Talk:Space debris

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)

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)

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).

what is the three types of space junk?jm anthony(ucc)

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

$a=-{\frac {0.5\rho _{atm}v^{2}AC_{d}}{\rho V}}$

So if we assume that A is proportional to $r^{2}$ and V is proportional to $r^{3}$, then we get:

$a=-{\frac {0.5\rho _{atm}v^{2}C_{d}}{\rho r}}$

Where $\rho _{atm}$ is the atmospheric density and $\rho$ 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)

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

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)

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)

2006 "near hit" of Latin American Jumbo Jet

"In 2006, wreckage from a Russian spy satellite passed dangerously close to a Latin American Airbus carrying 270 passengers, reentering over the Pacific Ocean which is considered among the safest places in the world to bring down satellites due to its unpopulated vastness."

From what I read the point of view of the pilots made them think it was much closer... Enough so that they had to preform evasive maneuvers when in actuality it was some hundred km away. Should we make some note to this effect? Cs302b (talk) 10:23, 10 December 2008 (UTC)

Why should not write about space debris in fiction?

For example, there is a whole article about Space Shuttle in fiction. Such information, whether useful or not, surely adds some fun. Becides, how do you know if it is useful for others or not? 217.77.54.52 (talk) 08:23, 12 February 2009 (UTC)

See Wikipedia:Trivia sections. The only criteria for inclusion is whether the information is encyclopedic. Fun is irrelevant. -Loren (talk) 22:02, 13 February 2009 (UTC)

Fine thanks! I just have read these recommendations about trivia, and the first phrase there is "Trivia sections should not simply be removed from articles in all cases"!
P.S. "Fun is irrelevant"? That's pain in the neck :-) 78.37.47.108 (talk) 07:04, 17 February 2009 (UTC)

Collisional cascading

There ought to be a section on Collisional Cascading instead of the somewhat miss-named Kessler Syndrome link. The proper reference is abstracted at ADS:

http://adsabs.harvard.edu/abs/1991AdSpR..11...63K

--aajacksoniv 15:48, 17 February 2009 (UTC) —Preceding unsigned comment added by Aajacksoniv (talk • contribs)

organizing sections

I tried to put things in the right order. I moved Gabbard diagrams section to within Tracking section. I am not sure if it belongs in Measurement section, but at least it fixes the white space problem that existed before.

I put creation and impact events under Incidents section. If anyone wants to monkey around with this layout, please be my guest.--Anna Frodesiak (talk) 06:11, 13 March 2009 (UTC)

Section on cleaning up debris?

Shouldn't there be a section on this article covering the clean up of space debris?--Hontogaichiban (talk) 03:00, 13 August 2009 (UTC)

If there are sources about it, sure!--Knulclunk (talk) 13:04, 13 August 2009 (UTC)

crebit?

The article includes the word "crebit". Is there such a thing, or is that a typo? Matthew C. Clarke 07:28, 26 September 2009 (UTC)

Kosmos or Cosmos?

In a paragraph that mentioned Kosmos-1275, the term "Cosmos" is also used. Should they all be the same, or are Kosmos and Cosmos distinct things? Matthew C. Clarke 07:55, 26 September 2009 (UTC)

More use of bullets?

I find this article hard to read because it just keep going and going with example after example. Sometimes I think "didn't I read this example a couple of paragraphs back?" I think it would be more easily scanned, and hence more comprehensible, if there were more bulletted lists. Do you agree or disagree? Matthew C. Clarke 08:15, 26 September 2009 (UTC)

Lists are generally detested by reviewers, but in this case I think that's not the real problem, it's the repetition? If that's the case, would you mind looking for examples where the same examples are really close together - like a couple of paragraphs? Also note that they might be repeated so they can talk about different aspects of the same event. But if this isn't the case, cleanup will improve things. I fixed the two you noted above. Maury Markowitz (talk) 12:05, 8 October 2009 (UTC)

Thanks. I'll re-read it soon to rethink the flow. There is a lot of really good stuff in this article, but I just think it is very dry reading. Matthew C. Clarke 09:58, 10 October 2009 (UTC)

Copy editing

Maury Markowitz has asked me to pop in and do a bit of copy editing for this article. If I have any questions with respect to content or context, or suggestions that will significantly alter the format of the article, I will leave them here. Thanks for the opportunity to pitch in, this is a very interesting subject and I can see a lot of work has gone into this article. Risker (talk) 23:09, 10 October 2009 (UTC)

