Talk:Hubble Space Telescope

Which shuttle

It's a constant battle to keep the lede paragraph short and to the point. There is all sorts of stuff that is perfectly true, interesting to some folks, and could be added. However, the lede should contain *only* the points that are most important to the topic at hand, which is the Hubble space telescope.

Exactly which shuttle carried the Hubble into orbit is not particularly relevant to the telescope. A good test is "What would have changed had it been a different shuttle?" Very little, as far as I know. So it's perfectly fine to put in the article, but not in the lead paragraphs and particularly not in the first sentence.

As always, other opinions are welcome. LouScheffer (talk) 12:56, 19 November 2010 (UTC)

Somewhat similar rationale applies here as does Edwin Hubble's nationality in the previous talk section. Which Orbiter is not critical to summarizing what the HST is in the Lead. But it does not matter too much to me. -fnlayson (talk) 13:40, 19 November 2010 (UTC)

This is not a big deal in the article - indeed, one of the main charms of Wikipedia is that fanatics of all stripes add all sorts of interesting detail to topics you never heard of. However, the lead paragraph in particular should be a concise overview of the topic. From The Elements of Style#The Third Edition (1979) LouScheffer (talk) 14:05, 19 November 2010 (UTC)

“ Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. ”

I find it a bit ridiculous, IMO, to war over a single word that in no way dtracts from the article, but if you are going to remove the name of the shuttle, it is more precise (and concise) to change the sentence to a space shuttle rather than the space shuttle. The common phrase "The space shuttle" is a holdover from when the Columbia was the only space shuttle. Since there are multiple space shuttles, it is not appropriate to use wording implying there is only one. One would not say the cargo was brought over on the ship, they would either include the name of the ship, or change the sentence to the cago was brought over on a ship. Just my two bits ... LonelyBeacon (talk) 15:50, 19 November 2010 (UTC)

You are absolutely correct. That's how it used to read, and how it reads now. Thanks, LouScheffer (talk) 20:28, 19 November 2010 (UTC)

The argument about this is absolutely ludicrous. It is completely relevant which space shuttle and mission carried the most well-known space telescope in all of human history to where it is. This information should absolutely be in the opening paragraph. But I'm not going to argue with editors who are on a power-trip to be dictators on Wikipedia. G90025 (talk) 13:40, 14 December 2013 (UTC)

Here's a crude calculation of what an extra word costs. This page is viewed about 70K times per month (see stats). Assuming everyone reads the first sentence, and they read about 200 words per minute, that's about 2 work-weeks of wasted time per year, or perhaps $1000 US of wasted time. This calculation is rather inexact, requiring many dubious assumptions, but point remains - we should be concise, especially in the lead... LouScheffer (talk) 20:41, 19 November 2010 (UTC)

I would never argue against having a concise leadin for many reasons (ranging from consensus and policy to aesthetics). Bringing up the economic argument might equally play into the reason it should be there: when people read the leadin, they expect something like that to be there, and now need to go look for it. I personally think it belongs, but if I was asked to defend it with policy or guideline, I would be hard pressed to find something. There are other things in the leadin that I would take out as not being necessary for a fundamental understanding of what the HST is, rather than the name of the shuttle that carried it into orbit ... but I must acknowledge that as an opinion, and nothing more than that. LonelyBeacon (talk) 03:20, 20 November 2010 (UTC)

Spurious stat - the time all the world's 6.8 billion people take over their daily dump accrues to centuries a day... but so what, it doesn't for EACH! We might as well all try to breathe a few times less each minute, "because it takes time we could be using for something else." Like, erm, taking a dump perhaps? Trevor H. (UK) 19:18, 4 October 2011 (UTC) — Preceding unsigned comment added by Trevor H. (talk • contribs)

The word negligible comes to mind. That aside, if we took up that position then nothing would ever get written. Fortunately we aren't paying per word and Wikipedia is not paper. For balance, please could you provide an estimate of the time wasted by people who do want to know which Shuttle it was launched by having to search for that information, and the time wasted compiling these statistics. --W. D. Graham 18:33, 25 June 2014 (UTC)

