Self-Healing Transistors for Chip-Scale Starships | Hacker News Reader

Self-Healing Transistors for Chip-Scale Starships

spectrum.ieee.org

73 pointsrbanffy35 comments

Previous discussion: https://news.ycombinator.com/item?id=13161879

> "the craft could accelerate to one-fifth the speed of light"

At that speed, wouldn't this little device be ripped to shreds by dust, radiation, and loose atoms or ions?

Well, as long as you don't care about stopping any time soon, it still can accelerate a ship to one-fifth the speed of light...

Not sure if space has that much stuff in it outside the heliosphere...

Some numbers here: https://en.m.wikipedia.org/wiki/Interstellar_medium

It will still be travelling at that speed when entering the corresponding area of the target system. If it could survive, it would be interesting to know what kind of observations could be made by a single-chip sensor travelling at that speed. No planetary close-ups surely.

Good point. And yeah I wonder how accurate its trajectory would be after travelling multiple light years. Cool engineering problems!

This is a fascinating read: https://arxiv.org/pdf/physics/0610030.pdf

Yes. It also needs a kinetic shield.

Even assuming you can slow down the chip once it gets to the solar system, do we even have a way to send a signal back?

Perhaps, the sail could modulate the reflected beam? That way, all of the heavy communications gear can stay in our own solar system.

Instead of trying to stop at the destination, you could instead send a stream of these tiny expendable probes past the target. Each one would get, say, a microsecond to take a snapshot, and then it would spend the short remainder of its life relaying the raw data.

To do a chemical analysis, some probes could be sent on relativistic collision course with the subject planet, and other probes could watch the impact. It would be a scale-up of NASA's Deep Impact mission from 2005.

A relativistic impact sufficient to allow chemical analysis from space is probably sufficient to kill creatures that may live on the planet. I'm not entirely comfortable with this.

I don't think a 0.1g probe would make it through an atmosphere at any speed. The targets I had in mind, were moons, rings, asteroids, much like Deep Impact; I used the term "planet" as a catch-all.

Nevertheless, your point stands, if we consider technologically advanced life a possibility. It would be real shame to clobber someone's moon colony. Perhaps, these impactor missions should not be considered on the first expedition.

Not only would it be rude to pelt someone's colony (or planet) like that, but if they were sufficiently advanced to recognize what's happening, they would likely consider it an attack. Not a great way to make friends.

Anything living on stellar bodies without an atmosphere should be prepared for micrometeorite impacts.

Of course this is a somewhat strange micrometeorite, but it shouldn't be too far from the standard set of space debris.

as far as I understood the starshot discussions, they weren't optimistic about managing to pack any interferometry equipment in such a small package, so there'd be little hope of proper chemical analysis... There was some discussion of what could be figured out from color alone, w/o spectra -- which sounds rather desperate.

A big telescope on earth/in orbit could possibly do more actual work on figuring out stuff about a nearby star than such seconds-long flybys of such wimpy payloads, which is all you get even after you manage the non-trivial challenges of building the phased array, surviving the ISM, establishing communications somehow etc.

Modulate reflections of the light-sail propulsion beam?

at destination? There's no propulsion beam there; all acceleration would have been done at launch, in the vicinity of Earth. You can't point lasers over light-years of distance.

If you have a stream of them going, you can relay the message back through the other ships, until it reaches the origin.

In theory, you can relay messages within any power budget, it's only a matter of reducing the distance between ships.

There's some very interesting work on using the Sun itself as a gravitational lense for sending signals back and forth to the craft, using surprisingly small amounts of power. More writeup here:

http://www.centauri-dreams.org/?p=35486

Really cool! Thanks for sharing.

Seems like there'd need to be a huge amount of effort to set up the transmission point on the other side of alpha centauri, but it sure would be amazing to have stable cheap communications across light years.

I presume this is a part of/sponsored by/ or something related to the Breakthrough Starshot Initiative[0]? It is not mentioned in the article.

[0] https://breakthroughinitiatives.org/Initiative/3

Solar sail technology seems so promising as a means of allowing our species to take our first steps into space. It's a shame that more isn't being put into it, as far as I am aware, the first test on it was done just two years ago.

No, there was testing earlier than that. In particular, a Japanese test in Venus transfer orbit starting in 2010:

https://en.wikipedia.org/wiki/Solar_sail

The one 2 years ago was the Planetary Society's Lightsail, which had a big crowdfunding campaign. The next iteration of Lightsail is launching on the 2nd Falcon Heavy flight.

This is prob a silly idea but is there any way to harness this cosmic radiation that is bombarding the chip? Cosmic rays are high energy particles. Surely we can do something with that right?

High energy but low frequency. 0.1 watts absorbed dose of cosmic rays would kill you in less than a day, and your a lot larger than a chip.

Math: 0.01 J/kg = 1Rad. 1w = 1J/sec. 100kg = 220lb and a reasonable estimate for person. .1w/100kg = 0.10 rads per second, 6 rads per minute, 360rads per hour which is just under the LD/50, but 24h = 8640rads which is just flat out lethal. Though with good care you might last another ~2 very unpleasant days. Of course not all radiation is the same so you can try some equivalent dosages, but no that's not going to save you.

It's enough to fry your hardware but not enough to drive your vehicle with. A bit like a bullet hitting a driving car. If it hits in the right place it would kill the car (or it's occupant(s)), but you can't really propel your car with bullets, not only because there are too few bullets to start counting on but also because they can hit you from any angle when they do hit.

I interpreted that as a question about energy harvesting, not propulsion.

Sounds plausible to me. A sort of, cosmic ray greenhouse effect working on a dense insulated target, producing a heat gradient to a (cosmic ray transparent) radiator.

I'm not sure if the material requirements work out, or if it's worth it's mass to bring along.

This means that here on earth, our new terrestrial robot overlords will be invulnerable to tempest and EMP attacks, after they take our jobs.

But will they be immune to bullet?

No, but who has better reactions? A human or a machine?

Or an extended exposure to electro magnetic radiation?

The ones controlling advanced aircraft will, in some cases, fly faster than most bullets.

Advanced aircraft fly faster than mountains too, but somehow those mountains manage to hit them.

Yes, and flying as fast as a bullet directly into another bullet travelling in the opposite direction means an impact at twice the speed of each.

They'll have better immunity than you.

Reply on news.ycombinator.com