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  ISS and orbital debris: maneuvers and misses

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Author Topic:   ISS and orbital debris: maneuvers and misses
Robert Pearlman
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Posts: 29191
From: Houston, TX
Registered: Nov 1999

posted 07-29-2010 11:15 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA update (July 29, 2010)
Mission Control monitoring debris near station

Mission Control Centers in the U.S. and Russia are keeping a close eye on a piece of debris from a Chinese satellite.

Earlier in the week, tracking data on the debris showed that it would pass near the station, but not close enough to require a debris avoidance maneuver.

Early Thursday, however, new tracking data on the object showed that it might pass close enough to require the crew to take shelter in their Soyuz spacecraft when the debris makes its closest approach to the station at 1:47 p.m. EDT.

Additional tracking data is expected soon, but the object has proven difficult to track precisely.

In the meantime, the crew is continuing its normal duties in support of station research and maintenance.

For more about orbital debris and how the International Space Station team tracks and responds to threats, see: Orbital debris and the International Space Station

Robert Pearlman
Editor

Posts: 29191
From: Houston, TX
Registered: Nov 1999

posted 07-29-2010 01:17 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA update (July 29, 2010)
Space Debris No Threat to Station

The International Space Station crew members did not need to take shelter in their Soyuz spacecraft when a piece of debris from a Chinese satellite made its closest pass by the station at 1:47 p.m. EDT today.

Mission Control gave the all-clear to the Expedition 24 crew at 12:45 p.m. EDT, after additional tracking information showed the debris would not come any closer than 5 miles (8 kilometers).

Robert Pearlman
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Posts: 29191
From: Houston, TX
Registered: Nov 1999

posted 04-05-2011 02:00 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA update (April 5, 2011)
Mission Control and Crew Monitor Orbital Debris

The Expedition 27 crew aboard the International Space Station and the team in Mission Control Houston are monitoring a piece of orbital debris that might pass close to the station later today.

There isn't enough time to steer the station out of the way, as was done last Friday for a different piece of debris, so if the probability of collision continues to remain in the "red" category, the crew will be asked to shelter inside the Soyuz TMA-20 that brought them up to the station in December. That spacecraft is currently docked with the Rassvet module.

The piece of debris is from the defunct Chinese FENGYUN 1C satellite, and flight controllers have been monitoring it since early this morning.

There is an imaginary box drawn around the station that measures a half a mile deep by 15 miles across by 15 miles long (.75 x 25 x 25 kilometers), and if a piece of orbital debris is going to cross within that, the flight team is notified and begins computing a probability of collision.

The last several tracking runs have shown a "red" probability, so they notified the crew at 6:01 a..m. CDT today that they are tracking it and that the crew would need to begin the shelter procedures if it remains on track.

As of now, the debris is expected to pass about 4.5 km away from the station.

The time of closest approach is at 3:21 p.m. today, and the crew will start working the procedures about 1.5 hours ahead of time. They will remove the ventilation between the hatches and will close the U.S. hatches completely.

They will also configure all the communications channels to make sure they stay in touch with Houston and Moscow and will then crawl inside the Soyuz about 10-15 minutes ahead of the time of closest approach (TCA).

They will stay inside until about 15 minutes after the debris passes.

Mission Control will continue to track the debris, and if the probability lessens and moves to either a "yellow" or "green" category, the crew will not have to shelter in the Soyuz.

Robert Pearlman
Editor

Posts: 29191
From: Houston, TX
Registered: Nov 1999

posted 04-05-2011 02:45 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA update (April 5, 2011)
Space Debris No Threat to Station

Tracking data now indicates that a piece of orbital debris being monitored by Mission Control Houston will not pass close enough to the International Space Station to warrant the Expedition 27 crew members taking safe haven within their Soyuz TMA-20 spacecraft.

Mission Control gave the crew the all-clear at 1:41 p.m. CDT as the space station orbited 220 miles above eastern Asia.

Robert Pearlman
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From: Houston, TX
Registered: Nov 1999

posted 06-28-2011 03:40 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
ISS On-Orbit Status (June 28, 2011)
Last night at about 5:00 p.m. CDT, NASA Houston FTC (Flight Control Team) received notification of an upcoming "red threshold" conjunction of the ISS with a piece of orbital debris (Object 82618, UNKNOWN), with a TCA (Time of Closest Approach) this morning at 7:08 a.m. CDT — which was too late to begin planning for a DAM (Debris Avoidance Maneuver).

Therefore, FTC and crew made preparations for crew sheltering in Soyuz TMA-21 (26S) and TMA-02M (27S). PC (Probability of Collision) at last tracking fix (6:20 a.m.) remained in the Red box, at about 0.003, with a miss distance of 0.25 km radial, 0.375 km downtrack, 0.570 m crosstrack.

