What’s Titan look like this time of year?
https://youtube.com/watch?v=lZa83dTf4JA
Exciting to see reality (almost) following fiction. Gattaca is an excellent film, if you haven’t seen it.
NASA plans to launch a spacecraft to Titan
51–60 of 197 posts
Re: NASA plans to launch a spacecraft to Titan
#52A 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…
In addition to lack of solar energy, I wonder if nuclear power source is necessary to keep batteries or other electronics warm enough to function properly. Conversely, on Titan, we won't need to worry about heat sinks as everything is kept at ~94K in a bath of liquid and frozen methane. Perhaps in a few hundred years AWS's most popular region for intensive compute will be under Titan's methane sea. High spin up cost,…
Hah, I was always intrigued by the idea of placing solar cells on the bright side of Mercury and servers on the dark side. I wonder what other good options might exist in the solar system.
Re: NASA plans to launch a spacecraft to Titan
#53> Scientists suspect that Titan might even have water—real, actual H2O—lurking beneath its surface. Not just a little, but a lot of water: > The density of Titan is consistent with a body that is about 60% rock and 40% water. > ... > Pre-Cassini models of impact trajectories and angles suggest that where the impactor strikes the water ice crust, a small amount of ejecta remains as liquid water within the crater. It m…
> The density of Titan is consistent with a body that is about 60% rock and 40% water.
That's extremely misleading.
First, rocks have different densities. Sandstone weighs 2g/cc, basalt weighs 3g/cc, so a density "consistent with" 50% basalt, 50% water would be equally consistent with 100% sandstone, not to mention the possibilities of rocks with drastically different densities such as pumice or iron.
Secondly, we are pretty certain Titan has large quantities of liquid methane and/or ethane (check the same Wikipedia link) which certainly account for some of the difference in density between Titan and other rocky bodies.
So yes, there is water on Titan, but it's about as likely to be 40% water as it is to be 40% cheese or 40% iPhones, even if its density suggests a makeup consistent with that.
Re: NASA plans to launch a spacecraft to Titan
#54A 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…
In addition to lack of solar energy, I wonder if nuclear power source is necessary to keep batteries or other electronics warm enough to function properly. Conversely, on Titan, we won't need to worry about heat sinks as everything is kept at ~94K in a bath of liquid and frozen methane. Perhaps in a few hundred years AWS's most popular region for intensive compute will be under Titan's methane sea. High spin up cost,…
Well we don't want to disturb the environment too much
Re: NASA plans to launch a spacecraft to Titan
#55Earlier quoted context omitted.
Will this be the first-ever instance of nuclear-powered flight?
No. >> The Pentagon is aware of a Russian test of a nuclear-powered cruise missile but the system is still under development and had crashed in the Arctic in 2017.[17][18][19] A RAND Corporation researcher specializing in Russia said "My guess is they're not bluffing, that they've flight-tested this thing. But that's incredible." https://en.wikipedia.org/wiki/Nuclear-powered_aircraft#Russi... https://en.wikipedia.org…
Why bother? Rocket fuel is cheaper than nuclear fuel and rocket missiles can already hit anywhere.
Re: NASA plans to launch a spacecraft to Titan
#56Earlier quoted context omitted.
Maybe answering my own question with some further thought. I guess even if it could get there, it likely couldnt return which would be a big waste of a reusable starship.
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 basis he thinks Starship might be able to get there in the first place.
Re: NASA plans to launch a spacecraft to Titan
#57Earlier quoted context omitted.
In addition to lack of solar energy, I wonder if nuclear power source is necessary to keep batteries or other electronics warm enough to function properly. Conversely, on Titan, we won't need to worry about heat sinks as everything is kept at ~94K in a bath of liquid and frozen methane. Perhaps in a few hundred years AWS's most popular region for intensive compute will be under Titan's methane sea. High spin up cost,…
Hah, I was always intrigued by the idea of placing solar cells on the bright side of Mercury and servers on the dark side. I wonder what other good options might exist in the solar system.
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.
Re: NASA plans to launch a spacecraft to Titan
#58A 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…
What about hydrogen fuel cells? Isn't the whole place basically nothing but fuel?
Re: NASA plans to launch a spacecraft to Titan
#59Earlier quoted context omitted.
No. >> The Pentagon is aware of a Russian test of a nuclear-powered cruise missile but the system is still under development and had crashed in the Arctic in 2017.[17][18][19] A RAND Corporation researcher specializing in Russia said "My guess is they're not bluffing, that they've flight-tested this thing. But that's incredible." https://en.wikipedia.org/wiki/Nuclear-powered_aircraft#Russi... https://en.wikipedia.org…
Why bother? Rocket fuel is cheaper than nuclear fuel and rocket missiles can already hit anywhere.
Maybe so it can double as a shitty nuclear bomb. I'm gonna crash my small nuclear reactor into you.
Re: NASA plans to launch a spacecraft to Titan
#60I love this mission. From a science point of view it’s probably good to send similar and well tested rovers to Mars. But to me it gets boring. I think NASA used to get a lot of fascination from doing the seemingly impossible like flying to the moon. So I think a mission like this will be fascinating for a lot of people. Also it may spawn off a lot of technology. I hope for a submarine mission to Europa.
I think a flying mission is actually superior to a rover as it can cover far more ground and reach some sites that wouldn't be feasible for a rover. And Titan is uniquely suited to using flight to explore as its gravity is a factor 7.25 lower and its atmosphere a factor of 4.4x denser. That means it's about 30 times easier to hover and covering the same distance is at least 7 times as efficient as on Earth, besides having lower terminal velocity.
Even this relatively "inefficient" quadcopter (8 rotor) design could cover dozens of miles (~60km, more than any Mars rover has ever done in its entire mission) in a single hop (which could be recharged by the MMRTG in a single week-long night), although prudence suggests shorter hops at first. That means in principle over its ~10 year lifespan (assuming it can last as long as Cassini did...) it could nearly circumnavigate the entire planet (diameter of ~5000km, day period of about 16 Earth days) while visiting dozens of sites. Granted, range will likely be much more modest as the mission operators will be focusing on not losing this valuable asset, but it shows just how powerful the ability to fly could be. It can visit more sites than all the surface robotic missions to Mars combined. In that sense, it's a fantastic scientific value. And I think the public will absolutely love it.
Information from the Dragonfly proposal document: http://dragonfly.jhuapl.edu/News-and-Resources/docs/34_03-Lo...