In a speed reading comprehension test, you just know that if the shuttle is named, it will be asked, making it the slowest word in the sentence. In other contexts, a boring specificity is barely observed. The first time I read LoTR as a 12 year old (this was before Star Wars) I made it through all three volumes in short order without being firm in my mind that Sauron and Saruman were two different characters. No, I wasn't reading Arabic shorn of the vowel markings, but I might as well have been in my rush to find out what happens. In this instance, as for which shuttle, that's the kind of thing a military aircraft buff simply can't live without, while the rest of us barely perceive the significance. People read by metaphor far more than they realize: if you say "delivered by the Reading Railroad" you don't have to specify the locomotive. The Space Shuttle was, after all, a kind of abstract rail line. I think the real reason everyone stuck to the "the" shuttle is that the stairway to heaven was single occupancy. For the same reason we refer to "the tennis ball" as if those conspicuous auxiliary bulges in the tennis tights are anatomical. The cute ball girl hands the tennis stud "a ball" and then he pounds "the ball" over the net. When does it change? Badminton does not have shuttle girls, so I guess it's best as changed.—MaxEnt 12:28, 24 February 2012 (UTC)

I'd say that is is more to do with the fact that there were only five Shuttles (six including Enterprise), whereas there are many trains in the world. A case of the extraordinary rather than the mundane. --W. D. Graham 20:26, 25 June 2014 (UTC)

Every satellite/probe that has been launched aboard a Space Shuttle and has its own page on Wikipedia mentions which Shuttle it was launched from in its opening paragraph(s) with the exception of Magellan (See: 1, 2, 3. 4, 5, 6, 7, 8, and 9). If that information is relevant enough for those machines, I don't see how should be different for Hubble. -Martinman (talk) 20:44, 24 June 2014 (UTC)

I can see absolutely no reason not to put the Shuttle name in the lead. The argument of brevity is nonsensical since the change won't even increase the word count of the lead ("a Space Shuttle" to "Space Shuttle Discovery") - and if he's so concerned about time wasted then we can save a few milliseconds on the load time by taking out the ridiculous footnote that has been inserted to explain this. --W. D. Graham 18:33, 25 June 2014 (UTC)

Mentioned in the Lead is fine, but not in the first sentence. That would just make the first sentence overly long, imo. -Fnlayson (talk) 18:45, 25 June 2014 (UTC)

For getting it out of the first sentence, how about "The Hubble Space Telescope (HST) is a space telescope that was launched in 1990 and remains in operation. A 2.4-meter (7.9 ft) aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared spectra. The telescope, which is named after the astronomer Edwin Hubble, was deployed by the Space Shuttle Discovery during the STS-31 mission and has since been serviced by five other missions." (changes in bold)? --W. D. Graham 18:51, 25 June 2014 (UTC)

• I was looking at putting the launch info in a 2nd sentence like "The Hubble Space Telescope (HST) is a space telescope that has been in operation since 1990. It was carried into orbit by Space Shuttle Discovery on April 24, 1990." Your version seems better and fits in with existing text. And that footnote can be removed with a change like these. ;) -Fnlayson (talk) 19:24, 25 June 2014 (UTC)

Hubble "lessons learned"

There is probably a lot that could be written here. I will start off. Something that Hubble mission should have considered was an INDEPENDENT evaluation of the mirror and assembly. I mean FULLY independent, including new instrumentation to measure the optical quality of both the mirrors and the subsequent assembly. I do not subscribe to the argument that such requirements are untestable. I invite the readership to comment. --96.244.248.77 (talk) 03:08, 3 March 2011 (UTC)

While true, Congress denied NASA the money to make it possible. The failure to test was an effort to cut costs, & it bit them. TREKphiler ^{any time you're ready, Uhura} 03:30, 3 March 2011 (UTC)

Kodak and Itek proposed that each would make a mirror set, then each would test the other's mirrors. Their bid was more expensive, and rejected. This is covered in the article. LouScheffer (talk) 18:28, 3 March 2011 (UTC)

Yes, but the bid was much less expensive then the money PE got after all cost overruns they did. Further I read somewhere that the US Air Force offered NASA an end to end test of the complete telescope for free. NASA declined the offer. Some suspect that the mirror error was known but kept secret to give the shuttle a PR stunt. Want a nightmare lesson? Orion needs a mission and could reach JWST at L2 to repair it! — Preceding unsigned comment added by 84.172.177.13 (talk) 07:59, 27 May 2011 (UTC)

