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Archive 1

January 2006

I've removed this page's entry from Wikipedia:Requested moves due to a lack of consensus on the move from Space Shuttle external tank to Space Shuttle External Tank. If this changes, feel free to add another request. --Lox (t,c) 22:09, 6 January 2006 (UTC)

Needs specifics on LH2/LOX ET capacity

A great article but a common question is how much LH2 and LOX does it hold -- by both weight and volume. Suggest you make a bulletized list, or a box with the main ET specificiations. Include ET diameter, length, dry weight, total wet weight, and individual LH2/LOX capacity by both weight and volume. That way readers can quickly see the essential physical characteristics. Joema 01:44, 8 January 2006 (UTC)

Liquid Hydrogen bias

The extra amount of 1.100 pound (500 kg) liquid hydrogen to prevent oxygen-rich cutoff seems questionable. NASA states a value of only 700 pound on http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/prop/et.html

--84.44.195.11 23:34, 17 March 2006 (UTC)

"ET thermal protection system" section updates

This section still mentions that the shuttle program is grounded, but obviously this isn't the case. The only reason I didn't update it myself is that I don't know what NASA did about the foam issue.--Erciesielski 21:47, 9 September 2006 (UTC)

Ares I Second Stage

The article currently reads, "Like the Solid Rocket Boosters, the ET will be used in the upcoming heavy-lift Ares V (CaLV) and man-rated Ares I (CLV)." This seems dubious: other description say the Ares I second stage will be a new design. What sources currently support the assertion that the Aries I second stage will be derived from the Shuttle external tank? Sdsds 01:03, 18 February 2007 (UTC)

Future use as baseline

The assertion that the ET will serve as the "baseline" for the Ares I second stage is totally befuddling. The two aren't even close to the same size! What verifiable source claims the ET is the baseline for the Ares I second stage? Sdsds 21:10, 11 March 2007 (UTC)

It's probably just confusion as the ET will be used as a "baseline" for the Ares V first stage. Pictures of the Ares I show a second stage that looks similar to an ET in color. When compared to the Ares V, it is obvious that the Ares I second stage is very small, but when taken alone, I can see how one would think it was a derivative of the ET. Anyways, it's a simple mistake; no need for hyperbole here. Cjosefy 14:22, 12 March 2007 (UTC)

Clarification of "Befuddling" remarks

If you take a look at the recent changes/additions to the area in question, I believe you'll all be in agreement with the clarifications made. WSpaceport 20:51, 23 March 2007 (UTC)

Yes this is now much, much better. Thank you! (sdsds - talk) 01:01, 7 June 2007 (UTC)

Standard US Usage

Some folks seem to be unclear on the appropriate usage of the term "Aluminum". Please see the wikipedia article aluminum for clarification. If this were an article about, say, British efforts to invent and perfect Radar, then referring to an aluminium antenna would be appropriate. This article however, is about the space shuttle, an endeavor unique to the United States, and therefore it is appropriate to maintain standard US usage, and refer to the aluminum/lithium alloy used in the super lightweight tank. When England starts a space program and launches a man to the moon, it will be entirely appropriate to refer to the aluminium used in the boosters. Thank you. Anastrophe 02:07, 22 June 2007 (UTC)

CFC-14?!?

It was claimed that the CFC used to blow the foam used as insulator was CFC-14. Anyone familiar with the number protocol for refrigerants knows that there can be no such thing; with four fluorine atoms, a methane is completely replaced and there won't be any chlorine, with four chlorines, there won't be any fluorines, hence, it won't be a CFC cause it doesn't have both! I've replaced it with CFC-11 based on http://spaceflight.nasa.gov/shuttle/rtf/otte/et_thermal_protection_fact_sheet.doc which mentions CFC-11 as well as HCFC 141b. Zaphraud (talk) 21:04, 9 December 2007 (UTC)

Emptying after a cancelled launch

Does anyone know what happens to a filled external tank if the launch is cancelled at the last minute? Can the liquid hydrogen and oxygen be pumped out again for cryogenic storage, or are they allowed to evaporate? I can't find an answer to this question anywhere.Christidy (talk) 02:23, 12 February 2008 (UTC)

Wet Workshop?

Is it worth mentioning the wet workshop proposals for the ET that were kicking around prior to the Challenger accident? The only reason the ET doesn't end up in orbit every mission is that it is deliberately de-orbited, and some people suggested using its large interior volume for part of a space station. Problem is, I've had trouble finding information on this, I'm purely going on memory here. Damburger 01:00, 24 December 2006 (UTC)

Yes this is an important idea that makes the ET a bit more exciting. The source you want is the Finney and Jones book Intersteller Migration and the Human Experience. There's a paper on using either the metal of the ET or its structure for a station. I believe its by the University of California Press. I will try to put the basic concept on the page.

