacecraft orientation was changed again so that the CPR pointed 0.16 degrees in the forward (along-track) direction.
Start: 15 Aug 2006 (Day 227) 20:56:31
End: 7 Dec 2009 (Day 341) 11:43:22
The pointing error was corrected and the spacecraft was oriented so that the CPR pointed to nadir.
Start: 7 Jul 2006 (Day 188) 14:14:02
End: 15 Aug 2006 (Day 227) 20:56:31
During the initial phase of the mission it was unknown that the CPR was pointing off-nadir 1.7021 degrees in the forward (along-track) direction and 0.1314 degress to the right (across-track).
Start: 2 Jun 2006 (Day 153) 13:42:23
End: 7 Jul 2006 (Day 188) 14:14:02