Friday, May 22, 2009

A (Long) Last Hurrah for the Hubble

Hubble viewed from AtlantisAmid the clutter of the week I missed commenting promptly on the completion of the final Hubble servicing spacewalk last Monday.

It has been (yikes!) 19 years since the Hubble Space Telescope was lofted into orbit aboard the Shuttle Discovery in April of 1990. Time and triumphs have produced a generation happily unaware that the Hubble, as launched, was one of NASA's more embarrassing blunders. Somehow, in building it, no one thought to check the main mirror, which turned out to be incorrectly figured so that it produced only blurry images. Face, meet egg. But in 1993 astronauts fitted it with what amounts to a prescription monocle, and everything snapped into focus.

I won't try to list what Hubble has taught us since the eye doctor made a house call, except that the servicing missions themselves have confirmed our ability to do exacting physical work in space. (A robotic servicing mission was ruled out for the latest upgrade: Robotics are not up to the task.) Well done, Atlantis crew and predecessors!

The Hubble is now expected to have another 5-10 years of service life. Meanwhile, treat yourself to some eye candy here.


Update 1: Atlantis returned safely today (Sunday), capping this tricky and outstandingly successful mission. The landing was delayed and shifted to California by persisting rain at Cape Canaveral. (Too bad Florida can't send some of that rain our way - they have it, we need it, but it's our dry season now.)


Update 2: President Obama has named Charles Bolden to be the new head of NASA, pending Senate confirmation. Bolden is the second former astronaut to head NASA, and - how's this for synchronicity? - was pilot (second in command) of the mission that put the Hubble in orbit. Seems like good news for the manned spaceflight program.


Update 3: Be sure to read the comments for Cool Information from a member of the Hubble science team!

17 comments:

polemarkh said...

I would note that COSTAR (the corrective optics you describe) was in fact removed in this servicing mission, and that none of Hubble's instruments have required it since SM3B in 2002.

And, as one of the crowd working at the space telescope science institute, I'll note in passing that with the completion of the EVA, the real work has begun. With the NICMOS shutdown last year, Hubble currently has *no* active science instruments -- everything on board is either not working, newly repaired, or newly installed. So the next step is to bring the instruments from simply being alive (which was tested at installation/repair during the servicing mission), to being ready to do science. Expect a press release in September with some incredible early release observations.

Rick said...

I had no idea that the original corrective optics had been phased out! Do all the recent/new instruments have their own correctives, or do they share a replacement? (Or a combination of both?)

What happens now? A calibration process to get everything adjusted and in sync? I'll be keeping an extra close eye on Sky & Telescope's news notes come September!

Rick said...

And I should have added - congrats are in order to all of you!

polemarkh said...

Sorry, I likely should have responded earlier (and incidentally, since signing in with my Googla account doesn't seem to preserve it, I'm Brian York, whom you may recall from sfconsim-l amongst other places).

Essentially you're right that all of the current instruments have correction built into their optics. The most notable exception is the Cosmic Origins Spectrograph (COS), which happens to be the one I'm most closely involved with. For COS, the far UV channel (FUV) is only corrected in the dispersion direction (which was thought to be a worthwhile tradeoff for one fewer mirror, and thus a better sensitivity, especially because the FUV channel is designed for spectroscopy first last and only).

As for what's next on the table, it is indeed a long calibration and testing process for the instruments (well, long for the new instruments, much shorter for the repaired instruments). Indeed, the new instruments haven't even seen first light yet (all of the functional tests were done with internal sources, and the UV instruments didn't (and don't) even have their detector power on yet, in order to make sure the pressure is as low as possible, and thus avoid arcing). On the one hand, by the time SMOV (Servicing Mission Observatory Verification) formally ends in late August, we'll already have several weeks of mostly taking science observations. On the other hand, if your science observations are being taken early, and you want to see them as soon as they're available, you need to sign an NDA stating that you won't release your data until the early release observation press release, which is scheduled for early September.