>> I can't find a source to back this up, but my recollection from back when the Shuttle was being pitched as an idea was that the ET would be reused in orbit as the basis for a future space station. Clearly that never happened, and it seems like a waste to keep throwing them away every time. Anybody know why they didn't keep them up there? After 120+ missions, you could have built quite a large inter-connected structure out of those ETs. —Preceding unsigned comment added by 86.134.207.228 (talk) 14:59, 10 June 2008 (UTC)

The reason an ET hasn't been orbited yet is probably due to the lack of flight control systems on it. After the shuttle returned to Earth the ET could burn up accidentally unless it was fixed with thrusters on the mission. (81.132.150.208 16:21, 7 July 2007 (UTC))

It is mentioned that it is caused to de-orbit, how? If it doesn't have propulsion how is this controlled?
i.e. the ET must have orbital energy itself because the orbiters thrusters aren't powerful enough to give it the extra thrust (are they?)
So how do they control the ET's landing point if (for example) it is atmospheric resistance that de-orbits it.

  • The ET never enters into orbit, hence why no engines are needed. The space shuttle OMS burn gives the required thrust to put the shuttle into orbit. The ET falls back to earth in a ballistic trajectory to a pre-determined landing zone. There is no guidance system on the ET. Skiman14 —Preceding comment was added at 16:30, 31 October 2007 (UTC)

With regards to the wet workshop idea it is used at various points in fiction e.g. Kim Robinson's Mars Trilogy. Is this also worth a mention? Rufty 12:42, 24 October 2007 (UTC)

Reusing the External Tank

With the development of the "Soft Capture and Rendezvous System"(SCRS)for the Hubble Telescope repair mission(Astronauts will install a docking device for future controlled deorbit of the Hubble Telescope)should NASA attach a similar device on the ET (or future Ares rocket stages)so the Space Shuttle "could"? deliver it to the Internation Space Station (ISS), which is currently serviced by remotely controlled Russian Progress and European "Jules Verne" space tugs which would be used to "corral" the ET in safe nearby orbits. There are many good uses to recycling (60,000 lbs.)ET's- for spare parts,attach scientific experiments,storage space etc. Jalanp2 (talk) 22:30, 28 June 2008 (UTC)

Actually no, they researched this quite well before in the 80s. They are not safe for human operations, and as such cannot be used as modules. The only use an external tank has up there, is as material to be used for construction, but that would include welding operations, which have not been done in space so far and have many inherent problems. The conclusion was simple, the idea sounds fun, but in reality its just not practical. --TheDJ (talk • contribs) 23:53, 28 June 2008 (UTC)
The following link shows NASA's "Soft Capture and Rendezvous System" for a hypothetical use on the External Tank. http://www.nasa.gov/images/content/218655main_SCRS_FS_img1_lg.jpg Jalanp2 (talk) 23:00, 11 July 2008 (UTC)

Freon rumor

There is a rumor going around that the Columbia disaster was caused by NASA's decision to use HCFC 141b as a blowing agent instead of CFC-11 (freon) [1]. The story goes that the new blowing agent produces adhesion problems. However the report investigated this and found that ET-93, the external fuel tank that shed foam that damaged Columbia's wing, had been constructed using a closeout foam called BX-250, whose blowing agent was CFC-11. I have added a referenced note on this [2] so as to avoid misleading the reader and encouraging the false rumor. --TS 03:32, 3 August 2009 (UTC)

Under pressure

It seems a bit misleading, in the opening paragraph, to state that the ET provides the fuel and oxidizer under pressure. The SSME has two sets of turbopumps for each (fuel and oxidizer). Using oxidizer as an example, the LPOTP boosts the LOX pressure from 100 to 422 psia, at which point the HPOTP boosts it from 422 to 4,300 psi for injection into the reaction chamber. The 100 psi in the tank isn't really significant pressure compared to the 4,300 psi needed by the SSME.... Or am I missing something? (sdsds - talk) 00:55, 7 June 2007 (UTC)

Maybe the pressure prevents cavitation under intense pumping, or to prevent ET collapse.--Musaran (talk) 14:04, 28 September 2009 (UTC)

Cost and time please

The Super Lightweight Tank section says "The disadvantages of the SLWT are its increased cost (~$5 million) and production time (~4 months) when compared to the LWT." but doesn't give the cost or time of either type as a baseline. Can anyone provide ? Rod57 (talk) 12:12, 27 March 2010 (UTC)

I can only find that Lockheed Martin had a 2007 contract to build 17 external tanks (SWLT?) for $2.94 billion. (~$173 m each?) whereas In 2002 NASA extended a contract to get 35 SWLT for $1.5 billion. (~$43 m each?) Rod57 (talk) 12:12, 27 March 2010 (UTC)

Future use and legacy

The Space Shuttle and Space Shuttle Solid Rocket Booster articles contain sections about their future use/fate (e.g. Shuttles go to museums, SRBs to be utilized for the development of next rockets, etc.). Similarly the Saturn V and Saturn IB account for the fate of the build, but unused components of the rockets. I think we should do the same for the External Tanks - give a list of what STS-xxx mission used what SRB-xx/ET-xx combination, and give the current status of the unused ETs.