I visited PE while the mirror was being polished and was shown it. I was also shown a large vacuum chamber in the same area that was to house the complete assembly to test it. I was told by my host that NASA had not approved (or withdrew the money) to test the assembly, and PE was out the money to construct the chamber. More than anything else I am concerned that this fact does not seem to be in the record (that I have seen anyway.) I also saw the first casting at corning, it was cracked. It was in a stairway mounted on the wall above a landing. hope you can use this information.Ianhenderson007 (talk) 15:35, 26 September 2012 (UTC)

There is also another, indeed bigger "lessons learned" on HST - the total life cycle cost of keeping the mission going from the time the initial flaw(s) was (were) detected. Perhaps a new telescope might have been a cheaper than trying to keep both HST and the shuttle program going? The main article does not discuss the totality of HST failure. Sure there were benefits, but at what cost?? I know this is controversial, but I'm asking for some real money figures to be presented - show us the cost/benefit. Life cycle costs don't end quickly - HST is still flying at the present time! 71.10.145.225 (talk) 02:42, 13 December 2014 (UTC)

Root cause of gyro failures identified

Bad claim.

Engineers are confident that they have identified the root causes of the gyro failures, and the new models should be much more reliable.

I was curious, so I checked out the William Harwood citation, which actually states that engineers are confident that they have resolved the root cause of failures of the CU/SDF-A (control unit and science data formatter) and that they are confident the telescope can continue operating with not so many gyros as they would like.

I Googled for "Hubble improved gyros" and all I found was "An improved zero gyro safemode".—MaxEnt 11:35, 24 February 2012 (UTC)

The root cause was corrosion of the fine wires in the gyro, and fixed by purging with nitrogen. This is described in this ESA page on the gyros, which I added to the article. LouScheffer (talk) 00:20, 10 June 2012 (UTC)

Needs section on UV capabilities and results

Very hard to locate Hubbles relevance to UV astronomy. Could we have a section to summarise Hubbles UV capabilites, past and current, maybe for IR too. - Rod57 (talk) 09:58, 1 June 2012 (UTC)

• Looks like just the STIS 115–1030 nm and WFC3 200-1700 nm. But what results ?
• Intro says near-UV but according to Ultraviolet#Subtypes WFC3 also covers Middle-UV and STIS even covers some of Far-UV (to 115nm). - Rod57 (talk) 14:16, 28 June 2014 (UTC)

I would add that HST (and other NASA) imagery is often presented highly "colorized". HST does not process human eye spectrum the same - thus colorized. NASA is ripe with presenting both colorized and "artist conception" imagery. Beware that this is not scientific and also biased. NASA does not usually indicate that images are often "doctored".--71.10.145.225 (talk) 03:07, 13 December 2014 (UTC)

Hubble images usually document fairly well what went into their creation, though you sometimes have to read between the lines (for example, it may only indicate which wavelengths were combined to render a final product, but that should tell you that the image has been manipulated). Images from the various Mars rovers normally get very specific about modifications made and whether or not an image represents Earth or Mars lighting. If NASA limited their images to what the human eye could see, we'd be left with quite a bit of dull imagry. I can't begin to understand how you can say these images are "not scientific and also biased" when those same images represent data used by researchers in their studies. I have to believe you're trolling here. — Huntster (t @ c) 09:25, 14 December 2014 (UTC)

Successors, NRO-1

The successors section probably should be updated to reflect this NYT report. SaltyBoatr ^{get wet} 21:03, 4 June 2012 (UTC)

http://www.nytimes.com/2012/06/05/science/space/repurposed-telescope-may-explore-secrets-of-dark-energy.html

Orbit height

In the article: "Orbit height 559 km"

"The Hubble Space Telescope is a joint ESA/NASA project and was launched in 1990 by the Space Shuttle mission STS-31 into a low-Earth orbit 569 km above the ground." http://www.spacetelescope.org/about/general/fact_sheet/ — Preceding unsigned comment added by Dart Raiden (talk • contribs) 01:13, 8 June 2012 (UTC)

There is no single orbital height. It gradually decays, but was boosted by the shuttle repair missions. LouScheffer (talk) 11:54, 8 June 2012 (UTC)

Reference Checking

Endnote 49 is cited in reference to Hubble cost. It directs to the FAQ page for a space agency. At this location, there is no discussion of Hubble cost. This reference was either made in error, or the FAQ page has changed. 199.46.245.231 (talk) 17:53, 4 July 2012 (UTC)

OK, replaced with a more recent NASA document that explicitly refers to life cycle costs (LCC) as of 2010. LouScheffer (talk) 13:48, 4 September 2012 (UTC)

"Ground" vs "figured" ?