Micrometeoroid or micrometeorite

I note that the second paragraph of the lede spells it "micrometeorite" as of today (Oct 2009). However, I believe "micrometeoroid" is correct. But before ruffling any feathers if, perhaps, the "...ite" term has become common vernacular terminology for outer space (extraterrestrial) usage, thought I should bring it up here first. What do others think? Cheers, N2e (talk) 21:32, 15 October 2009 (UTC)

Standard definitions:

micrometeorite--an extraterrestrial particle, less than a millimeter in size, that has survived entry into the atmosphere without melting.

micrometeoroid--(astronomy),(geology) an extraterrestrial particle less than a millimeter in size.

Micrometeoroids are NOT Space Debris

The section on micrometeoroids should be moved to a different article. According to the definition (all man-made objects that...) they are not space debris. Some parts in the section (dealing with protection) may, however, be of interest here. Agree? --Mikeo (talk) 19:17, 3 December 2009 (UTC)

Yes I agree. Most of that material would work just as well in Micrometeorites#Effect on spacecraft operations. The section on asteroids is not particularly relevant either. It's good material; just somewhat off topic.—RJH (talk) 23:30, 15 December 2009 (UTC)

Any data on distribution of number vs mass?

It seems clear that the massive objects are the most problematic in that they have the most potential to feed an exponential runaway of collisions. Therefore, in considering active mitigations, it might be useful to have plots of the distribution of number of objects vs mass, both total and for the subset of massive objects passing thought the critical region between ~500 km and ~2000 km. Of course eliminating junk over, say, 100 kg, does not diminish the hazard of 1 kg objects colliding with 50 kg objects, which is still serious because of the large number of smaller objects, but it might limit the magnitude of a potential catastrophic runaway before the situation becomes completely hopeless. Has anyone studied the energetics of the traveling salesman problem for an ion drive tug to go around in LEO and collect the larger objects? I expect this is not a promising approach, yet anything we can do now to ameliorate the problem, even partially, could pay large dividends later on. Wwheaton (talk) 21:08, 6 December 2009 (UTC)

There have been studies for ion-drive tugs bringing objects from GEO to a graveyard orbit above GEO (performed i.e. for ESA). There were also some studies about the issue of bringing larger objects from higher LEO (above 900 km) to graveyard orbits some hundred kilometers above (I've seen those ideas presented on a conference - I don't know which.). Basically you have to avoid any significant cross-plane maneuver to save fuel, and try to re-orbit objects in similar orbits. However, as of today, there would be noone paying for such an effort. Threre is no business case - at the moment - to do that. To your first question: Hugh Lewis of University of Southampton is dealing with the question which objects' removal would have the biggest effect on the future development of the debris environment. There have been several publications made by him. Mikeo (talk) 20:32, 7 December 2009 (UTC)

Lunar dust

The following paragraph was noted for being out of context with the remainder of the section, and I have to agree.

In the 1960s a new concern surfaced. In 1957 Hans Pettersson conducted one of the first direct measurements of the fall of space dust on the Earth, estimating it to be 14,300,000 tons per year. If this were true, then the Moon would be covered to a very great depth as there are limited forms of erosion to remove this material. In 1961 Arthur C. Clarke popularized this possibility in his novel A Fall of Moondust. This was cause for some concern among the groups attempting to land on the Moon, so a series of new studies followed to better characterize the issue. This included the launch of several spacecraft designed to directly measure the micrometeorite flux (Pegasus satellite program) or directly measure the dust on the surface of the Moon (Surveyor Program). These showed that the flux was much lower than earlier estimates, around 10,000 to 20,000 tons per year, and that the surface of the Moon is relatively rocky.

