ISS crew throws out space junk?

[bdewoody]

I was surprised to read that the crew of the ISS actually tossed some old un-needed hardware from the space station. Are they sure it will re-enter and burn or will it will become more orbital junk to dodge? <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[jimfromnsf]

It will reenter in less than a year

 

[henryhallam]

The two items thrown out were both relatively large, which makes them easy to track and avoid, and were thrown retrograde so they will reenter relatively quickly. They are also in quite a low orbit, below the majority of satellites. So they're not much of a collision hazard compared to, e.g. the recent Chinese ASAT test which produced lots of small pieces of debris over a wide spread of low to high orbits.

 

[barky]

I'd like to know how well they'll be able to narrow down the impact area, how far in advance we'd be notified, and the chances of it being a populated area. I'm sure NASA made those calculations, but I haven't seen it published.

 

[MeteorWayne]

These are relatively small objects.<br />They are large enough they might show up on the upcoming reentries, but I doubt it.<br /><br />See the observing spacecraft thread in Missions And Launches for a link.<br /><br />Any any case, no need to notify anyone. You can't make any calculations that far in advance since it all depends on the density profile of the atmosphere, which changes all the time. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

I haven't even had time to look yet. I'm guessing it's weeks or months away anyhow, Waist deep in Meteor Stuff right now <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[barky]

Would it have been too hard to attach a remote controlled rocket to boost it to a safe area if necessary?

 

[usn_skwerl]

watching the video, it looked to me like he released it in a tangent AWAY from earth...towards a higher orbit...how's this gonna affect its reentery overall, even if it is retrograde? <div class="Discussion_UserSignature"> </div>

 

[barky]

Based on a couple of the posts in this thread, it sounds like it's too soon to know whether the ammonia tank will land in a populated area, so we don't know whether a remote controlled rocket would help. Anyway, a certain percentage of the planet is populated so we could determine the odds of space junk hitting a populated area. The more we know about where, the more accurate we could be, but the odds can currently be calculated. I wish the media reported them.

 

[jimfromnsf]

1. It is not known whether if any of the hardware will survive entry. If any, it will be small pieces<br /><br />2. remote controlled rocket would help and give a precise reentry. But there are issues: a. there is no room on the shuttle missions to bring one up. b. There isn't an existing design. c. There are safety implications with bringing up a rocket on the shuttle and with the astronauts dealing with it. d. The cost of such a rocket would be too much for the little benefit<br /><br />3 The odds are too high to calculate The reentry of the object is affected by the current density and height of the atmosphere and its shape. The tank is not an aerodynamic shape and therefore unpredictable even when it does reenter. Also because this, the heating environment is hard to predict.

 

[jimfromnsf]

there can't be a tangent away from earth. A tangent is parallel to a point on the surface. Retrograde is opposite of the velocity vector which is tangential to a circular orbit.<br />A higher orbit can only be achieved by going posigrade

 

[usn_skwerl]

i was referring to this video, if you let it load, and slide the "needle" towards the rightover the first two minutes or so, youll see the solar panel rotating, which doesnt look fisheyed or warped in the camera perspective. as you see the arm rock, and the tank drift away, it definitely appears to head away from earth.<br /> <br />http://video.google.com/videoplay?docid=-6091676085108157978 <br /><br />and jim, seriously. kill the jackassery. i didnt mean a literal tangent...christ. i dont need a lesson in trigonometry. is "vector" more fitting for you? <img src="/images/icons/rolleyes.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[barky]

According to the article ISS Crew to Toss Space Junk on Spacewalk, "NASA officials said each object will be tracked for roughly a year, at which point they'll mostly burn up the Earth's atmosphere-except for sizeable chunks of the ammonia tank." So we can assume at least one chunk will hit the Earth. Let's be optimistic and say <i>only</i> one chunk. If we know nothing at all about the density of the atmosphere or anything about where it will land, then the chance that it will land in a populated area equals the percentage of the earth that's populated. I don't know what percentage that it, but it seems it would be too high to make it worth the risk. Most of us earth people would probably appreciate knowing the odds to the best of the experts' ability to calculate them, and I bet we'd think it's worth the extra cost and the decreased amount of science that could be done to keep us safer.