The three stages in converting a hunk of glass into a precision astronomical mirror are grinding, polishing, and finally, figuring.

The Allen Commission Report makes it clear that the error in the Hubble main mirror was created during the figuring stage.

The article refers to an error in the grinding six times, and to figuring five times.

I think the references to grinding errors should be changed to figuring errors.

Former ATM and now NitPicker769 (talk) 01:20, 3 October 2012 (UTC)

I agree that if you divide the manufacture into three steps, then the error was in the last step, figuring. However grinding is also the verb used for the whole process, as in the following paragraph from the Space Telescope Science Institute

Newton had given up on trying to grind non-spherical surfaces. He’d tried it in 1666, but the technology of the time wasn’t up to the challenge. A sphere is the easiest shape to grind. Non-spherical shapes are very difficult to grind. In fact, astronomers would have to wait until 1721 for John Hadley to grind the first non-spherical telescope mirror.

or from a book on the Hubble telescope

The HST made a disastrous debut. When first launched in April 1990, it had faulty vision because its primary light-gathering mirror had been inadvertently ground to the wrong shape.

As in these paragraph, especially to non-specialists, grinding refers to the whole process. Figuring, on the other hand, is likely to invoke images of computing with numbers. This has caused confusion before. Readers thought an error in figuring meant that a mathematically wrong prescription was computed, as opposed to the real case where the design was correct and the manufacture was bad. Overall, I'd imagine a large majority of readers are not familiar with the technical meaning of figuring when applied to mirrors.

So overall, I agree the error was in the figuring step. But I think 'ground to the wrong shape' and similar wordings are a better description for the large majority of readers, and so the references to 'ground' should remain. LouScheffer (talk) 13:48, 3 October 2012 (UTC)

I agree with LouScheffer, that was my interpretation too. To the layman the whole procedure is "grinding", and certainly even reliable sources refer to the whole process as grinding when written for a general audience such as the quotes above. That all being said we don't necessarily have to treat the readers like idiots, and considering its importance to the subject perhaps a short statement to explain the process more clearly than presented currently would be useful. ChiZeroOne (talk) 14:06, 3 October 2012 (UTC)

Since this is an encyclopedia (or aspires to be :) ), I'd sooner we call the error a figuring error & link to it. That way we are technically correct, we offer more information for the curious, & we offer an easy explanation for the confused or unfamiliar. (And I count myself among those who've never heard it called a figuring error before.) TREKphiler ^{any time you're ready, Uhura} 15:54, 3 October 2012 (UTC)

I guess I'm too close to the subject (ATM). I would never consider "grinding" as the name for the whole process, but then not everyone has a blacked out basement and a dozen different grades of silicon carbide. I think Trekphiler's suggestion of a link to "figuring" is a good solution. — Preceding unsigned comment added by NitPicker769 (talk • contribs) 17:31, 3 October 2012 (UTC)

The Hubble Failure report does not call it 'figuring', it calls it 'final polishing'. When they use 'figure' as a verb, they refer to the process as a whole, or the specific modification of a sphere to a parabola, which happened during all three stages (since the RvNC accounted for the non-spherical shape). Here are two typical sentences from the report:

The primary mirror was ground and polished to an approximate

shape, about 1 wavelength rms, using the RvNC for the test. This took place at Perkin-Elmer's facility in Wilton, Connecticut. The mirror was then transferred to P-E's Danbury facility, where the RNC was the test instrument for final polishing.

To remove the spherical aberration from this system, we need to figure, or

shape, the spherical mirror into a parabolic (aspheric) surface. To make the marginal rays cross the optical axis at the same focal point as the paraxial rays, the surface is figured into a parabola by removing material from the outer surfaces of the mirror, Figure C-l(b).

By this definition, 'figuring' happened during all of grinding, polishing, and final polishing phases. And this definition of 'figuring' is not technically correct, either, since in the Hubble they were trying to make the mirror a hyperboloid, not a paraboloid.

