NASA plans to launch a spacecraft to Titan • Hacker News Board

Re: NASA plans to launch a spacecraft to Titan

#181

Post by dredmorbius » Sat, Jun 29, 2019, 4:58 PM UTC

tericho wrote: post #102

disconnected wrote: post #96

Earlier quoted context omitted.

To put it into perspective: https://solarsystem.nasa.gov/moons/saturn-moons/titan/overvi... According to this (at the time of reading) a one way trip at the speed of light is ~75 minutes, so you will have approximately two and a half hours of ping. Ouch. Still, it raises an interesting question: how would a hypothetical Earth-Titan network protocol work?

Can't do much about the time it takes light to get here, so I guess the answer is we'd have to learn to love 75 minute ping :)

If you can't be with the one you ping, ping the one you're with.

Re: NASA plans to launch a spacecraft to Titan

#182

Post by sandworm101 » Sat, Jun 29, 2019, 5:37 PM UTC

pault wrote: post #131

nickserv wrote: post #47

Earlier quoted context omitted.

This case is different though, using the fission reaction to generate electricity which in turn powers the electric motors among other things. The nuclear powered missiles use the fission reaction to heat incoming air similar to how a jet engine works.

Does that mean a nuclear powered cruise missile could stay airborne until mechanical failure? That would make future warfare... interesting.

It isn't all that much of a game changer. Mid-air refueling means that bombers can stay airborne a long time. Four or five bombers rotating back and forth can maintain one "on station" continuously. So the capability is already there. This tech would just make it more scifi.

Re: NASA plans to launch a spacecraft to Titan

#183

Post by rhacker » Sat, Jun 29, 2019, 5:45 PM UTC

They are planning to send it up in 2026? What are they going to be doing for 6+ years?

Re: NASA plans to launch a spacecraft to Titan

#184

Post by asteli » Sat, Jun 29, 2019, 6:50 PM UTC

rhacker wrote: post #183

They are planning to send it up in 2026? What are they going to be doing for 6+ years?

They just announced it today. They don't have a probe yet. They have to design and build and test all of the equipment and systems that are going to go into space. I think it's pretty reasonable for this to take 6 years.

Re: NASA plans to launch a spacecraft to Titan

#185

Post by pcnix » Sun, Jun 30, 2019, 1:31 PM UTC

MereInterest wrote: post #80

AnIdiotOnTheNet wrote: post #57

Earlier quoted context omitted.

Mercury's whisper thin atmosphere won't be much use for cooling anything, though possibly the surface would be. However, the real problem is that Mercury isn't actually tidally locked anyway.

You could have the facility move constantly to keep the facility straddled across the sunlight line. At the equator, this would require constantly moving at about 7 mph, though you could reduce the speed necessary by moving to higher latitudes.

Also appears in Asimov's classic "I, Robot" collection, as a Powell and Donovan story called "Runaround"[1].

[1]: https://en.wikipedia.org/wiki/Runaround_(story)

Re: NASA plans to launch a spacecraft to Titan

#186

Post by sq_ » Sun, Jun 30, 2019, 6:49 PM UTC

pault wrote: post #129

aeorgnoieang wrote: post #81

Earlier quoted context omitted.

In a sense tho, at-the-speed-of-light is real time, as it's the maximum speed of anything.

If, as clock A nears the speed of light it appears that stationary clock B is slowing down, doesn't that mean that at the speed of light is no time? Does a photon in a vacuum arrive instantly at its destination? If a photon looks at another photon, does the other photon appear not to be moving at all, or... Ouch my brain.

Not completely related, but you reminded me of something interesting I remember hearing about neutrinos. Apparently (HN physicists please correct me if I'm wrong), neutrinos have an extraordinarily tiny objective lifetime, and the only reason we can detect them is that, because they travel so close to the speed of light, they experience almost no passage of time in while in flight.

Re: NASA plans to launch a spacecraft to Titan

#187

Post by anticensor » Sun, Jun 30, 2019, 9:45 PM UTC

martinald wrote: post #151

garmaine wrote: post #134

Earlier quoted context omitted.

These are physical restrictions, not technological.

What about the laser technology NASA is developing? That should be a lot faster than current radio based technology?

You will need a blinding-strong laser.

Re: NASA plans to launch a spacecraft to Titan

#188

Post by knd775 » Mon, Jul 01, 2019, 4:12 AM UTC

caconym_ wrote: post #56

knd775 wrote: post #39

Earlier quoted context omitted.

Why do you think it would be unable to return? I'm curious.

Naively, a round trip requires twice the delta-v, which means you need to launch with a lot more than twice the fuel. Maybe they could produce more fuel and oxidizer in situ, and maybe Earth is a more attractive target for aerocapture, and maybe gravity assists line up better one way or the other, but it's not a bad starting point to assume a round trip is far more expensive than a one-way trip. I'm not sure on what…

Sorry for the late reply. Titan has lakes of liquid methane rather than water. Raptor is a methalox engine. I think refueling on the planet would be quite possible.

Re: NASA plans to launch a spacecraft to Titan

#189

Post by andygates » Mon, Jul 01, 2019, 9:58 AM UTC

bdamm wrote: post #124

swebs wrote: post #121

Earlier quoted context omitted.

There will be at least an hour delay. Saturn is pretty far

10 seconds of video from Titan would change the world. It's shame we don't have this from Mars already. So it would take a few weeks to transmit - we got time. Now figuring out which 10 seconds to select and send to earth... that'll be interesting. An on-board cache of x GB data storage, with key frames taken every 30 minutes, would probably be able to select some pretty compelling 10 second segments.

Send them all, just pick a likely-nice one for sending while the eyes of the world are on Mission Control.

Caching everything then sending it at leisure is working nicely for New Horizons.

Re: NASA plans to launch a spacecraft to Titan

#190

Post by andygates » Mon, Jul 01, 2019, 10:03 AM UTC

samstave wrote: post #135

rzimmerman wrote: post #4

A flying drone is a really solid idea for a Titan lander for a couple reasons: * The surface atmosphere density is higher than Earth's (1.5 atm) * Gravitational force is much lower (0.15g) * We don't know a lot about the surface composition or topography, so wheels and motors represent a challenge * Visibility may be poor, making visual navigation tricky (though that's also a problem for a flying vehicle I suppose) I…

Why arent we just mass launching probes to all the planets? Serious question: Why is it not OK to have a standard sensor array on every planet in the solar system?

To the second question: since each mission is expensive and time-consuming, scientists reasonably want the best sensors for each mission.

That's both the tech upgrade during the n-year coast phase, and the investigation upgrade as they work out new things to investigate.

It's not as straightforward as spamming the system with cameras. That's bound to happen more, after the MarCO cubesats had success flying along with Insight.