$50SAT – Eagle2 (2015) | Hacker News Reader

$50SAT – Eagle2 (2015)

50dollarsat.info

56 pointsthcipriani23 comments

$250 sat. Free (or unquantified) launch cost, labour priced at $0.

Awesome stuff. Looks like they used a metal measuring tape as antenna. I totally love the concept.

Lots of serious satellites use tape measures. They're made of high quality spring steel and reliable mechanisms for deployments.

I was a little suspicious of this claim but nope, it's absolutely true: https://airandspace.si.edu/collection-objects/satellite-ers-...

Wrap fishing line (monofilament) over the coiled up antenna and across a electrical resistor that gets connected to a battery/capacitor as it is deployed. Resistor heats up monofilament line melts antenna does not go "sprooooing!" because there is no sound in space.

https://www.pdxaerospace.org/

OTRAG (failed German rocket launching startup) did that thing with the measuring tape antennas in the 1980s. They also used Volkswagen windshield wiper motors as rocket nozzle actuators, iirc.

I read about them in the 70s. Bundles of smaller rockets, lots of venturi and sea launches. Hard to compete with state actor rocketry at the time. And multi-nozzle rocketry was still a minefield then (I believe it was said to be why the Russian giant launcher failed, where Saturn V succeeded by being brute force simpler to engineer)

In some ways, OTRAG feels like spaceX three decades too soon.

> I believe it was said to be why the Russian giant launcher failed, where Saturn V succeeded by being brute force simpler to engineer

Many nozzles can actually be beneficial (engine-out capability) or neutral (Soyuz rocket family flies for 60+ years with 32 nozzles running at the start).

According to Chertok, problems were with engines quality themselves (e.g. insufficient manufacturer experience), CORD system (new electronic system to manage many engines), absence of test stands for integrated first stage (given single-start engines, could be insufficient). Number itself isn't a problem, as demonstrated by e.g. Falcon Heavy - it's the novel N-1 rocket, which both failed and had many engines, which leads to conclusion these are related a certain way.

OTRAG was involved in some juicy scandals whose specifics I don't remember. I'll have to watch the movie that rkagerer mentioned sometime. There is a wikipedia article, but it seems to gloss stuff over.

For anyone curious about the OTRAG story I highly recommend the movie Fly Rocket Fly

Plus a fraction of a $29 Million launch... https://en.wikipedia.org/wiki/Dnepr_(rocket)

Oh Hey ! I actually know a bit about this..

If you want to watch a talk by this guy about the satellite. Go here.

https://www.emfcamp.org/schedule/2016/101-the-story-behind-5...

The $50 satellite Eagle2 Launched into Space - https://news.ycombinator.com/item?id=7671209 - April 2014 (2 comments)

Any ideas How much does it cost to launch one of these $ ?

Based on past experience it's either free for you or at least many tens of thousands. I was involved in a cubesat group and that's a big issue we had, we couldn't make an innovative payload that would get us sent for free and none of us had that kind of money sitting around.

So it operated for a year and a half, and now it's a $50 piece of space junk?

I will take this question at face value. No, it re-entered, and is not orbital junk. https://www.n2yo.com/satellite/?s=39436#results

Ah, that's good to know. I was concerned at first because their "current location" link [1] shows an object still in orbit. But I realize now that the site defaults to showing the ISS if it can't find the object.

[1] http://www.satview.org/?sat_id=39436U

Low orbits (eg Starlink) decay very quickly - if the satellites thruster failed, it would burn up due to drag within 8 years (typically satellites deliberately de-orbit via thruster at EOL).

Cheap satellites almost exclusively use low orbits since they are cheaper to reach.

A year and a half is really good for a $50 sat. Some makeshift ones only last hours, like suitsat-1.

https://en.m.wikipedia.org/wiki/SuitSat

A year and a half is amazing for off-the-shelf non-space-rated parts. Vacuum, radiation, temperature differences of hundreds of degrees all wreak havoc on electronics. A year and a half is really excellent.

And like others mentioned these types of experiments are put in such low orbits that they decay quickly after their service life.

I assumed this was going to be SAT solving as a service.

I thought it was Dogecoin to a dollar but with Bitcoin instead, and more like Dogecoin to a hundred thousand dollars. https://cryptocurrencyfacts.com/what-are-sats/

At $50 a sat, 1 bitcoin would be worth 5 billion dollars.

I thought this too. Gave my eyes a yoga session before clicking, then I realised it was something interesting!

Agreed

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