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Comment by elil17 | Hacker News Reader

When I visited Arecibo (which I highly recommend but the way - one of the coolest things I’ve ever seen), the intern giving me a tour told me that Arecibo was essentially the main way we had to detect asteroids that might hit earth. Without it, we may not have enough time to launch an asteroid redirect mission.

If that’s accurate, it seems penny wise and pound foolish to have spent ~$300 million on the DART test but then not spend the extra ~$50 million needed to actually detect an asteroid coming towards us.

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The Arecibo dish was not steerable, so there are large parts of the sky that it couldn't see.

China built a similar radio telescope that went into service in 2016. https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Sp...

Are you sure? I recall that the dish was spherical, not parabolic, and had a movable receiver mounted on cables; moving the receiver adjusts the direction from which signals can be received. Indeed, Wikipedia claims that it was steerable [0].

[0] https://en.wikipedia.org/wiki/Arecibo_Observatory

You're kinda both right; the dish itself was fixed, but the system as a whole still had limited steerability because it was (spherical?) instead of parabolic, allowing 20° of the zenith.

This was still a lot more limited than the horizon-to-horizon of the other iconic radio telescope type: https://commons.wikimedia.org/wiki/File:CSIRO_ScienceImage_8...

The competition for giant Arecibo-like telescopes is arrays, and since their cross section goes to zero as you turn them towards the horizon (straight up and they're spaced out, from the horizon they're in a line), they are limited within some reasonable range of the zenith as well.

Most of the large (more than a few hundred meters) potentially hazardous asteroids are thought to have been found. However, there are some locations (relative to Earth's orbit) that are difficult to view from the ground, because you can only observe them at twilight. The best way to find those last remaining potentially hazardous asteroids would be to launch a space telescope to the Earth-Sun Lagrange Point 1.

In the grand scheme of things, this type of mission wouldn't cost that much, but so far, nobody has made the decision that making sure Earth doesn't get hit by an asteroid is worth an investment of a few hundred million dollars.

> nobody has made the decision that making sure Earth doesn't get hit by an asteroid is worth an investment of a few hundred million dollars.

This is not true. NASA spent over $300 million to test DART, an anti-astroid planetary defense system.

And yet, a straightforward mission that would identify all remaining potentially hazardous asteroids hasn't gone forward. DART is great, but it's useless if you don't see the asteroid coming long in advance.

It seems that Starship well greatly upend these calculations and considerations. When launching 100 tons of payload costs $10 million, we should start seeing a lot more science being launched.

We really just need one telescope at L1. That's all.

With ‘large potentially hazardous asteroids’, thinking we have found most of them doesn’t really seem that reassuring.

Like the mayor giving a press conference in front of the zoo saying “Most of the large, maneating lions are thought to have been located”.

Late last year, NASA approved development of NEO Surveyor, an infrared telescope that will search for near-Earth objects from Sun-Earth L1. NASA estimates that it will launch in 2028 and cost $1.2 billion.

https://spacenews.com/nasa-confirms-neo-surveyor-for-2028-la...

When I visited Arecibo [...], the intern giving me a tour told me that Arecibo was essentially the main way we had to detect asteroids that might hit earth.

Arecibo wasn't used for detecting asteroids—it was used to characterize asteroids that were detected by other means. Arecibo observed asteroids via radar. The power necessary for a radar observation goes up very quickly with distance to the target (proportional to distance to the fourth power), so radar would generally be a poor choice for hunting for asteroids.

The problem is most people with $300 million aren't willing to spend it on this. They're more worried about how to get another $300 million. That mentality how they turned $150 million into $300 million in the first place.

Government spending on the other hand, is mostly decided by poor people (majority of voters) who are more worried about tomorrow than 1000 years from now.

> Government spending on the other hand, is mostly decided by poor people (majority of voters)

Government spending is decided by Congress and the President, who are not poor people. There is a convoluted selection process in which rich people (donors) select the pool of candidates from a group of rich people, and then they let poor people vote on which of the rich people selected by other rich people they would like to have make decisions for us.

On a practical matter it is clear poor people do not make decisions because poor people want things like universal health coverage, but we do not have that.

> Government spending on the other hand, is mostly decided by poor people (majority of voters)

Government spending is mostly decided by huge corporations, firstly the arms industry. If poor people controlled our budget we wouldn't have throngs of homeless people in every city in the country.

> Government spending on the other hand, is mostly decided by poor people (majority of voters) who are more worried about tomorrow than 1000 years from now.

I’m fairly sure studies of voter sentiment & positions vs. legislative activities and executive priorities do not back up this guess.

Yeah, I am sure poor people prefer to give dozens of billions every year to Lockheed Martin, Boeing, Northrop, General Dynamics, BAE et caterva instead of affordable public housing and public health.

I see the homeless living on their tents, the inner city blacks and the white unemployable rednecks gnashing their teeth in unison: "Don't you dare buy a single F-35 less to give us some fucking stinking doctors!"

That's exactly how it is, a perfect democracy.

uhh, I am scratching my head at this. You do realize an "asteroid redirect mission" is science fiction right? Not something we actually have the capability to do.

You mean aside from the DART (Double Asteroid Redirection Test) mission already launched, tested, and deemed a success?

    As a part of NASA’s overall planetary defense strategy, DART’s impact with the asteroid Dimorphos demonstrates a viable mitigation technique for protecting the planet from an Earth-bound asteroid or comet, if one were discovered.

https://www.nasa.gov/news-release/nasas-dart-mission-hits-as...

Sure, it's not like we have a fleet of Asteroid Redirection modules lined up ready to go .. but it is an actual capability we have and something we have already done.

This altered the orbit of one asteroid around another. It's moot. You have to either eliminate the asteroid (good luck) or alter it's orbit around the sun (those delta-V numbers just got huge) to be meaningful.

Suggesting we have an "actual capability" is just conjecture. It's a NASA project. According to them, the Space Shuttle was a successful program.

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