Eric's weekly post #2

Woo hoo! A whole week and I haven't yet broken my promise to post once a week. (It's not Sunday here yet, so it still counts.)

I've been on pseudo-vacation since I submitted the NASA proposal on tuesday. My parents are in town, and Angela is doing her best to make sure I don't work on my "vacation." She's taking a nap right now, so as long as she doesn't wake up, I'm in the clear.

I don't have anything earth shattering to discuss today. I should mention that some Astropulse (a search for radio pulses that could come from ET or from evaprating black holes or pulsars) work units went out in beta last week, for the first time in a long time. You can get some description of Astropulse here. Yes. You read the date on that right. Astropulse has been stalled due to lack of forced labor... um... I mean a graduate student. Josh von Korff has been on the case for a little while and is making some progress.

Since I don't have that much new to discuss, I'll answer a question that appear in response to last week's post. The question was "Will the Allen telescope array render SETI@home obsolete?" As with most things in science, the answer is yes and no.

Any telescope will have its advantages and disadvantages. Those advantages and disadvantages affect how science is done with that telescope. There are really two characteristic to a telescope that affect how capable it is at doing SETI. Those are the collecting area, and the size of the field of view of the telescope (also called its beam size). For a single dish, those two parameters are inversly proportional to one another. A small dish has a large field of view. A small dish has a large field of view. That explains why you don't need a telescope in order to align a 14-inch (35 cm) digital satelite TV dish.

Arecibo's advantage is obvious. It's big. Really big. That means it has a large area for collecting radio signals. It also has the smallest beam of any single radio dish the new multibeam receiver has 7 beams, each of which is 3 arcminutes in diameter. (The size of a baseball seen from 100 meters away.)

The ATA is an array of radio telescopes. Arrays allow you to break the proportionality between area of the dish and the beam size. In an array, the size of the beam is inversely proportional to the largest spacing between the telescopes of the array, and the collecting area is proportional to the number of telescopes.

If the ATA gets fully assembled, its collecting area will still be less that that of the Arecibo telescope, but its beam size will be much smaller.

With Arecibo, we tend to do surveys. We look at the whole sky for potential signals. ATA, because it has a smaller beam is more suitable for point searches. If you want to look for signals from the 500 nearest stars, you want ATA. If you want to look for signals coming from anywhere in the sky, you want Arecibo or another large single dish (Parkes, GBT). To do both, you want both.

Of course, right now we have funding problems, which you have no doubt heard about. And Arecibo has funding problems, and will be shut down in five years if alternative funding isn't found. You may not have heard that ATA also has some funding issues. Right now I am not certain what fraction of the telescopes in the planned array will be built. The electronics that are required to generate the beam from the telescope data (the beam former) is also expensive, so funding determines how many simultaneous beams can be used. I think the current plan is for at least three beams, but if the beam former is behind schedule funding constraints may reduce that to two.

For what it's worth, my opinion is: "When you are looking for a needle in a haystack more eyes are better than fewer."

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Eric
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For what it's worth, my opinion is: "When you are looking for a needle in a haystack more eyes are better than fewer."

Of course, right now we have funding problems, which you have no doubt heard about. And Arecibo has funding problems, and will be shut down in five years if alternative funding isn't found. You may not have heard that ATA also has some funding issues.

Wow. Things sound really grim. What's the source of the funding cuts? Is it our government and it's "war on terror", or was there a pre-determined amount of time they were willing to fund it before they felt it was time to cut it off? Or what?

What does that mean personally and professionally for you? Worse case scenario, if things were shut down sooner rather than later, what would you do next? How would you feel about it?

(cross-posted in Technical News section)


@Eric,

Any chance of finding out what discussions you all had about the BOINC User Survey Results.

Any surprises crop up?

Are you going to be, or have you started to, implement anything as a result of the survey?

Have the results confirmed anything in particular that you may have suspected?

How useful did you find the survey?

Will the survey be published in a paper, explaining the results and providing some conclusions/comments?

And many more questions on a similar vein.....

-kinhull


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Join TeamACC

Sometimes I think we are alone in the universe, and sometimes I think we are not. In either case the idea is quite staggering.

BOINC User Survey Results.

Will the survey be published in a paper, explaining the results and providing some conclusions/comments?

I know that, per David Woolley's messages of several years back, the stick Seti receiver hadn't been using the entire Arecibo dish at one time, ever. . . . It is not clear how much of the big dish is used at any one time by Alfa.

Eric, I heard some years ago about plans to make a super-telescope using three telescopes placed different places on the Earth, so the whole planet will function as a telescope. Has this been developed further? Or was it only discussions?


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Eric, I heard some years ago about plans to make a super-telescope using three telescopes placed different places on the Earth, so the whole planet will function as a telescope. Has this been developed further? Or was it only discussions?

Eric, I heard some years ago about plans to make a super-telescope using three telescopes placed different places on the Earth, so the whole planet will function as a telescope. Has this been developed further? Or was it only discussions?