[mmoche]

I am confused as to why "repair the thing before it catastrophically fails" is not the best of the available options. Decommissioning a facility like this is a loss for science globally, even if there are alternatives available. Telescope time is precious.

[toomuchtodo]

You would have to dig into who is providing funding and how the funds are being spent by UCF, Universidad Ana G. Méndez, and Yang Enterprises Inc (the loose consortium tasked with O&M of the facility).

See the latest update on https://www.ucf.edu/news/update-on-arecibo-observatory-facil.... Just a month ago, cable sag surveys and safety assessments were done, and a structural monitoring instrumentation system was installed. I'd be curious what those reports show, and if this most recent failure was anticipated. If it wasn't expected, what was the value of the work last month?

[gambiting]

I'm not saying that he should, everyone can spend their money as they wish, but just as a fun thought exercise, could a private, extremely wealthy entity do it? Say, could Jeff Bezos or Elon Musk just say "yep, I'll pay for all the repairs from my own pocket"?

[toomuchtodo]

Absolutely, but then they should assume control of operations to ensure a tight ship is run. If efficient use of funds is demonstrated, further funding (whether private, public, or crowdsourced) should follow. You don't want to encourage mismanagement of limited funds.

Edit: Upon further thought, I think it's an exceptional idea that SpaceX submit itself as an O&M vendor for NSF (and perhaps even NASA) RF/observatory facilities. Between launches and StarLink, they have demonstrated lean execution.

@ISL: Your point is noted, but SpaceX has a $50-100 billion valuation, access to capital markets, and StarLink is likely to be very profitable. I don't think it's fair to paint them to be in financial peril as they were during their earlier years. UCF's entire budget is $2 billion, and they can't scrap together a few millions dollars to properly care for Arecibo. UCF and SpaceX have each demonstrated their level of capability.

[ISL]

SpaceX has been so lean that they have been one launch away from bankruptcy. That isn't the right model for a scientific user-facility with a half-century expected lifetime.

[njarboe]

Are you talking about back in 2008 when the third launch of the Falcon 1 failed to reach orbit? That was a long time ago. They are not near that situation now. The main goal of SpaceX is creating a human civilization on Mars. Seems to me like they do have the right combination of getting things done and the long view.

[thro1]

Couldn't it be receivers on Starlink satellites plus some computing power instead?

[teraflop]

In theory you could do interferometry with a lot of orbiting radio telescopes. I'm no radio astronomy expert, but I can see a lot of practical problems with this idea.

For one thing, if you want the same signal-collecting power as the Arecibo observatory, you need dishes with the same total area. Since Arecibo is 1000 feet in diameter, if you put dishes on every one of the 12,000 satellites in the initial Starlink constellation, they would each have to be over 9 feet. That's about the same size as the chassis of the satellite itself.

In order to do anything useful with the collected data, the receivers need to have very precisely synchronized clocks, and their relative positions need to be known to within a small fraction of the wavelengths you're interested (which for Arecibo can be on the order of centimeters). I'm not sure whether GPS receivers alone would be enough to meet these requirements -- you might need to add atomic clocks to every satellite as well.

Now you have to think about how to aim the antennas. Presumably you can't just reorient the entire satellite, because its main job is to keep its ground-facing antennas aimed at the ground and its solar panels aimed at the sun. So you need to add a separate antenna pointing mechanism, with a fairly wide range of very accurate movement along multiple axes, so that all of the radio antennas can observe the same region of the sky simultaneously.

Presumably the Arecibo telescope itself is connected to fairly sensitive, low-noise, specialized signal processing equipment. You would have to take all of this equipment, design a space-rated version that can fit on a satellite, and then manufacture 12,000 of them. You also need to add enough solar panels to power it.

All of this would add a huge amount of mass to every satellite, which would make them way more expensive to launch. Note that this applies to to both the monetary cost and the opportunity cost of SpaceX's annual launch capacity.

Finally, the Starlink satellites have a roughly 5-year design lifetime, so it's not enough to build this colossally expensive telescope array once; you have to keep building and launching half a dozen replacements per day for as long as you want to continue using it. There's no way it would ever be cost-competitive with a ground-based observatory.

[thro1]

It's serious question, from the future.. (but no answer and downvoting - what's wrong ? I know Arecibo is very important)

..about radio telescope arrays, computer power and feasibility. Astronomers complain that they lost the sight of the stars because of Starlink. Could it be somehow compensated by an array of moving, smaller radio telescopes in orbit?

Britannica: 'The world’s most powerful radio telescope, in its combination of sensitivity, resolution, and versatility, is the Very Large Array (VLA) located on the plains of San Agustin near Socorro, in central New Mexico, U.S. The VLA consists of 27 parabolic antennas, each measuring 25 metres (82 feet) in diameter. The total collecting area is equivalent to a single 130-metre (430-foot) antenna.'

https://www.scientific-computing.com/analysis-opinion/harves...

[rasz]

>Telescope time is precious.

Clearly not precious enough to fix the observatory.