 

[jimfromnsf]

"kill the jackassery"<br /><br />???? It wasn't meant that way. I was just providing a little lesson in orbital mechanics. But in the end with your snide remark, maybe you are due for a refresher in trig. If you didn't mean " literal tangent", what did you mean?

 

[jimfromnsf]

"I don't know what percentage that it, but it seems it would be too high to make it worth the risk."<br /><br />????<br /><br />It isn't too high. You have more risks in your daily, that you have no control of either, like getting hit by a plane.<br /><br /> NASA doesn't do this without regard to safety on the ground. NASA calculated the before they went on with this task. Per NASA guidelines:<br /><br />"The guideline for uncontrolled reentry provides an upper limit of 8 m2 on the total casualty area of debris that impacts the Earth. An upper limit of 8 m2 is derived by assuming an average risk of human casualty of 0.0001 per reentry event. However, the risk of a reentry event causing any casualties is actually lower since no correction has been made for the fact that people are usually protected inside buildings or vehicles and will therefore be shielded from reentering debris. To date, no casualties have been attributed to reentering man-made space structures."<br /><br /><br /><br /><br /><br />

 

[barky]

Maybe I'm nitpicking, but I don't think Guidelines and Assessment Procedures for Limiting Orbital Debris, which is where the Rational for Guideline that Jim posted comes from, are binding rules. It mentions a debris assessment report. I wonder if one has been made for the "reentry event" we're discussing.<br /><br />I just skimmed this article, where lead flight director Bob Dempsey says "We have looked at the risk of that and we believe it's reasonable. ... We will try to provide as much information as possible about the timing and the location of where that re-entry will occur. It likely would be over water, but ... it's too hard to predict exactly at this point."

 

[jimfromnsf]

It is binding.

 

[henryhallam]

More than 50 meteorites of >100 grams reach the surface of the Earth every day. Other satellites reenter on a regular basis, many with components that make it through the atmosphere. There is no recorded instance of anyone being injured by either meteorite or space debris, though a meteorite did crush a parked car several decades ago.

 

[MeteorWayne]

It was found to be manmade, not a meteorite.<br />I have a followup article around here somehwhere...<br /><br />{Wayne disappears into a dusty back room piled high with data...will he ever return?} <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

It didn't really crush the car, rather punched a massive hole in the rear panel. Image attched, the metorite is visible at the very right rear, behind the car.<br /><br /><br /><br /> video link <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[bdewoody]

I was basically thinking that this action would potentially be a source of bad PR for NASA. Knowing how reporters can spin relatively harmless activity into a mega disaster I don't think it was such a good idea at least in the current anti-manned space flight atmosphere. <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[MeteorWayne]

Satellites and rocket bodies come back to earth all the time.<br />It's really no big deal <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[3488]

Hi MeteorWayne.<br /><br />Was the case you illustrated, cause a big row with the insurance company, went to court<br />& the car owner won?<br /><br />The insurance used the crappy 'act of god' excuse for not paying out.<br /><br />As you say, the Earth is forever being pelted by natural objects & perhaps less frequently by<br />man made ones.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[MeteorWayne]

newsartist,<br /><br />OK, I checked.<br /><br />I don't have any reason to believe it was a hoax (the NJ meteorite).<br />Something definately punctured the house, and the preliminary analysis was that it was an Iron-Nickel meteorite.<br /><br />There was a followup article that stated it was later determined from metalurgical testing, that it was a man-made substance, with no other details.<br /><br />I sent an inquiry to the AMNH which did the testing for more information, but never received a reply.<br /><br />I will follow up, to see if I can find out more. Thanx for the reminder.<br /><br />MW <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[jimfromnsf]

It was a piece of metal from a wood chipper