Hacker News Reader

Comment by lutorm | Hacker News Reader

This seems mostly to be a PR gimmick. While it seems like a cool thing to do "just because we can", there is no compelling advantage to putting a 200mm telescope in space. You don't get much sharper images by being in space with such a small aperture. And launching a space telescope for people to take pictures of themselves... I don't even know where to start.

View on HN

The purpose of the Arkyd is to discover NEOs. Right now there are no low-cost, mass-produced telescopes in LEO, and asteroid discovery is driven by government-funded projects centered around universities. The compelling advantage of this telescope is that it circumvents the cost and bureaucracy necessary to discover asteroids.

Of course, the kickstarter/public relations aspect is not essential to all this, but Planetary Resources gets a ton of public interest and they want to capitalize on/engage with people who are interested in their mission to mine asteroids.

Did you hear about b612 foundation? they also want to discover NEOs with a space telescope, and they don't want to do it for business purposes. last time I've checked they said it's going to cost about $450m to do it. There is no chance that PR will be able to do it much cheaper. They may be able to launch their toy and snap some pictures but I don't think they will be able to do much more with it.

B612 wants to make a big telescope and put it in an orbit very far from Earth. PR's approach is different - make many small, cheap Arkyd telescopes and take advantage of economies of scale. They don't want to concentrate resources and risk in a single large object.

Building a small satellite is quite affordable, but commercial launch costs are a problem. There are several funded kickstarter projects whose goal is to deploy one or more satellites in orbit for much cheaper than what PR is trying to raise.

People also overestimate the difficulty of finding asteroids. Asteroids are still being discovered by amateur astronomers on Earth. It's estimated that there are millions of undiscovered objects. A big space telescope is an advantage but not a requirement.

other kickstarter projects:

  http://www.kickstarter.com/projects/880837561/skycube-the-first-satellite-launched-by-you

  http://www.kickstarter.com/projects/575960623/ardusat-your-arduino-experiment-in-space

  http://www.kickstarter.com/projects/zacinaction/kicksat-your-personal-spacecraft-in-space

I asked an astronomer friend of mine to look at the specs and got a small list of advantages:

-No atmosphere. Seeing would still be a considerable factor; getting 1 arcsecond resolution on Earth is not easy.

-No clouds

-Ability to focus on the same object for an extended exposure

-Infrared

-Can look north and south

There are a lot of advantages to this, even with their aperture size.

Actually, not infrared but UV. They seem to have filters in the vacuum-UV which can't be observed from the ground. The near-IR out to 1.1um that they are going out to is not really a problem from the ground.

Honest question: Is it possible that they're not worried about sharper images of distant objects insomuch as being able to survey much larger portions of the sky with a large array of satellites?

The compelling advantage is that they're making it available to the public to use.

If you add up the total time the telescope will be available to the public in minutes (please, correct me if I'm wrong) you get:

30 * 1000 + 3 * 30 * 500 + 3 * 30 * 500 + 10 * 30 * 100 + 25 * 30 * 50 + 25 * 30 * 50 = 225000 minutes = 156.25 days

This is not really a lot. The remaining time will be used by Planetary Resources. There is no way for public to continue using the telescope after that.

Assuming this is where they stop, and they don't build a system for purchasing time later on...

But what I'm saying is the public can just get a 200mm telescope on the ground themselves. No need to launch it into space.

I live in Portland, Oregon. Every time we wanted to use a telescope to see some planetary wonder it has been cloudy. Hard to keep my kids excited about space without seeing much of it :)

You can rent time on a telescope in another hemisphere and timezone right now, over the Internet.

Atmospheric interference makes it impossible to observe in some wavelengths on the ground.

The public is already allowed to use the Hubble. You just have to send a proposal that is compelling enough for them to grant you time on the scope.

Do you really think that they will be able to upload a picture, display it on a LCD, snap picture of their setup and send it back to Earth and do it hundred of times with a prototype full of untested tech?

Yes.

a) The vast majority of satellites are "prototypes." They're built a few at a time, extensively tested, then launched. In the case of satellite frameworks like Cubesat, they're open source and tested every time someone launches one.

b) This is not untested tech, at all. Cubesats have been using consumer technology in satellites extensively, both by startups, hobbyists, and academia (doing advanced stuff like orbital reconfiguration, atmospheric sampling, telecommunications, etc). Combined with NASA's existing suppliers for aerospace grade components, these satellites which have a really high success rate.

Cubesats don't use LCDs. mainly because LCD won't work under low temp conditions, so that's problem number one. Problem number two - we don't know how Arkyd will be propelled. They are selling possibility to point the telescope anywhere but what about changing it's direction? How many maneuvers they can do with limited amount of propellant on board? There is more questions, but really what's the point?

LCD temperature specs are for ATP, where heat transfer functions very differently from vacuum. With radiation being the only way energy enters or leaves the satellite's thermal system, all the satellite has to do is heat the LCD faster than it is radiating heat. This is the case for most instrumentation on satellites and thermal is one of the most important and well understood systems.

Colloid thrusters (or other ionic propulsion), or even a chemical hybergolic propellant (hydrazine + oxygen for example) would work perfectly for propulsion. This is a solved problem, so much so that there are off the shelf modules for cubesat propulsion.

Reply on news.ycombinator.com