So if even the solidest of references is not clear on what 'figuring' is, perhaps we should follow the reference and state that the error happened in the 'final polishing phase'. LouScheffer (talk) 18:43, 3 October 2012 (UTC)

OK, tried the re-write, with link. See what you think and modify as you see fit... LouScheffer (talk) 19:01, 3 October 2012 (UTC)

As it now stands, you're very close to what I'd want. Just two issues: the number of null correctors in the first steps could be clearer (one each? two each? two total?), & the wording. (I'd use "final step (figuring") Otherwise, good to go. TREKphiler ^{any time you're ready, Uhura} 19:19, 3 October 2012 (UTC)

Looks fine to me, too.

On another note, could any reader think that the "edge of the mirror" means the part running from the front to the back? Would something like "from the face of the mirror near the edge" be clearer? Or am I just living up to my handle? NitPicker769 (talk) 21:00, 3 October 2012 (UTC)

♠No, you might have a valid point, there. Best make it clear what is & isn't being figured. Maybe add a note in a caption where the mounted mirror hides the back-to-front edge? Something like, "The finished mirror with figuring complete"?

♠Aside: I haven't read the whole page in awhile, so, is the reason they didn't test more carefully mentioned? As I understood it, they were trying to save money because NASA was penny-pinching... TREKphiler ^{any time you're ready, Uhura} 22:30, 3 October 2012 (UTC)

I changed the text to "the perimeter was too flat" which seems less ambiguous to me. Other opinions are welcome. (Also 'final polishing' to 'final polishing step', per suggestion above. LouScheffer (talk) 02:44, 4 October 2012 (UTC)

One more tiny quibble, now, I'm afraid. :( Was the error bang on the perimeter, or just toward the outer rim? As phrased, you may be leaving a misleading impression. (Yeah, this is getting really technifinicky...) TREKphiler ^{any time you're ready, Uhura} 02:52, 4 October 2012 (UTC)

Magdalena Ridge - did it use a mirror ground for Hubble?

From one reference: Bakker, E.J. and Westpfahl, D. and Loos, G. (2008). "Magdalena Ridge Observatory: the start-up of a new observatory" (PDF). Astronomical Telescopes and Instrumentation: Synergies Between Ground and Space. pp. 701615--701615. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help); Unknown parameter |organization= ignored (help)CS1 maint: multiple names: authors list (link)

In the 1970s several classified research projects in the US developed zero-gravity mirrors for space based applications. Among these was a 2.4meter (7.9-foot) mirror developed by ITEK Corp. of Lexington, MA (Fig. 5). This mirror was never launched into space and was later found to be in storage at the PERKIN ELMER facility in Danbury, CT. At that point in time the AFRL was the legal owner of the mirror and was paying a monthly fee to PERKIN ELMER for its storage there. Since there was no planned use for the mirror, AFRL was interested in the possibility of other possible uses or users for it.

Since the Hubble was never classified, and never owned by the Air Force Research lab, this supports a military program. Also, the Hubble switched to a 2.4 meter mirror precisely because the tooling already existed, so the same mirror size is not very strong evidence.

and from Gordon J. Pentland, Kerry Gonzales, Kevin Harris, Eileen V. Ryan, Elwood C. Downey (May 2006). "The Magdalena Ridge Observatory 2.4 m Telescope". Proc. SPIE 6267, Ground-based and Airborne Telescopes. doi:10.1117/12.669795. Retrieved 19 Jan 2013. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help)CS1 maint: multiple names: authors list (link)

This telescope utilizes a high quality primary mirror and cell from a now decommissioned military application.

On the other hand, the reference that was used to derive the Hubble origin is no longer accessible, and a web search of the title could not find it either.

Also, the Hubble failure report mentions a backup Kodak mirror, but not an Itek one. A NY Times article states that Kodak and Itek made a combined bid for mirror construction, but it was rejected.

So overall, it seems to me the mirror is not from a Hubble program. But of course there could be other sources and evidence... LouScheffer (talk) 21:35, 21 January 2013 (UTC)

You are right; I jumped the gun a bit there—the new source I cited (your first above) is insufficient on its own. I was relying on my still-fresh memory of the source I cited last year (the one which had since become a deadlink) to close the gap, and I shouldn't have. However, I did finally relocate that old source:

Magdalena Ridge Observatory (01 January 2008). 2.4m Observatory Technical Note (PDF) (Technical report). 1.6. p. 2. Retrieved January 21, 2013. {{cite tech report}}: Check date values in: |date= (help)

The primary mirror was built by Itek in the 80's as one of three to compete for the Hubble Space Telescope.

