Stories
Slash Boxes
Comments

SoylentNews is people

posted by cmn32480 on Wednesday August 24 2016, @06:26PM   Printer-friendly
from the hope-it-hasn't-been-taken-over-by-aliens dept.

NASA Regains Contact With Long-silent Solar Science Spacecraft

SpaceNews reports that NASA has made contact with a long-dead (almost exactly 2 years) solar science spacecraft.

NASA said that the Deep Space Network (DSN) established a lock on a carrier signal from the STEREO-B spacecraft at 6:27 p.m. Eastern Aug. 21. NASA monitored the signal for several hours, and plans additional contacts with the spacecraft to assess the state of the spacecraft.

The contact was the first time NASA had made contact with STEREO-B since Oct. 1, 2014. At that time ground controllers were testing the spacecraft's "command loss timer," which reboots the spacecraft's computer after three days without contact with the ground, in anticipation of an extended communications outage. At the end of the test, controllers only received a brief, weak signal from the spacecraft before losing contact entirely.

In recent months, NASA had carried out regular efforts to restore contact with STEREO-B, transmitting instructions in the blind in the hopes the spacecraft would be able to receive them and respond. NASA started those efforts late last year once STEREO-B was far enough from the sun, as seen from the Earth, so that radio interference from the sun was no longer an issue.

[...] A subsequent analysis of the limited telemetry STEREO-B returned before losing communications indicated to engineers that the spacecraft lost attitude control. "The telemetry showed that the Inertial Measurement Unit, or IMU -- which tells the spacecraft if and how fast it's rotating -- failed in a way we didn't expect," said Dan Ossing, STEREO mission operations manager, in a NASA statement last December. "Rather than cutting out altogether, it was feeding incorrect information into the guidance and control computer."

That incorrect information, engineers believe, led the spacecraft to think it was spinning even though it was not. The spacecraft, in turn, fired thrusters to correct the perceived spin, which instead caused the spacecraft to spin up in reality. That would have limited the ability of the spacecraft's solar panels to generate power, hindering recovery efforts.

NASA Reestablishes Contact With STEREO-B Satellite

One of the Solar Terrestrial Relations Observatories, a pair of Sun-observing satellites, has made contact with NASA's Deep Space Network after nearly two years of silence:

The DSN established a lock on the STEREO-B downlink carrier at 6:27 p.m. EDT. The downlink signal was monitored by the Mission Operations team over several hours to characterize the attitude of the spacecraft and then transmitter high voltage was powered down to save battery power. The STEREO Missions Operations team plans further recovery processes to assess observatory health, re-establish attitude control, and evaluate all subsystems and instruments.

Communications with STEREO-B were lost during a test of the spacecraft's command loss timer, a hard reset that is triggered after the spacecraft goes without communications from Earth for 72 hours. The STEREO team was testing this function in preparation for something known as solar conjunction, when STEREO-B's line of sight to Earth – and therefore all communication – was blocked by the sun.

Also at TechCrunch and the Washington Post. See also: NASA's STEREO site.


Original Submission #1Original Submission #2

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 2) by FatPhil on Thursday August 25 2016, @08:43AM

    by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Thursday August 25 2016, @08:43AM (#392919) Homepage
    I.e. became a stroppy teenager. It has been communicating these last couple of years, it's just that it's only been saying "I haaaate you".
    --
    Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
    Starting Score:    1  point
    Karma-Bonus Modifier   +1  

    Total Score:   2