I was bold and removed it from the article. Where do you think it should be placed? Thanks.—RJH (talk) 23:28, 14 December 2009 (UTC)

I copied this paragraph to the Micrometeoroid article.—RJH (talk) 23:50, 15 December 2009 (UTC)

Ummm, Pegasus was specifically built to measure the threat to Apollo spacecraft from meteors. I think that's extremely on-topic in the context of the historical development. I'm re-adding a different version that should make this more clear. Maury Markowitz (talk) 12:35, 2 September 2010 (UTC)

Catcher's Mitt

Just a heads up, I have started and article about Catcher's Mitt, DARPA's recently announced debris mitigation study. -SidewinderX (talk) 21:17, 15 December 2009 (UTC)

Transhab

I have moved this section here from the original article:

Later designs for protection from small space debris and micrometeroids included the multi-layer inflatable shell of NASA's TransHab space habitation module. This soft ballistic shield technology was subsequently licensed by Bigelow Aerospace, which is pursuing extensions to this technology for a private space station design—having launched two inflatable-technology, non-habitable spacecraft, Genesis I in 2006 and Genesis II in 2007. Template:As of, both spacecraft were still operating nominally after more than 10,000 orbits and traveling over 270 million miles each.

Transhab uses a multi-shell design, but not for the reasons suggested in this paragraph. The idea is that each layer supports only part of the load of the one within it, so no one layer has to support the entire load. This means that each individual layer can be thin, and thus retain its flexibility. This, in turn, makes it easy to inflate. In contrast, if the inflatable structure is made out of a single layer of material with the same physical strength as the multiple layers combined, then the resulting structure would be quite stiff and difficult to inflate. It is true that this structure also offers additional safety in terms of puncture, but that is not the design criterion.

I think the text can be savaged, however. If it is, it needs to be in the proper section. It was placed in the history area, and should be located much further down in the article, where designs are being considered.

Maury Markowitz (talk) 19:45, 31 August 2010 (UTC)

After reading it a few times, I definitely think this should go back in. The question is where... the history section is definitely not appropriate, but at the same time, none of the sections below seem exactly tailored to it. BTW there was considerable work on this for the various space colony efforts in the 70's we should track down too. Maury Markowitz (talk) 12:30, 2 September 2010 (UTC)

New category for derelict manmade objects orbiting Earth

A new article category has been created, Category:Derelict satellites orbiting Earth. Please add the category tag to any Wikipedia articles on derelict satellites, spacecraft and spent upper stages that are orbiting Earth, as you run into such articles from time to time.

The category was created in February 2011 as a result of a discussion on Wikipedia:WikiProject Spaceflight; discussion is here.

The idea was to create a category that would include derelict satellites that are still in orbit, and thus a challenge or potential problem for other Earth-orbiting satellites, as they use up some of the common resource space "real estate" and thus create externalities for others who are attempting to utilize space, especially near-Earth orbital space. Of course, some of those negative externalities are the various problems discussed here in the Space debris article.

If anyone has a systematic way of locating articles on these Earth-orbiting derelicts, please have at getting them categorized appropriately. Cheers. N2e (talk) 22:33, 13 February 2011 (UTC)

Speed of debris in relation to other debris and new missions.

I am not sure, but I believe all rockets launch in the same direction as the earth is orbiting. If that is the case, is not all the debris traveling at roughly the same speed and direction? - The same speed and direction as all satellites and spacecraft? The article does not help me gain an idea of the speed debris will be travelling at relative to its victim, when it impacts operational space craft and satellites, and why does that speed difference exist.??? It's something I have always wanted to know, but nobody ever mentions it. (----) —Preceding unsigned comment added by 77.103.10.148 (talk) 15:09, 23 February 2011 (UTC)

No, this is not true. Although most debris orbits in the same direction as the earth (it takes less energy to launch them that way) the orbital inclinations vary quite widely. It is easy to put something into a 28 deg inclination orbit from Cape Canaveral, or a polar orbit from Vandenberg, but other orbit inclinations are obtainable by a plane change after launch. The bottom line is that debris is going in nearly all directions and speeds.

Even if all the debris were going at the same speed in a 28 deg inclination orbit, collisions would occur at high relative velocities because a satellite might be crossing the equator going north while the debris might be crossing the equator going south. It all has to do with the orbital planes, which would still vary with the time of the launch.Rocket Laser Man (talk) 19:58, 24 May 2011 (UTC)

Laser Broom

Reference 119, which itself is not well-written, has been misinterpreted, and there is a confusion between laser ablation and photon momentum.

The formation of a "working mass" to slow down space debris is misleading if not totally wrong. The laser ablation technique slows down the debris by using Newton's Third Law of Motion of equal and opposite reaction. As the gas ablates off the debris, it shoots off ahead of the debris, causing a recoil on the debris itself, slowing it down. This also is misleading, because the debris will actually spiral down, speeding up in velocity. However, this may get too complicated for this type of article.

