Callisto. A thread devoted to the most human survivable Galilean Moon

Oldfart1939 · 2024-05-09 17:18:31

IMHO, using solar power on Callisto is really an exercise in futility. As we get further from the Sun, more dependance will be on using nuclear energy. Even on Mars, the irradiance is bordering on too low to make effective use thereof...

Void · 2024-05-09 19:57:10

Nuclear is an option to consider, I think especially on starting settlements.

Done

Oldfart1939 · 2024-05-14 12:51:16

Here's the link to an excellent and short report on a NASA study for the exploration of Callisto. It utilizes thermonuclear propulsion to get there and has a 250 KW nuclear reactor included.

https://www.youtube.com/watch?v=QG-8jZs … WL&index=2

Mars_B4_Moon · 2024-05-15 13:32:30

From previous threads the Chinese might have a Tianwen-4 also known in some news reports the Gan De a planned Chinese twined interplanetary mission to study the Jovian system and something else, maybe one probe or spacecraft studying Ganymede or 'Callisto' or another possibly sharing a launch with a spacecraft which will make a flyby of Neptune or Uranus or maybe study a Moon of one of these bodies.

'Callisto Landing'?
https://www.planetary.org/articles/jupi … to-landing

four deep space exploration missions before 2030, including probes to Mars, asteroids and Jupiter
https://web.archive.org/web/20180425130 … 136188.htm

See EuropaClipper one last time before it leaves JPL and heads to NASAKennedy to prepare for launch.
https://twitter.com/NASAJPL/status/1790783717239296198

Another mission is en route by ESA already launched by the European Space Agency (ESA), from Guiana Space Centre in French Guiana South America.

Oldfart1939 · 2024-10-23 16:55:05

Now that Europa Clipper has successfully launched, as has the ESA Icy Moons "Juice" probe, we can all sit back and age gracefully for 6 years until Europa Clipper arrives in the Jovian system. We should definitely learn a LOT from these 2 probes, and EC has flybys of both Ganymede and Callisto included in their mission profiles.

GW Johnson · 2024-10-25 09:11:53

I'm sitting here wondering why this trip is taking 6 years 1-way?

A simple Hohmann min energy transfer ellipse has a 1-way travel time of 2.9 years at worst case for longest time, which is half the period of the ellipse. The shortest time goes with the highest velocity "far" from the Earth of some 39.14 km/s with respect to the sun.

Earth averages around 29.77 km/s with respect to the sun (max 30.27, min 29.28), subtracting that gets you a figure for the velocity "far" from the Earth that you need to achieve with respect to the Earth: about 9.37 km/s, give or take a small snit.

Using about 10.9 km/s Earth escape velocity at the altitude of LEO, we can estimate the required "near" velocity with respect to the Earth, which is the actual speed needed at end of burn to get onto that transfer ellipse about the sun. That figures as about 14.4 km/s. You figure that as the square root of the sum of needed speed-squared plus escape speed-squared. It's a conserved mechanical energy thing.

If one departs from LEO in order to get the right timing and angle geometries, LEO speed is close to 7.8 km/s. The difference is your delta-vee required to depart from orbit onto the interplanetary trajectory: 6.6 km/s. If a LOX-LH2 departure stage, the stage mass ratio is about 4.47, or about 78 or 79% propellant mass fraction, which is quite doable. At ~5% stage inert fraction, that leaves about 16 or 17% stage payload mass fraction (nice and generous!), which would be the mass of the probe. Big probe is a big stage, that's the rub. Probe+stage ignition mass is the payload you have to orbit with your launch rocket.

Online, I found a mass figure for the Europa Clipper probe: 3.241 metric tons. The probe plus loaded stage should be 3.241 mt/0.165 (for 16.5% payload fraction), = ~ 19.6 metric tons. Falcon-9 can orbit that, certainly Falcon-Heavy can. Even Atlas-5 could, with all the SRB's installed. So why are we spending 6 years to get there when we could do it in 3? Of course, that online mass figure could be wrong. Stage+probe mass would scale in proportion to probe mass. Regardless, Falcon-Heavy is supposedly capable of sending 63 tons to orbit, although not reusably.

Sounds to me like they're using too small a launch rocket, for the size of the probe and its required departure stage. They have to do gravity assists to get onto the right trajectory with too small a rocket. Gravity assist maneuvers cost you years of flight time. The Sergei P. Korolev solution to this dilemma was just to build a bigger rocket, which is where the workhorse R-7 (that everybody calls a Soyuz) came from, more than 60 years ago.

BTW, SpaceX is attempting EXACTLY that "Korolev bigger rocket solution" with its Starship/Superheavy. That orbit transport function is really what the big rocket is all about. You actually have to misuse it to fly to Mars in it. It's big enough to do that, though.

GW

Last edited by GW Johnson (2024-10-25 09:29:24)

Oldfart1939 · 2024-11-15 15:44:11

GW--
I did a Google search to determine the as-launched mass of Europa Clipper, and it's approximately 6,000 kg. The dry mass is 3,241 kg. The difference is fuel mass, 2,750 kg, to be used for flight path corrections and orbital insertion.

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#26 2024-05-09 17:18:31

Re: Callisto. A thread devoted to the most human survivable Galilean Moon

#27 2024-05-09 19:57:10

Re: Callisto. A thread devoted to the most human survivable Galilean Moon

#28 2024-05-14 12:51:16

Re: Callisto. A thread devoted to the most human survivable Galilean Moon

#29 2024-05-15 13:32:30

Re: Callisto. A thread devoted to the most human survivable Galilean Moon

#30 2024-10-23 16:55:05

Re: Callisto. A thread devoted to the most human survivable Galilean Moon

#31 2024-10-25 09:11:53

Re: Callisto. A thread devoted to the most human survivable Galilean Moon

#32 2024-11-15 15:44:11

Re: Callisto. A thread devoted to the most human survivable Galilean Moon

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