At this point, I'm not sure how much of what happens during SMOV is/will be kept secret, although the astronomical community is both small enough and tightly enough connected that trying to maintain a total blackout would be doomed to failure. Still, for most of us, the real work of the servicing mission is starting this week.

Rick said...

Brian - Yes, I recognize you from SFConsim-l! ('Polemarkh' also implied an interest in Stuff That Blows Up Good, not a total surprise for visitors to this blog.)

Presumably most researchers who get an early start will still be gathering/analyzing data come September. But I suppose that if someone's raw imagery showed, say, an alien ship coming our way, it would probably tend to leak out. :-)

polemarkh said...
This comment has been removed by the author.
polemarkh said...

Sorry, the last comment got overwritten by a previous one due to my being careless, so let's try it again.

On the one hand, I agree that the detection of an alien ship would be released quickly, on the other hand I don't think it's likely to involve anyone breaking their agreement, because I think that STScI would be as involved in the discovery (and the press release) as the astronomer whose data it was. I can offer here a (brief) summary of what would happen if an alien ship was detected in science observations over the next few months. Now, I don't have absolute and certain knowledge of how things would go, but I do have at least some ideas, based on how big observatories work.

First, if you're observing in the UV, the alien ship (especially if it's using a torch) might exceed either the local or global bright object thresholds, and cause the detector to safe. In that case, you almost certainly have a very quick response, and an almost immediate investigation, because whatever field you're looking at has been cleared for bright objects, or your observations wouldn't have been approved. And extremely bright UV sources don't just appear out of nowhere, so you're almost certainly going to get very quick follow-up, including (possibly) ground-based observations, since this is a potential GRB (or equivalent). (Actually, and parenthetically, this is why I think that any alien ship using a torch drive in or near the solar system would probably be detected first by SWIFT, assuming that it has the energy densities we usually talk about when discussing torches).

Second, if you're taking a spectrum, then you have another spectrum either overlapping what you were trying to observe or next to it (or, possibly, especially for COS, your acquisition locked onto the alien instead of what you were trying to observe). In that case, if you can make a convincing case for the object being an alien ship (or at least something very strange) based on its spectral properties (and if it's either a torch or a strongly blueshifted solar spectrum, you probably can), then follow-up observations (either with HST or with ground-based observatories) are likely (again) to start fairly quickly.

Thirdly, if you're taking an image, but the alien ship is resolved, then (again) there's probably going to be a fairly quick turnaround, especially if it's obviously artificial. If you have a moving object that's resolved, it probably also gets attention, even if you can't see what it looks like due to blurring. If you have a moving unresolved source, it will likely eventually get attention, especially if you were taking multiple colours of observation, and the object has the wrong colour to be an asteroid, comet, or KBO.

Finally, if what you have is either a stationary point source or a not-obviously-artificial resolved source, it could take quite awhile for anyone to follow up, simply because it's not obvious what you're seeing. Indeed, it might never be followed up, especially if it's only present in one of a series of exposures (in which case it might well be classified as a cosmic ray and edited out of the reduced data).

Either way, the procedure probably looks like this. You get your data, you look at it, you see something strange (and something strange that might mean that your data is bad, or that might be preventing you from seeing what you were trying to see). You e-mail the institute helpdesk, asking what went on (because possibly it's a flaw with the new instrument). The helpdesk looks at it, can't figure out what's going on, and the question starts being circulated internally in the instrument team. If it's possible to figure out it's an alien ship with high confidence, someone eventually does, and you get contacted by the institute, probably about arranging a joint press release. Especially with a new instrument, I don't think that any researcher is going to assume they've seen aliens without at least checking with the helpdesk in case it's a known (or detectable) problem with the instrument.

Rick said...