The photon pressure technique reviewed in reference 119 is a desperation attempt. If you can't get enough laser power on the debris to evaporate any material, then you still might push it with photon momentum. The trouble is, photon momentun is terribly small, and it would take powerful lasers operating for long periods of time. This is not practical for many reasons. The debris moves at 6000 meters per second, and doesn't stay in range very long. Secondly, you can't go shooting powerful lasers through the sky in big arcs because there are other satellites and airplanes to worry about.

The paragraph as written here, makes none of this clear and the result is to mislead the reader into thinking that such an approach has promise. A delta v of 1 mm/sec is less than the uncertainty in atmospheric drag due to changing solar activity.

It seems that the photon momentum approach should be clearly distinguished from the laser ablation approach. The delta V quoted seems to apply to the laser ablation approach which is incorrect: it actually is intended to apply to the photon momentum approach. For example is a Lawrence Livermore Report that talks of laser ablation delta v thousands of times larger than the 1 mm/sec quoted for the photon momentum technique. Clean up of this paragraph seems desirable. Rocket Laser Man (talk) 19:48, 24 May 2011 (UTC)

Post-FAC Review

Following the FAC, I was asked to generate a list of issues that I thought would need to be addressed in order to pass FAC. In the interest of article improvement, I've listed them below. Certainly not everybody will agree with my perspective, but please try not to take these remarks personally; I'm just trying to be objective.

Post-FAC article review by RJH

• Per MOS:DASH, the article needs to be consistently using either a spaced en-dash or an unspaced em-dash in sentences. Currently it is using a curious mixture of dashes and spacing arrangements.

  "...orbit as a result - not just the satellites..."

  "...to a worrying possibility – instead of the density..."

  "...into their launch vehicle—robotic capture, navigation..."

  "...substantial additional fuel—to be able..."

  "...number from 8,500 to 13,000 - compare pg. 6..."

I used simple dashes for everything.

• Likewise, the page ranges should use an unspaced en-dash.

  "pp. 340 - 341"

Done.

• Units should be written consistency. The article lists: "0.04 inches (1.0 mm) per second", "650 feet (200 m)" and "24”x24”x12”". See WP:UNITS.

Done.

• There are many statements where WP:DATED applies. Examples:

  "is currently within five years"

  "Recently the University of Madrid..."

  "The ISO is also in the process..."

All done.

• The content contains many unnecessary additive terms, such as 'also' and 'another'. These should be purged.

Done.

• For references such as "Kessler 1971", I would normally recommend using the sfn template. However, since you are not using the standard citation templates, this won't work unless you use the equivalent HTML coding.
• Some of the wording is highly emotive, which makes it read as PoV-ish. For example: "feared", "China suffered", "Particularly worrying", and "leads to a worrying possibility". WP:NPOV may apply here.

Done and done.

History

Micrometeorites

• "This early work, in collaboration with Fletcher Watson, led the Harvard Observatory to build a station observatory...": The statement about collaboration with Fletcher Watson appears ambiguous. Is he collaborating with Helmut Landsberg, Fred Whipple, both, or with the Harvard Observatory? Or is he doing similar work?

Fixed.

Kessler's asteroid study

• Regarding the use of the "Kessler 1971" reference, I looked through the paper and it doesn't appear to say anything to the effect that "transiting the asteroid belt would not be particularly risky". Instead, it says how much shielding would be needed for specific risk levels. Hence, I don't think that reference is being used appropriately. Perhaps there is a later Kessler reference that would work?

I am waiting Don's email. In the meantime I have re-writted this section.

Follow-up studies

• "Similar studies continue to this day." Cite please.

They are all through the article. Instead of providing a list, I re-wrote this.

• "To everyone's surprise...": Everybody? Or just the investigators?

Removed.

A new Kessler Syndrome

• This section begins with "During the same period". This is vague because the previous section discusses measurements made until the present day. It would be better to give a specific year.
• "...lower than their rate of decay...": The meaning of this statement is unclear. Is the intent to convey '...lower than their rate of orbital decay...'? Likewise for "...greater than decay rates...".
• "...where additional debris can quickly upset the system...": What 'system' is becoming "upset"? Does it mean 'upset the equilibrium'? The word 'upset' seems too anthropomorphic.
• "...that quickly reduces...": 'quickly' appears to be unnecessary vagueness.

All fixed.