According to [3], [4], [5], [6] the situation is the following: STS-134 and STS-335/135 would utilize ET-122 (refurbished after Katrina damage, fully certified and flight-worthy) and ET-138 (the last completely finished ET); ET-94 (older version LWT) will be used for test/development of in-line Shuttle-Derived Launch Vehicle; ET-139 is at advanced stage of manufacturing; ET-140 and ET-141 are in early stages of manufacturing. Alinor (talk) 10:31, 19 September 2010 (UTC)

The current future use section is in-line with that of the SRB, Saturn V and Space Shuttle articles. To list every tank/SRB set used would be a lot. The only one that has that sort of list is the Saturn IB article. It can be done there as there were not a lot of them built and used. I don't think a list in the article is the wise way to go. Maybe a list on its own OK, but not in the article. You don't want to over do it and make it boring.--NavyBlue84 16:31, 19 September 2010 (UTC)
I don't suggest that ET-xx/SRB-xx are listed exactly here, but somewhere, maybe on each line of the List_of_Space_Shuttle_missions (as the orbiter names are given). Especially the SRB-xx is interesting as these are reusable (as the orbiters).
In the future use section here I suggest that we add a few sentences mentioning ET-94, ET-139 and maybe ET-140/141. Alinor (talk) 09:55, 4 October 2010 (UTC)

Requested move

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Space Shuttle external tank → Space Shuttle External Tank — Since the tank is called External Tank (ET), shouldn't this article be renamed to Space Shuttle External Tank? Or maybe External Tank? Rehman(+) 10:05, 15 October 2010 (UTC)

Actually NASA (in the above link) calls it "Space Shuttle External Tank", in the header itself. Even this article calls it "Space Shuttle External Tank (ET)"... Rehman(+) 14:13, 15 October 2010 (UTC)
The NASA link only uses capitals in the headline, where title case is not unexpected. In the prose it is clearly not capitalized. "External tank" is not a proper noun. Powers T 22:44, 15 October 2010 (UTC)
I still think this article should be moved to "Space Shuttle External Tank" or at least "External Tank". ET is capitalized quite often ([7], [8], [9], [10], etc). Rehman(+) 02:28, 16 October 2010 (UTC)
Yes, especially since the Space Launch System (evolved from the Space Transportation System) envisioned in the new NASA bill is "standard rocket" (no spaceplane with rocket motors) - it won't have "external tank" - just stage I and stage II. So, in the next 10-20 years there will be no other "external tank" (assuming that NASA will stick to SLS and no "spaceplane with rocket motors" is made by foreign countries), there are no other external tanks in the past (soviet Buran Energia launcher is "standard rocket" with motors in the core stage) thus the article here becomes description of the External Tank. Alinor (talk) 05:50, 16 October 2010 (UTC)
The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

External tank disposal

We ought to have a section that details how the external tank breaks up and is destroyed after nominal separation to ensure downrange safety, especially since the SRB article has a complete detailing of its typical recovery protocol. For example, I know they leave some of the fuel in both tanks (it doesn't separate totally empty), so upon re-entry the heat causes the fuel to evaporate, expand and burst the tanks, allowing the resultant small pieces to burn up more readily. --Kitch (Talk : Contrib) 12:35, 23 September 2007 (UTC)

Is there any footage of the ET breaking up and falling into the ccean? I've only found this. [11] Night Tracks (talk) 04:43, 24 September 2009 (UTC)
Note that LWT ET reentry footage taken from Hawaii back in the 1980's motivated a program to study ullage pressure after ET separation in order to prevent burst. Film showed point of green flashing light (due to tank rotation) until a clear burst and cloud of debris appeared. Contractor testing to study leak vs. burst of 2219 AL sub scale pressurized 3 foot tall tanks done out west by Failure Analysis Associates around 1985(?) verified critical flaw length predictions. Burst of a separated External Tank would spread the debris foot print and was to be avoided in the interest of reducing the area of Indian Ocean needed for safe deorbit. —Preceding unsigned comment added by 198.179.229.37 (talk) 15:12, 26 January 2011 (UTC)
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