I would prefer more than once source, but this seems a sufficiently reliable one to establish its origin in relation to Hubble. That being said, perhaps it's merely a trivial mention in the scope of this article. Thoughts? Maralia (talk) 22:11, 21 January 2013 (UTC)

There's another line of evidence that this is not a Hubble mirror. The Magdelena Ridge telescope has a primary that is specified as f/2.03, where the Hubble mirror is f/2.3. So the mirrors are different shapes, and it could not have been a backup mirror for the Hubble. Also, the Magdelena Ridge total optical system is f/8.8, where Hubble is f/24, so they have (very) different secondaries as well. Of course, they could still have been part of the same development program, even if different mirrors. Also, the "One of three" comments seems odd, since both the NYT and the failure report say there was 1 backup mirror. Overall, I suspect the other two sources are more accurate. LouScheffer (talk) 23:14, 21 January 2013 (UTC)

Here's another source that says "one of three for Hubble", but also states the primary is f/2.03, which is not the Hubble specification. NESSI: the New Mexico Tech Extrasolar Spectroscopic Survey Instrument LouScheffer (talk) 23:22, 21 January 2013 (UTC)

One other point. The first paper has a picture of the Magdalena mirror. Both the Hubble mirror (and the backup) have large mounting bolts at 120 degree intervals around the circumference. The Magdalena mirror does not appear to have them. LouScheffer (talk) 03:30, 22 January 2013 (UTC)

I sent an email to Dr. Eileen Ryan, director of the observatory, asking the origin of the mirror. Let's see if she responds, and if so what she says... LouScheffer (talk) 04:16, 22 January 2013 (UTC)

Thanks—appreciate your following up on this. Maralia (talk) 05:35, 22 January 2013 (UTC)

Dr. Ryan cheerfully replied as follows: The mirror *was* originally part of a competition for the Hubble contract, even though it is not the same optically as the Hubble mirror (different prescription); after Itek was not picked for the Hubble, it became part of a classified Air Force project; when the Air Force project in turn was discontinued, it became available for MRO. She says that according to the Itek folks she worked with (they helped adapt the zero g mirror to ground use) they could not use their (classified) military expertise to bid for the Hubble mirror. They built this one as an unclassified example, though it supposedly looks a lot like the spy satellite mirrors. This makes sense since the specs (2.4m, f/8.9) are a better match for looking through the atmosphere than for use in an orbiting telescope, where the PE/Kodak numbers (2.4m, f/24) make more sense. LouScheffer (talk) 03:38, 23 January 2013 (UTC)

Fantastic to get such a quick and helpful response from her. Thanks again for taking the initiative. Maralia (talk) 15:59, 23 January 2013 (UTC)

So which is it?

In the introductory section, penultimate sentence of last paragraph:

"The telescope is now expected to function until at least 2013."

In the last sentence of Servicing Mission 4 section:

"The work accomplished during SM4 is expected to render the telescope fully functioning at least into the year 2014, and perhaps longer."

67.60.251.74 (talk) 10:53, 23 March 2013 (UTC)

Quality?

The last sentence of the 4th paragraph of the introduction: "The telescope was restored to its intended quality by a servicing mission in 1993." is extremely biased. Correction of the optical distortion does not return the telescope to the "quality" intended. Since when does a patched repair job restore quality? The quality was never there to be "restored" nor does "intended quality" have a clear meaning. I suggest that if the claim is: "The telescope's capabilities were corrected to design specification by repairs and additional equipment during a servicing mission in 1993." to use that or something similar.173.189.72.242 (talk) 16:19, 13 April 2013 (UTC)