Debris growth

• "...by moving the boosters away from their payload...": In the design or after reaching orbit?
• "The population growth has...": I know that new spacecraft are being launched, but isn't this describing the increasing estimate of the number objects remaining in orbit? I.e. is the increase because of more objects being launched or better tracking? The above wording implies the former.
• "...debate within the community...": What community?
• "Others have pointed out...": see WP:WEASEL.
• "...the environment would continue to contain the then-known population until about 2055, at which point it would increase on its own." This doesn't quite make sense. Why would the equilibrium change in 2055?
• "...begin some time around 2015..." 'some time' seems redundantly redundant with 'around'.

All fixed.

Characterization

Large vs. small

• "In terms of numbers,": The article is already discussing numbers. I assume this means 'quantities'. Why not simply: "The vast quantity of debris consists of smaller objects,..."?
• "...the vast bulk..." uses 'bulk' ambiguously. It can mean size, mass, or quantity.
• "...estimates that debris items smaller ... probably exceeds". The text has already said this is a guess, so either 'estimates' or 'probably' is redundant.
• "...much lower..." and "...as a considerable proportion..." are vague.

All fixed.

• "As debris mass tends to be dominated by larger objects, most of which have long ago been detected, the total mass has remained relatively constant in spite of the addition of many smaller objects.": This would only be true if no new launches were made.

No, only if new launches were not offset by new decays. Because of the debris mitigation techniques mentioned further down in the article, decay rates compared to launch rates have changed.

• "Using the older figure of 8,500 known debris items, the total mass is estimated at 5,500 tonnes." The dating on this estimate is completely uncertain.

I disagree, as it is mentioned earlier, but I have changed this anyway.

Debris in LEO

• "Any impact between two objects of sizeable mass spalls off shrapnel debris from the force of collision" is a sentence fragment. I'd suggest 'can spall off' or 'always spalls off', although I think the first is more accurate.

Hmmm, ok.

Debris at higher altitudes

• "Olympus was hit by a meteor..." 'Olympus' is redlinked, so this statement is unclear. Perhaps "The EAS telecommunications satellite Olympus was hit by a meteor..."

Fixed.

Sources of debris

Dead spacecraft

• The first paragraph, while interesting, seems like trivia. Is there anything that will tie this into the remainder of the section?

Removed, although I prefer introductory leads in any long sections.

• "As radar returns fall off with the fourth power of distance, in order to obtain useful returns the satellites were powered with a BES-5 nuclear reactor in order to provide enough energy to the broadcaster.": I think the statement about the radar return is not needed here, and is straying off topic. To be pertinent, all it needs to convey is that the spacecraft were powered by BES-5 nuclear reactors.
• The last sentence needs to be tied into the topic, or else it is trivia. It is also redundant with some content in the "Threat to unmanned spacecraft" section.

Boosters

• The last sentence of the second paragraph (CBERS-1/SACI-1) belongs with the examples in the third paragraph.
• "...countries did not follow suit for some time." is vague and needs a citation.
• "...A third break-up event also occurred...": the 'also' is unnecessary here; it already states that this is the third event.

All fixed.

Debris from and as a weapon

• "...largest single space debris incident...": Largest in terms of mass or of quantity?
• "...most densely populated part of space...": I'd clarify that 'population' here specifically refers to satellites. Also, some use of the word 'orbit' might be better than 'space'.
• "...and they had decayed by early 2008.": The missile was launched in early 2008, so this doesn't tell the reader much. Also, debris is singular, so it should be 'this' rather than 'they'.
• "...cause enormous damage to the LEO environment": The environment is a vacuum; I don't think it can be damaged.

All fixed. I disagree with the last point, "the environment" is everything in LEO, including satellites.

Operational aspects

• Both paragraphs need referencing.

Removed, as above.

Threat to unmanned spacecraft

• "panels tend not to produce new debris as much as a cloud of gas-sized particles that does not present as much of a risk to other spacecraft" This doesn't quite make sense. Does it mean: "panels tend to produce a cloud of gas-sized particles that, compared to debris, does not present as much of a risk to other spacecraft"?
• "In a Kessler Syndrome cascade..." This paragraph is not cited.

Fixed and Fixed.

