Talk:Space debris

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[edit] Burned Cottage?

I'm too new to delete anything, but the discussion of a cottage being burned down by a bolide (= meteorite) has nothing to do with space debris. There is NO assertion that the bolide was debris. Hence I suggest deleting it. A3burke 22:44, 22 August 2007 (UTC)

[edit] Planetoids.

What about the terms planetoid and planetesimal? Where do they fit into the schema? --Dante Alighieri 09:10 13 Jul 2003 (UTC)

Planetoid appears to be synonymous with asteroid, and planetisimals aren't around any more since they formed into planets. I'll mention them, though. Bryan

Does anyone really call planets "debris"? -- Oliver P. 10:39 13 Jul 2003 (UTC)

I just wanted to make sure all objects were included. I wouldn't be surprised if some astronomers consider them as such, though; in astronomical terms, "metal" is any element heavier than helium. :) Do you think this article should perhaps have a different title? Bryan
I'd definitely like a different title. When I saw "space debris" I expected a discussion of burned-out rocket stages, lost bolts, and such that humans have scattered in nearby space. Not a list of all matter smaller than stars. Vicki Rosenzweig 16:43 13 Jul 2003 (UTC)
How about "solar system objects"? Solar system has a list with that title that seems to cover somewhat similar turf, though in a different way (it lists all large moons by name, for example). "Space debris" could then become an article about the artificial junk in Earth orbit. Bryan
This page is excellent. How about incorporating it directly into solar system, high up in the article somewhere? If you are worried about length of article, I would suggest punting the list of large moons into a separate article: this schema is more informative -- hike395
That works for me. Natural satellite already has a table that lists all moons categorized by size category along one axis and planet along the other axis, so the list of moons in solar system is actually somewhat redundant and inferior; I think the list can simply be deleted. Bryan

When the article says "paint chips," does it mean so literally? --NeuronExMachina 05:23, 11 Aug 2004 (UTC)

Absolutely. Even a paint flake can cause major damage at orbital speeds (up to 11 km/s) ··gracefool |☺ 07:37, 7 Jun 2005 (UTC)

[edit] Lost glove

Does anyone know the story of how that glove got lost? I'm curious too. Wadsworth 03:56, 19 October 2005 (UTC)

In 1965, during the first american space walk, the Gemini 4 astronaut Edward White, lost a glove. For a month, the glove stayed on orbit with a speed of 28,000 km / h, becoming the most dangerous garment in history Mr_mattyp 17:53, 26 February 2006 (GMT)

[edit] Monitoring Space Debris. How advanced are things?

This paper suggests that out of the estimated 150,000 objects in orbit around earth, NASA is only able to track about 15,000 of them at an accuracy of over 10m. It also says "This appears to present a very significant challenge. However with appropriate technology extensions, laser ranging can meet this requirement." So it appears if they can monitor all of that if the appropriate equipment. I am going ask some questions over on another wikipedia discussion board to see where this is at today.

Does anyone here know what the current stats are and if they actually monitor space all the time. Can they detect anything that would suddenly occur. Say debris splitting into 2 parts? Thanks. (Simonapro 19:51, 29 July 2006 (UTC))

Currently, approximately 13,000 objects are constantly monitored by the US Space Surveillance System. Out of these, only orbit data for about 9,800 of these objects is publicly available. The smallest objects in the catalogue are about 6 cm in diameter, tracked by the Cobra Dane Phased Array on Shemya Island. The lower threshold of the catalogue depends on the object orbits and their effective radar cross sections. Therefore, in GEO, the minimum size for catalogue objects is about 1 m. The latest space debris environment models (i.e. MASTER-2005 by the European Space Agency) predict that slightly more than 600,000 objects larger than 1 cm, and 150 Million Objects larger than 1 mm are currently orbiting the earth. Only sporadic observations of objects below the catalogue threshold are possible. They are used to validate models of the space debris environment like MASTER. Your second question: Yes, such events have been observed. Due to the catalogue threshold this has only been possible for objects large enough. Mikeo 09:25, 30 July 2006 (UTC)

That is great. Thanks for that update. I guess one question on a lot of people's minds is if this kind of monitoring can actually detect UFOs? Would the current operational monitoring actually detect a UFO entering the atmosphere if such a craft did come from outer space or is the setup more geared towards checking space 'now and again' to see if the projected movements of the debris are as expected? Thanks again (Simonapro 09:49, 30 July 2006 (UTC))

That would all depend on whether or not a UFO was in the field-of-view of the sensor. A lot of debris is only tracked when it gets close to active spacecraft. The US Space Surveillance Network is heavily tasked, and thus updates to all the trackable debris is not something that can be done on a continuous basis. Another thing to consider is the types of tracking (or more correctly, detection in your question of UFOs) sensors. Radar, such as Cobra Dane can track small objects with reasonable range data, but relatively poor positional data when compared to optical sensors. Optical sensors have excellent positional (Az/El) data, but no range data (except via triangulation).


