[poundofshrimp]

> The Europa Clipper will not orbit Europa, but instead orbit Jupiter and conduct 44 flybys of Europa at altitudes from 25 to 2,700 km (16 to 1,678 mi) each during its 3.5-year mission.[…] The Europa Clipper could conceivably flyby at low altitude through the plumes of water vapor erupting from the moon's ice crust, thus sampling its subsurface ocean without having to land on the surface and drill through the ice.

Excitingly, this seems to be a real opportunity for the Europa Clipper mission.

Source: https://en.wikipedia.org/wiki/Europa_Clipper

[TaylorAlexander]

Arriving in April 2030 oof Jupiter is so far away. I hope the next generation of heavy lift vehicles allows for shorter transit to the outer planets.

[adrianN]

I'm a bit sad that we didn't pursue nuclear propulsion for interplanetary missions. A nuclear rocket could reach Jupiter much faster.

[raylad]

It was developed and ready to be flown, but the project was canceled.

https://en.wikipedia.org/wiki/NERVA#NERVA_XE

Recently, work has started up again, and two companies have active contracts to begin developing nuclear engines:

https://en.wikipedia.org/wiki/Nuclear_thermal_rocket#Current...

[antupis]

How safely we can ship nuclear rocket to deep space. That kinda rocket exploding at launch and basically turning dirty bomb could cause some nasty damage to enviroment and would be pr disaster.

[swiley]

Meh, we've put plenty of various kinds of nuclear reactors in space.

[m4rtink]

Also if you don't activate the reactor until after launch the fuel is still effectively just heavy metal.

[ianai]

Or even build it out there. Ie launch mostly pre built components. A ship that never has to worry about first leaving earths gravity well can have vastly different characteristics than something we’d launch from here.

[NikolaeVarius]

Do you really think nobody thinks of these issues?

[arisAlexis]

Imagine detonating nuclear bombs in the atmosphere on purpose. Oops, we did it already.

[papito]

The newer Mars rovers use nuclear power, although obviously, not the same type needed for propulsion.

[bserge]

People are afraid of nuclear power plants. You think they'd ever allow nuclear space flight?

Think of the 0.05% chance of launch failure, all that radioactive shit spread in the air, alongside all the other dangerous shit we already put there willingly!

[WJW]

This would have been a much more convincing argument if we had not already launched several nuclear reactors into space.

[cesarb]

> if we had not already launched several nuclear reactors into space.

AFAIK, we haven't. What we have launched several of are RTGs, which other than using nuclear fuel, are a completely different technology, one which is much easier to completely shield. IIRC, there have even been cases where a rocket containing a RTG failed, and the RTG was found intact and could even be reused.

[perl4ever]

>AFAIK, we haven't

From Wikipedia, there are (or were) over 30 reactor (not RTG) powered satellites. One program was called "US-A" and another "SNAP-10A". These were launched at least from the 1960s through the 1980s, by multiple countries.

"The US-A programme was responsible for orbiting a total of 33 nuclear reactors"

"Normally the nuclear reactor cores were ejected into high orbit (a so-called "disposal orbit") at the end of the mission, but there were several failure incidents, some of which resulted in radioactive material re-entering the Earth's atmosphere."

"The higher-orbiting TOPAZ-containing satellites were the major source of orbital contamination for satellites that sensed gamma-rays for astronomical and security purposes, as radioisotope thermoelectric generators (RTGs) do not generate significant gamma radiation as compared with unshielded satellite fission reactors"

https://en.wikipedia.org/wiki/US-A

"The [SNAP-10A] reactor measures 39.62 cm (15.6 in) long, 22.4 cm (8.8 in) diameter and holds 37 fuel rods containing 235U as uranium-zirconium-hydride fuel.[15] The SNAP-10A reactor was designed for a thermal power output of 30 kW and unshielded weighs 650 lb (290 kg)"

https://en.wikipedia.org/wiki/SNAP-10A

[WJW]

Sure, but the (perceived) popular resistance is to the risks of launching nuclear material, and that is no less for RTGs than for "real" reactors.

Nobody would be all that upset about launching an unfueled reactor, since that is basically just a collection of pumps and turbines not fundamentally different from anything we already shoot up. You could/should even launch the fuel and reactor in different rockets, so that you have more mass budget for wrapping up the fuel rods extra safely.

[bserge]

I was being sarcastic. I mean ffs, the risk averseness has reached ridiculous levels.

[perl4ever]

AFAIK, it's been done, though. Not RTGs, actual reactors. They've been launched into orbit, deorbited and disintegrated in the atmosphere, and blown up in orbit spreading radioactive debris there.

Not one or two launches, but dozens. So there definitely is a risk, but it was once considered acceptable.

[adrianN]

Yes there are very good reasons not to put 10000 nukes on a ship and try to launch it. But it would be extremely cool to have manned missions to the gas giants and to send probes to nearby stars. I don't see how that will be possible without nuclear propulsion.

[robbedpeter]

Asteroid mining first - we will need processing and refinement infrastructure in space, to start building facilities that aren't in earth orbit, so they don't pose radioactive threats. It's thought that there is a lot of uranium and other nuclear fuels available in asteroids throughout the solar system.

Once asteroid mining kicks off, all sorts of possibilities open up that are overly expensive or dangerous for earth based enterprises.

[ianai]

Totally. I wonder about turning larger asteroid(s) into colonies/ships themselves. There’s one large one that already orbits between mars and the outer planets with a sizable radius. I wonder about hollowing it out and building essentially a large city in its interior.

Edit-I think it’s 1036 Ganymed.

[Valgrim]

I'd like to share an interesting read about the prospect of a nuclear-powered Starship. (http://toughsf.blogspot.com/2021/10/nuclear-conversion-for-s...)

Basically, it's not much about safety, it's also that the benefits of nuclear are marginal compared to what the Starship is already capable of, and in many mission configurations, it's actually worse.

[mrfusion]

There are lots of ways to protect the fuel. And beyond that you can launch over the ocean on a day the winds are blowing out to sea and completely protect populated areas.

[wcoenen]

As far as I understand, the next generation of heavy lift vehicles (i.e. Starship, New Glenn, SLS) will not allow us to do better than a Hohmann transfer. And that would still mean waiting for the launch window to Jupiter (period 1.1 years) and a transfer of 3.7 years. So Clipper's cruise of 5.5 years really isn't so bad.

Future space probes will likely continue to save delta-v by taking a slightly slower trajectory with gravity assists.

[mrfusion]

Starship could open up a lot of options. There’s no reason it couldn’t launch a small probe loaded to the gills with fuel and engines and make a shorter trip.

[baq]

Just imagine getting a 90 ton kick stage for a 500kg probe like New Horizons.

[TaylorAlexander]

Interesting. Even with orbital refueling of starship?

[WJW]

Hohmann transfers (the most efficient path) take a fixed amount of delta-V, so how much fuel you have does not really matter. You could probably find a quicker path if you are willing to sacrifice some efficiency, but even then it is going to take several years to get there with current technology. Since probes don't really care about travel time, might as well take the most efficient path so that you have fuel left over for interesting maneuvers near the destination.

[Valgrim]

Or more interesting probes, such as deep-drilling equipment

[profmonocle]

Reminds me of watching New Horizons launch as a High School junior, then excitedly watching the images come in when I was in my mid-20's.

Really drives home how unbelievably vast astronomical distances are, even just within our one solar system. One of the fastest objects humanity has ever built, and it took more than a third of my life to reach its destination.

[EdwardDiego]

And by not landing on the ice, we won't risk angering Star Child Dave Bowman.