Threat to manned spacecraft

• The discussion of the risk to the shuttle in this section seems to need a reorganization. It doesn't flow very naturally and seems to meander back and forth. Please take a look at how this could be improved. Also, since STS-135 was the final shuttle mission, the tense of the section should reflect this.
• "At one point these..." needs a year.
• "The damage due to smaller debris has now grown to become a significant threat in its own right." Does this mean the 'rate' of damage? Or has the damage itself somehow become more dangerous?
• "Chipping of the windows became common..." needs a date.

Minor stuff fixed, but I don't see the problem with the flow. Suggestions?

Hazard on Earth

• This section just lists a series of examples of stuff falling harmlessly to the ground, which conflicts with the section title. I think it needs some reworking, reorganization and/or a better focus on the risk factors.
• "The Columbia disaster in 2003 demonstrated this risk," The risk was mentioned three paragraphs earlier, with two harmless impacts placed in between.

So and so? I really don't see either of these as problems.

Tracking and measurement

Tracking from the ground

• "Radar and optical detectors such as lasers..." A laser is not a detector.
• "NASA Orbital Debris Observatory..." This sentence seems like a trivia note. Can it be placed in context? What is the benefit of the liquid mirror?
• "...maintains a catalogue containing..." Past tense, 'that contained'.
• "Nevertheless, the majority of debris objects remain unobserved." If you can't observe them, then how do you know? Is this based upon debris models?

Fixed and fixed.

Measurement in space

• "...Mir Environmental Effects Payload which studied the enviornment in the Mir area" I don't think that payloads study anything; 'measured' perhaps. Also 'enviornment' => 'environment'.
• "...debris hardware is also a valuable source..." Unnecessary 'also'.
• "The close examination of its surfaces allowed the analysis of the directional distribution and the composition of debris flux." The use of 'the' articles seems odd here. Perhaps:

  "Close examination of its surfaces allowed an analysis of the directional distribution and composition of the debris flux."

• "...could provide additional insight." Is this being planned? If so, when and by whom?
• "...to provide another means for validating...": an unnecessary 'another'.
• "...Mir were also extensively studied...": an unnecessary 'also'.

All fixed.

Gabbard diagrams

• "The distribution of the resulting diagram..." It's nit-picking, but I think it should say it is the plotted data that have the distributions, rather than the diagram.

Ok.

Dealing with debris

• Doesn't this paragraph belong in the 'Debris growth' section?

Fixed, I don't know who added this.

Growth mitigation

• I think the sentence "The previously mentioned change ... debris characterization essentially eliminated..." needs a re-write. The word 'characterization' is too... well, bureaucratic, and the sentence contains ambiguities. For example:

  "The modification of the Delta boosters, at a time when the debris problem was first becoming apparent, essentially eliminated their further contribution to the orbiting debris."

• "...launch license regime to Earth orbits." Please clarify what 'regime' means in this context. A rule perhaps? If so, why not say rule? This seems especially

unclear given the varied use of 'regime' elsewhere in the article.

• "The ISO is also in the process" needs a date and uses an unnecessary additive term 'also'.

All fixed.

Self-removal

• "It is already an ITU..." => "It is an ITU...".
• "Another proposed solution..." additive => "A spacecraft can be launched with an electrodynamic tether attached."
• "At the end of their lifetime..." ==> "At the end of its lifetime...".

Fixed.

External removal

* "...cannot be removed under its own power" makes no sense.

It should now.

• "large spacecraft capture and hazard mitigation" is ambiguous. Does it mean "capture and hazard mitigation of large spacecraft" or "capture and hazard mitigation using large spacecraft"?
• The first use of "laser brooms" is unlinked. It also remains unexplained until the third paragraph. Is this sentence even needed? Or is it redundant?
• Does "SIS vehicle includes the vehicle capability" need to use "vehicle" twice?
• "Another potential solution is the laser broom, which uses...": additive term => "The laser broom is a potential solution that uses..."
• "Recent NASA research (2011)" is awkward. It uses a dated term then gives the actual date in parentheses. How about "NASA research in 2011"?
• "Another well-studied solution...": additive => "A well-studied solution..."
• "US Air Force worked on a ground-based design" When? It should state in the first sentence that this design was for a "laser-broom".
• I think "New approaches involving multi-use, ... regime to Earth orbits" needs to be re-written. It sounds like an advertisement and uses unclear jargon. It also appears to repeat part of the third paragraph of the "Growth mitigation" section.
• The math notation ">2 kg" should be written out => "more than 2 kg".
• "...announced that it has won..." has => had.
• "New upper stage rockets are being designed..." by whom?