[edit] Size of debris

Currently, the article includes the sentance "Most of those unusual objects have re-entered the atmosphere of the Earth within weeks due to the orbits where they were released and their small sizes.". (Emphisis added; line unreferenced) This goes against everything I know of physics. Size should have no impact on orbital behavior, other than smaller sizes decrease drag against what little atmosphere is up at its altitude. Am I missing something, or can I just remove this item? Porkrind 03:06, 4 February 2007 (UTC)

Doesn't sound right to me either. Removing. -Loren 05:56, 4 February 2007 (UTC)
Too bad! it was right, let me explain : atmospheric drag is proportionnal to the size and decelerates the mass of the object. Thus, the effect of atmospheric drag is proportionnal to the surface/volume ratio, i.e. considering two objects of same shape and density, but of different sizes, the smaller will decelerate faster than the bigger. Is that clear ? Duckysmokton 15:47, 5 February 2007 (UTC)
If I understand you correctly you're saying that the acceleration on an object due to drag is given by
a = - \frac{0.5 \rho_{atm} v^2 A C_d}{\rho V}
So if we assume that A is proportional to r2 and V is proportional to r3, then we get:
a = - \frac{0.5 \rho_{atm} v^2 C_d}{\rho r}
Where ρatm is the atmospheric density and ρ is the density of the object. Correct? -Loren 01:31, 6 February 2007 (UTC)
Exactly, I didn't know the formula that you show, but the idea is here : A/V is porportionnal to 1/r, then object size have an effect on the almost-orbital behaviour (almost since inside the exosphere, objects don't orbit forever). Thanx for the revert, perhaps adding a <ref> to explain that point would avoid later misunderstanding ? Duckysmokton 12:21, 6 February 2007 (UTC)
Sounds good, thanks for bringing this up. Guess I should have thought a bit more carefully before changing things, my physical intuition must be going out of whack. -Loren 15:54, 6 February 2007 (UTC)
At least its gotten worked out. I had no idea. Porkrind 03:39, 8 February 2007 (UTC)
To be totally anal about it it's actually ballistic coefficient that's important.WolfKeeper 03:51, 8 February 2007 (UTC)
Well, to be even more anal, it's basically the old relationship between inertia and an external force, good 'ol Newton's second law.-Loren 04:06, 8 February 2007 (UTC)
It is not Ballistic Coefficient, which measures something similar to Coefficient of Drag, it is the actual drag on the object. BC and Cd are variables that are applied to an object but do not account for size of the object by themselves. Size is much more important in a rarified area such as where things orbit the earth, Cd and BC start to become irrevelant. Reginhild 18:38, 18 May 2007 (UTC)

...objects in orbit around Earth created by humans that no longer serve any useful purpose...

I can think of lots of humans that no longer serve any useful purpose!

I have no idea what your maths equations mean, but spelling, grammar and punctuation are pretty important too. When I logged in, my intention was to suggest alternative wording for the introductory paragraph but now I'm too cowed by science to try.

Seavy carr 20:00, 7 May 2007 (UTC)

[edit] What about Mir?

Isn't a space debri example? why it isn't even mencioned on the article??? 200.233.133.203 11:06, 24 July 2007 (UTC)

It burned up during re-entry. If anything was discarded before re-entry please add the reference and info to the article. -- Jeandré, 2007-07-29t11:12z

[edit] Russian Spy Satellite v Latin American Airbus

What is the source for the item in the History section stating

In 2006, wreckage from a plummeting Russian spy satellite whizzed dangerously close to a Latin American Airbus carrying 270 passengers. ?

The NZ Herald 29 March 2007 printed news of a LAN Chile flight reporting seeing satellite debris five nautical miles in front of and behind the plane. Next day the story was that experts doubted the debris was from a Russian satellite and that NASA said the satellite reentered at the expected time 12 hours earlier.

See

http://www.nzherald.co.nz/section/story.cfm?c_id=82&objectid=10431449 http://www.nzherald.co.nz/section/story.cfm?c_id=82&objectid=10431624

Taringi (talk) 02:12, 5 February 2008 (UTC)

[edit] Tons or Tonnes?

Is the reference to tons supposed to be tonnes? If so can someone update the page. If it is infact tons can someone convert it to tonnes and remove the tons altogether. Imperial measurements should end at 99km, there is no need for such a primitive and senseless measurement system in relation to space. —Preceding unsigned comment added by 86.111.162.127 (talk) 20:53, 7 March 2008 (UTC)

LOL! By Wikipedia standard Units of measurement we should use tons. After all, it's mostly our crap that's up there, so we get to use our units. But seriously, go ahead and add the conversion after, in parenthesis. 100 tons = 91 tonnes. Have a blast. --Knulclunk (talk) 03:55, 8 March 2008 (UTC)