The confusion, I think, is whether it is talking about the quality of the telescope (an abstract quantity with no clear measurement, as in "the Hubble is an mediocre/satisfactory/excellent telescope) or the quality of the images. The quality of the images are what is meant. These did indeed have an intended quality (90% of all collected light within 0.1 arcsec, IIRC.), and were "restored" in the sense that they had an intended quality, then did not, then did again. In principal these two meanings of quality could be different - you could have a bad quality telescope that hardly ever works, even if takes high quality images on the rare occasions it works correctly. However, the Hubble has high quality by almost any metric (it works well AND takes high quality pictures) so the sentence (in my opinion) is not misleading, especially since the details are explained later in the article. LouScheffer (talk) 01:18, 14 April 2013 (UTC)

Proposed automatic updating of orbital elements

I've proposed that this article be included in a trial involving using a bot to update orbital elements automatically on a fortnightly basis. I've started a discussion at WikiProject Spaceflight regarding this article and nine others, and would welcome some input from the users involved in maintaining the pages in question. --W. D. Graham 21:00, 24 July 2013 (UTC)

Fun "fact" about HST's orbit

I just realized:

• Hubble was released during STS-32. That mission had to retrieve the Long Duration Exposure Facility (LDEF). So the orbit of the LDEF determined the initial orbit of HST.
• LDEF in turn was released during STS-41-C. That mission had to service the "Solar Maximum Mission" (SolarMax) satellite. So the orbit of the LDEF (which lacked orbital manoeuvring capabilities) was determined by the orbit of the SolarMax satellite.

So the orbit of the broken SolarMax satellite (plus orbital decay of the LDEF) determined the initial orbit of HST.

(Though the initial orbit of the HST and the orbit of the retrieved LDEF were not identical, as the Shuttle released the HST into a different orbit. Similarly the LDEF was released into a different orbit than the captured SolarMax. Hence I write determined and not identical.)

(And BTW, this is not a well researched fact, and I may be wrong – but I thought I shared this in case anybody was interested to follow this up.) Tony Mach (talk) 10:36, 27 November 2013 (UTC)

Without research, I suspect this is a case of correlation and not causation. All three are in the highest-altitude orbit accessible to the shuttle, obtained by launching due east to get the greatest gain from earth rotation. Probably all three wanted the highest orbit they could get. LouScheffer (talk) 13:37, 27 November 2013 (UTC)

I was aware that the inclination of 28.5 is favourable for launches from Cape Canaveral and the Kennedy Space Center. However, there is more to orbital parameters than inclination (and height) – if an spacecraft is to rendezvous with another object in space, the orbital planes have to match at the time of launch. From Orbital plane (astronomy): "A launch vehicle's launch window is usually determined by the times when the target orbital plane intersects the launch site." Moving the orbital plane is very fuel intensive and practically feasible only for small corrections. So yes, the launch site in Florida determined the inclination (and yes, the Shuttle determined the height), but I am still convinced that it is factual to state that the orbital plane (at the time of release) – and hence "the orbit" – was determined by the chain stated above, as the planes had to be chosen to coincide. The problem is that this is at the moment original research by (and not very good at that). So, if anybody can back that up with proper sources, it would be a nice (but not very important) addition, IMHO. Tony Mach (talk) 14:09, 27 November 2013 (UTC)

Images 'beamed' to earth in black & white, each captured in red, green and blue

In the "Hubble data" / "Transmission to Earth" section we find the following sentence : "Images from Hubble are beamed to Earth in black & white, with each image being captured with red, green, and blue filters. Then these images are combined into one image by a Hubble imaging team, using a "Technicolor process".[131]".

This ranges from being misleading to false:

- The data captured by cameras on the HST is not "black & white" in any meaningful sense. Each exposure captures the intensity of light within particular bands of the electromagnetic spectrum, none of which the human eye and brain would perceive as "black & white". I find it misleading.

- While the filter wheels include (roughly) red, green and blue filters, it is rare for all three of those filters to be used for one observation. There are many other filters in use, near infrared or "hydrogen" filters being favourites. Much of the observations are not even performed through more than one or two filters.

- Much of the data is not combined into color pictures at all. When it is, I most definitively would not describe the process as having anything to do with "Technicolor", which is a trademark referring to very specific processes that have little to do with all the digital processing done for astronomic pictures and is probably not even a remotely familiar term to most people anymore.