I believe all of these are fixed.

References

• The FAC folks are fairly fastidious about wanting the citations to have a consistent appearance. This means all author names should be listed in the same form and with the same punctuation. Unfortunately, there is a lot of variance here that needs to be stamped out.
• Please include doi and/or bibcode links for the journal articles. For example: The Collision Probability of Geostationary Satellites.
• What is the "Orbital debris" reference?

Done, except the doi. I'm not sure about that last one, is it still a problem?

Okay, that's it for now. Regards, RJH (talk) 21:16, 13 July 2011 (UTC)

That is a very helpful review of the article RJHall; your specifics on what needs improved will be very helpful to any editor who wants to comprehensively work at improving Wikipedia coverage of this topic. Cheers;. N2e (talk) 22:32, 13 July 2011 (UTC)

Thank you, I was glad to help. Good luck with the article and I hope you bring it back for another FAC cycle. Regards, RJH (talk) 14:40, 14 July 2011 (UTC)

All changes implemented with the exception of the formatting of refs. Is there a tool for this? Maury Markowitz (talk) 16:18, 14 July 2011 (UTC)

I'm not aware of one, but it would certainly be helpful. All I can suggest is trying the various {{Citation}} templates. Some people don't like to use those, but I find them to be very helpful in maintaining citation consistency. For organizing citations, you might also look at WP:LDR and {{sfn}}. Thanks. Regards, RJH (talk) 16:27, 16 July 2011 (UTC)

Mmm, sorry but I don't agree that these have all been addressed. In addition,

• The Whipple (2000) citation does not verify that, "some variety of the Whipple shield has been almost universal for decades". It only confirms that it is widely used in 2000.
• The sentence that begins "Similar studies were applied to Jupiter's moons..." is off topic and leads to some ambiguity at the start of the next paragraph. I think it can be removed without harming the article.
• Something is messed up with the sentence that begins, "firing a laser beam at a piece of space junk". It looks like it has a space indent. -- fixed
• I think you can link the citations to the bibliography as per the following example:

  In the reference:

  <ref name=k9165>[[#bib_kessler_1991|Kessler 1991]], p. 65.</ref>

  In the bibliography:

  {{refbegin}}

  <ul>

  <li id="bib_kessler_1991">Donald Kessler (Kessler 1971), ...</li>

  ...

  </ul>

  ...

Regards, RJH (talk) 19:37, 19 July 2011 (UTC)

I have addressed these additional points, except the linking which I will not do, and moved/reformatted N2E's additions. Maury Markowitz (talk) 02:55, 21 July 2011 (UTC)

The missing sentence

User:Maury_Markowitz reverted this contribution from another editor without any explanation. I reverted it with the comment: "why remove the sentence? It's in the BBC's article." . He revert it again with the comment: "Re-removing sentence - that the author in question thinks his idea is great doesn't make it great, and especially worth quoting POV just because he stated it" and for reason better clear to himself, decided to write me on my talk page instead here. As I explained User:Maury_Markowitz, the sentence is actually not from the author of the proposal, but from a third party.

Now I do think that the sentence is important firstly because the feasibility in technology and costs is in my opinion a fundamental subject and secondly because introduce the political and strategic issue that I think has not been treated in the article. If someone feels that the text of the sentence is too close to the one from BBC, please feel free to modify it. --Dia^ (talk) 18:22, 23 August 2011 (UTC)

Note that Dia added the statement again, complete with broken reference, in spite of no consensus being reached on this issue. I'll re-state my concern: the quote in question makes POV claims about the validity of a paper project. The quote was clearly taken from the first "space person" the BBC could find, in this case a remote-sensing company better known for amateur radio efforts. Why the article needs this POV statement is a mystery to me, which is why I deleted it, re-formatted it, and fixed the reference. As to the "political and strategic issue", that's not part of the quote being discussed. Maury Markowitz (talk) 12:42, 24 August 2011 (UTC)

Thanks again! I find you extremely amusing! (and no, is not ironic)

To come to your concerns:

• you said the link is broken - wrong - actually works perfectly fine, I just checked it one more time. You just added the date and title, I don't have anything against it.
• you feel that the comment from a third party reported by the BBC's journalist is POV because "The quote was clearly taken from the first "space person" the BBC could find". Your statement is clearly NPOV, right? (yes, here I'm ironic) To make such an allegation you need at least a reliable source for it. Just for the sake of it, here some info on the guy and here some more giving the opinion. (I'd say wrong again)
• You didn't "re-format the statement" -wrong - you just deleted a sentence that I reinstated.
• You said: "As to the "political and strategic issue", that's not part of the quote being discussed." - wrong - The second part of the sentence you removed reads: "even though the political implications of taking out a functioning satellite could make the plan a non-starter." I agree with you, the subject is just fleeting treated. In the BBC article is a bit more detailed. In my opinion, it should be expanded since is a big issue. If you don't feel that the political implication, or rather the sensitivities of some governments and companies is an important issue, that state why.--Dia^ (talk) 13:33, 24 August 2011 (UTC)

Please allow me to make an observation regarding the aforementioned edit. To me, the opinion that "The scheme has been commended for being far more practical than the average proposal..." fails WP:WEASEL and is a bit dubious in it's use of the word "average". It would be better to list the actual quote with the source. For example: Italian Space Agency researcher Marco Castronuovo says that, "People have come up with all sorts of daft ideas... that are really science fiction at the moment. Something like this is a lot more practical." Regards, RJH (talk) 14:47, 24 August 2011 (UTC)

I don't have anything against to quote or even change the wording, only the sentence should read "Mr Stuart Eves said that people have come up with all sorts of daft ideas... that are really science fiction at the moment. Something like this is a lot more practical." For ease of use, here the cited BBC's article. I still think that the important bit is the following sentence, this from Mr. Castronuovo: "This kind of approach could be seen as a threat to operative systems; if you have the power to go to an object in space and pull it down, nothing prevents you from going to an operative satellite and pulling it down, so it's really a delicate matter." At the moment the two paragraphs are summed up in a short one on this article. --Dia^ (talk) 16:51, 24 August 2011 (UTC)

When the removal of a single weasel quote generates this much hostility, I think it's safe to say it should go. I'm going to modify the section and fix the reference. If the quote is added again I will remove it and invite you to start a formal process before adding it again. Maury Markowitz (talk) 13:39, 3 September 2011 (UTC)

Actually, I just summarized all the non-mainstream solutions into a single statement. Maury Markowitz (talk) 13:46, 3 September 2011 (UTC)

Sources to consider for inclusion

found items which have not been incorporated but might help content

• {{#invoke:citation/CS1|citation

|CitationClass=citation }}

• --User:Ceyockey (talk to me) 19:17, 19 February 2012 (UTC)

Another Speed Question

What's the maximum average speed (well, ignore outliers) of space debris? Any impacts would result in objects traveling slower, correct? Or would a big object making a small piece of shrapnel make the shrapnel travel even faster than the net of the two velocities? Speed and mass are going to (roughly) determine the amount of damage that can be done... It's also implied in a number of articles that small stuff traveling fast turns into plasma upon contact - how fast does that need to be? How much space inbetween layers of shielding are needed to dissipate the energy of the plasma?
~ender 2012-03-27 8:29:AM MST — Preceding unsigned comment added by 98.165.52.42 (talk)

Reference 7 Creation Ex-Nihilo Technical Journal

I do not want to open a can of worms, but... The paper cited in claiming 10 - 20 kilotons per year of meteoric dust is from what appears to be a magazine that is "less than main-stream". The journal is now called the "Journal of Creation" and is most likely a rag with fake peer review by a religiously motivated group. (This is my opinion) Just because they said it, doesn't make it wrong, but I suggest we remove the citation and find a better one. The journal's web site is headlined as being "Creation Ministries International". The April 22, 2012 article "Creation and evolution: teaching two histories",according to the web site "It’s about teaching opposing histories of the world, and (where possible) showing how biblical creation is overall the one that best fits reality." What is wikipedia's policy on technical content? Can any published opinion be used as a source of valid technical content? If so, Wikipedia is doomed.71.31.149.105 (talk) 01:45, 25 April 2012 (UTC)

Excellent new article on space debris legal issues

There is a pretty comprehensive new article on space debris legal issues here: Legal issues surrounding space debris remediation, Michael Listner, The Space Review, 6 August 2012. Could definitely help us beef up the (undercovered) legal and political side of space debris in the article. Cheers. N2e (talk) 17:20, 8 August 2012 (UTC)