Wow! I was using 'alien ship coming' just as a flippant stand-in for 'dramatic finding that would tempt researchers to break embargo.' But since the subject came up it certainly merits a full discussion. :-)

What is SWIFT? I presume an instrument that scans the whole sky on a pretty frequent basis. In practice I imagine an alien ship would more likely be detected that way than by a telescope like the Hubble, designed to get deep hi-res imagery of a fairly small patch of sky.

That said ... it stands to reason that an intruder would first be detected as an anomaly, and the first reaction of the observers would be to think that something had gone south with the instrumentation. So the instrument team would be involved pretty much from the get-go.

(I especially like the scenario of the instrument 'safing' from overload, or locking onto the torch flare instead of the object it was supposed to point at.)

From a dramatic perspective it would make a great sequence. First the research and instrument teams puzzling and grumbling over an apparent malfunction, someone - probably flippantly, as I did - making the off the wall suggestion that the anomaly is an alien ship, then the dawning realization that that is the least implausible explanation, and presumably calling other instruments into play to see what the hell is going on.

polemarkh said...

SWIFT (findable here: http://www.nasa.gov/mission_pages/swift/spacecraft/index.html) is another space telescope, designed to detect gamma ray bursts. As such, it's beautifully designed with a large field of view able to detect X-ray and gamma ray sources as quickly as possible (and then follow them up, or pass them along to ground-based telescopes for follow-up). As such, whilst I'm not sure if it scans the entire sky often, it does have a large field of view, and it's designed to detect transient events quickly.

And yes, something like SWIFT is the most likely (or Kepler, since it's also designed to stare at a particular large field of view, although SWIFT concentrates on the shorter wavelengths) to detect something. I'd say that it would be one of the ground-based telescopes, but really (especially if we're talking about torch drives), one of the unambiguous signatures would be short-wavelength radiation, which is only really detectable from orbit.

But yes, if you're looking for verisimilitude, it's worth thinking about how things would register. The reason I thought about locking onto the wrong target is that I work on COS in particular, and because COS has such a small field of view, acquisitions are currently designed around a search pattern which (by default) locks on to the brightest target it can see (there's also the option to lock on at a predefined offset from the brightest target, in case you know there's a bright target near what you want to look at). As such, something coming out of nowhere might well cause an error like that -- it's low-probability, but (sadly) so too are alien spacecraft.

The thing is that, aside from SETI, astronomy isn't set up to look for alien spacecraft, and even the radio telescopes are designed to look for distant signals. So, whilst we have an excellent set of telescopes, most of them just wouldn't be looking at the right thing, and would see an alien ship only by accident. In fact, if the ship wasn't resolved, and didn't move during the exposure, it might just be seen as another faint star (or something), and never further investigated. And if it only turned up once, it might be considered a glitch (which, honestly, is reasonable, because you get glitches fairly often, and (so far as we know) you don't get alien ships nearly so often).

Unless an alien ship is visible in the optical, it's going to be missed by the group most likely to see any such ship -- the amateur astronomers. And if that's the case, it will be detected only by accident. It's unfortunate, but it's really what you're stuck with. That said, accidents do happen, and if the torch lighting up (or the FTL drive on the edge of the system) looks like a gamma ray burst, that's probably the best way to (plausibly) have it followed up quickly, and detected.

Rick said...

Faint emissions that were taken for just another background star could be useful later. Once an alien ship was recognized, people would pull up previous imagery from that part of the sky to look for unnoticed detections. (ISTR this has happened with sundry astronomical discoveries.) Alas, I imagine that anomalies that are taken as mere glitches simply get deleted.

If our assumptions about torch drives are valid (a middling-size if, at least!), optical band detection is plausible. The torch flare itself is probably far UV or shorter, but the lantern structure should be shedding waste heat at a few thousand K, so a lot of it in the optical band.

One of my early posts mentioned detection by amateur astronomers, admittedly in a rocketpunk setting (an interplanetary task force, which by modern standards we'd expect to be detected as soon as it lit up its departure burns). Do a local search for 'a little faux Heinlein.'

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