I'm erasing that sentence, it would not be particularly relevant to that section if it was correct, anyway. 82.231.41.7 (talk) 20:22, 3 December 2013 (UTC)

The point that the Hubble takes monochrome images through different filters, which are combined to make color images, seems important enough to mention. I made it more technically correct; it's an open question where it should go, but I left it here for now. LouScheffer (talk) 04:13, 4 December 2013 (UTC)

"Hubble data" seemed like the right section, so I added a sub-section "color images". LouScheffer (talk) 04:22, 4 December 2013 (UTC)

Hubble Space Telescope captures shattering asteroid

Headine-1: Hubble Space Telescope captures shattering asteroid, at least 10 pieces seen in photos.

• http://www.foxnews.com/science/2014/03/07/hubble-captures-shattering-asteroid/?intcmp=features

QUOTE: “ The Hubble Space Telescope has captured the first pictures of a disintegrating asteroid. Asteroid P/2013 R3 was detected in September in the asteroid belt between the orbits of Mars and Jupiter. It appeared as a fuzzy object. Further observations by ground telescopes revealed three bodies. The Hubble telescope uncovered 10 objects, each with dusty tails. The four largest fragments are up to 656 feet across. Scientists say the asteroid began coming apart early last year. They theorize sunlight is slowing pulling the asteroid apart by increasing its rotation. A planetary scientist at the University of California, Los Angeles, David Jewitt, led the investigation. He says seeing the rock fall apart before our eyes is pretty amazing.The pictures were released Thursday.” — [Amazing picture], FYI, Charles Edwin Shipp (talk) 22:59, 7 March 2014 (UTC)

 Done — Seems to be in the article here already; nicely done; great series of pictures. (Search for P/2013). — Charles Edwin Shipp (talk) 23:09, 7 March 2014 (UTC)

mirror error

I remember reading at the time that when the mirror was finished at PE, an old time telescope maker tested it, and said, hey, it is off..Is this true, and if so is there an authoritative source ? — Preceding unsigned comment added by 50.195.10.169 (talk) 21:56, 2 May 2014 (UTC)

Answered? -- Charles Edwin Shipp (talk) 10:47, 14 November 2014 (UTC)

The mirror type used in Hubble (Ritchey–Chrétien telescope) cannot be tested by any of the really old-time techniques that a skilled amateur, or professional from the 1930s or so, might use. This is precisely why the Palomar telescope, from the 1940s and 50s, does not have the wide-field performance of later telescopes. They were very worried about schedule and cost, and did not want to try any "new" technology, and so used a parabolic (not hyperbolic) mirror which could be easily verified by techniques from the previous century. Now for the Hubble mirror, there was also an "old" null corrector technology, decades old, using lenses. Perkin Elmer was worried this was not good enough, and therefore built a theoretically better mirror based corrector. And it's true the "old" technology said the mirror was off, despite the new technology saying it was OK, but they chose the believe the new. But it's not like there is some simple test an old telescope maker could have run to see the error - the last telescope that had a mirror type where this was possible was the Palomar mirror. The disagreement between the older and newer measurement techniques is covered in the article and may be the source of the story. LouScheffer (talk) 14:44, 14 November 2014 (UTC)

Ignored error?

P. 512 of the Dunar article does not quite say or imply the company just ignored the error. It does say something like they believed the results "were less accurate than the primary device which reported that the mirror was perfectly figured". It also says on p. 513 that PE didn't use the required expertise and they failed to verify their results. Myrvin (talk) 20:39, 26 November 2014 (UTC)

I've had a go at clarifying this. Myrvin (talk) 20:58, 26 November 2014 (UTC)

Agree that "dismissed" is more accurate than "ignored". But while quotes are often helpful, but this one seems to take 3 lines to say they did not believe the 2 null correctors, since they thought the reflective one was better. So I think it's better to say just that. LouScheffer (talk) 03:58, 27 November 2014 (UTC)

Vandalism

When I searched for hst 5 the page came up but the description of this page was:

"Hubble Space Telescope (redirect from Hubble Space Telescope (HST)) can't find ma berries buttt i found this *lick The Hubble Space Telescope (HST) is a space telescope that was launched into low Earth orbit in 1990, and 116 KB (13,167 words) - 05:17, January 8, 2015"

This is vandalism that was reversed by a bot, but somebody should either go into the search metadata and correct the listing, or mark this page for recrawl. (I do not know how to do this or where to report it, or how ofetn the whole system undergoes recrawl but somebody reading this does). TeigeRyan (talk) 20:31, 8 January 2015 (UTC)