The necessary reconfiguration procedures (USOS [U.S. Operating Segment] hatches closed, etc.) began 1.5 hrs before TCA (5:38 a.m. CDT), and the six crew members ingressed their Soyuz vehicles.

At 7:08 a.m. the object cleared the ISS with no impact, and shortly thereafter the crew was given the Go for returning to the ISS.

[The late notification occurred because of the high air resistance (drag) of the object (about 175 times higher than ISS) which made its trajectory very sensitive to small errors in atmospheric density predictions at the current solar flux. Due to the high drag, there is no chance of a recurrence of Object 82618).]

According to NASA, this was the closest approach (about 820 feet) of a piece of debris to the space station to date.

Jay Chladek
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Posts: 2264
From: Bellevue, NE, USA
Registered: Aug 2007

posted 06-28-2011 06:57 PM     Click Here to See the Profile for Jay Chladek   Click Here to Email Jay Chladek     Edit/Delete Message   Reply w/Quote
Man, that is about close enough to read the number plate!

Robert Pearlman
Editor

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From: Houston, TX
Registered: Nov 1999

posted 03-17-2014 09:15 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA release
Station Debris Avoidance Maneuver Conducted

Playing it conservatively, space station flight controllers conducted a Pre-Determined Debris Avoidance Maneuver (PDAM) Sunday (March 15) at 9:37 p.m. EDT (0137 GMT March 16) to provide a healthy margin of clearance from the projected path of a piece of Russian METEOR 2-5 satellite debris that was calculated earlier in the day to approach the neighborhood of the International Space Station. The Russian satellite was launched in late October 1979.

The 7-minute, 9-second PDAM maneuver, which was coordinated throughout the day between NASA and Russian flight controllers, used the ISS Progress 54 [M-22M] thrusters from the Pirs Docking Compartment for an increase of one-half statute mile in the station’s altitude. Ballistics officers determined that a fragment of unknown size from the satellite would have made its closest approach to the station around midnight Eastern time, passing within about 1900 feet of the ISS at its radial distance, with an overall miss distance between the debris and the ISS estimated at about 10.5 statute miles.

The avoidance maneuver was the first conducted by the ISS since October 31, 2012. The three-man crew, which was notified of the possibility of a maneuver on Sunday, was asleep at the time of the reboost and was never in any danger.

The maneuver had no impact on space station operations nor will it have any effect on the orbital trajectory of the space station for the upcoming single-day launch and docking of the Soyuz TMA-12M spacecraft and the Expedition 39/40 crew that will liftoff from the Baikonur Cosmodrome in Kazakhstan on March 26, Kazakh time for a six-month mission on the complex.

p51
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Posts: 979
From: Olympia, WA, USA
Registered: Sep 2011

posted 03-17-2014 03:26 PM     Click Here to See the Profile for p51   Click Here to Email p51     Edit/Delete Message   Reply w/Quote
The three-man crew, which was notified of the possibility of a maneuver on Sunday, was asleep at the time of the reboost and was never in any danger.
WOW, asleep during the time? Sounds like they weren't even made aware it was going to happen. It's not like this occurs every day, you'd think at least the commander would want to be awake when this happened...

Kite
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From: Northampton UK
Registered: Nov 2009

posted 03-17-2014 04:52 PM     Click Here to See the Profile for Kite     Edit/Delete Message   Reply w/Quote
I was thinking exactly the same!

Robert Pearlman
Editor

Posts: 29191
From: Houston, TX
Registered: Nov 1999

posted 03-17-2014 04:57 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
On any other day, the crew may have wanted to be awake for the maneuver, but that same evening they had taken part in Channel 4's two-hour "Live from Space" special. It was their second time producing the same show in a week (having two nights earlier done the same for National Geographic), so it's not unthinkable that all they wanted to do was go to sleep afterwards.

Jim Behling
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Posts: 653
From: Cape Canaveral, FL
Registered: Mar 2010

posted 03-17-2014 07:10 PM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by p51:
...you'd think at least the commander would want to be awake when this happened.
Why? ISS is flown from the ground and the crew is just there for maintenance and experiment support. There is nothing that the commander would do any different asleep or awake.

Robert Pearlman
Editor

Posts: 29191
From: Houston, TX
Registered: Nov 1999

posted 03-17-2014 07:53 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
While everything Jim says is true*, if you talk to the astronauts who have been aboard during re-boosts and debris avoidance maneuvers, they generally do desire and enjoy the opportunity to experience the move.

* With the exception of the crew being "just there for maintenance and experiment support" — they are also there to experience spaceflight and extend humanity into orbit. Hence, it shouldn't be that surprising if they want to be awake for a maneuver, or for the same reasons, asleep after a long day.

All times are CT (US)

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