Manned Missions To Jupiter

Dayton Kitchens · 2005-12-14 20:28:03

I can't find anything online about the potential of manned missions to Jupiter and its moons. I don't recall ever seeing one aside from something in Popular Mechanics or Popular Science bacn in the 1980s about a Soviet mission to Callisto that some had planned.

To me, a mission to Callisto (it alone of the Jovian large moons is in a low radiation area) followed by telerobotic exploration from there of Jupiters atmosphere makes alot of sense as a goal in space exploration.

I've read that with nuclear electric propulsion it would take only about 2 years and 73 days (2.2 years) to go one way to Jupiter. How long would a crew have to stay before heading back? What is the overall launch windown like?.

I've been taking a shot at designing a mission architecture though I'm no rocket science. Utilizing a space vehicle similiar to the one disigned for Mars Exploration by Livermore called "Livermores Great Exploration" if I recall correctly. I envision 12 astronauts evenly split between flight crew and scientists.

Anyone with thoughts on exploration of the Jupiter system?

BWhite · 2005-12-14 20:34:51

IMHO, not feasible without serious nuclear power. Propulsion and life support.

Dayton Kitchens · 2005-12-14 20:47:54

IMHO, not feasible without serious nuclear power. Propulsion and life support.

I thought I specified nuclear/electric propulsion.

GCNRevenger · 2005-12-14 20:47:55

A high-end GCNR or mid-high NSWR rocket could do it for about the same difficulty as getting to Mars with chemical or NTR power.

Dayton Kitchens · 2005-12-14 20:58:09

A high-end GCNR or mid-high NSWR rocket could do it for about the same difficulty as getting to Mars with chemical or NTR power.

In English please.

Sorry, but I'm merely a small town history teacher and assistant football coach.

For a 12 man crew, assuming in situ usage of resources on Callisto (ice that is) what would be looking at in terms of one way and total mission times and mass of vehicle leaving Earth orbit?

The vehicle I envisioned involved two habitation/activity areas about the size of shuttle external tanks rotating around a central core so that the crew would have a reasonable level of gravity in sleeping, eating, and exercise areas while the central core would be micro gravity. On the forward end of the core would be the command area where research is conducted, unmanned probes are launched and the spacecraft controlled.

The aft end would have the propulsion system.

GCNRevenger · 2005-12-14 21:54:20

A breif summery of the operation of each engine type:

The efficiency of thermal rocket engines is controlled by how light the fuel is, and how hot you can get the exhaust. With a nuclear engine, you can get going really hot, about as hot as you want (within reason), the problem is getting too hot. If you just take a brick of Uranium oxide/nitride, make it go critical so it gets hot, and use it to boil Hydrogen you can get efficiencies about double of chemical rockets. You can't go any higher then this, because the Uranium brick just plain melts... it does a number on the engine nozzle too.

The GCNR engine solves this problem by putting the Uranium in a 3D "whirlpool" of liquid hydrogen, with extra confinement lent by magnets. In this case, its okay if the Uranium melts and even boils, since it will stay in the engine as dense materials tend to stay in the center of whirlpools. The heat is passed to the surrounding Hydrogen, which boils and is squirted out the back. Efficiencies on the order of ten times chemical fuels are theoretically possible. This is an especially elegant solution to the problem, and has become my namesake.

The NSWR engine is a little bit less exotic... instead of having the nuclear reaction bottled up in an engine, it puts the reaction on the outside of the ship: a solution (Uranium disolved in water) is made so concentrated, that the Uranium in the water would go critical if enough of it came together, a volume big enough, and flash-boil the water to extreme temperatures. The concept is real simple: sqirt the solution out a hole in the back of your rocket and the flash-boiled water gas expands and pushes your rocket. Efficiences as high as twenty times over chemical fuels are possible.

Either type of engine would be easy to refuel with water ice supplies and energy, although the NSWR engine will probobly need more Uranium then a GCNR engine and fuel tank mass will be high since it has to provide neutron absortion and anti-icing heating.

A ship around 2-4 times the size as ones proposed for Mars could make the trip, depending on configuration, could probobly take half a dozen people to Jupiter and back in a few years.

Dayton Kitchens · 2005-12-14 22:48:44

Appreciate it.

Would either engine be continously thrusting?

GCNRevenger · 2005-12-14 22:53:12

By "continuous," it would only fire minutes or hours, not like an ion engine for months at a time. The thrust these engines generate is MASSIVE compared to an electric engine.

Dayton Kitchens · 2005-12-15 07:52:30

By "continuous," it would only fire minutes or hours, not like an ion engine for months at a time. The thrust these engines generate is MASSIVE compared to an electric engine.

Thanks. That is about what I expected.

Where do we stand with the technical capability to build flight ready versions of either engine? And what kind of time frame would we be looking at assuming funding was adequate from program approval to flight readiness?

GCNRevenger · 2005-12-15 12:02:00

I would say a minimum of five years to produce a working model, if we put several billion (like, efficiently, not like Lockheed/Boeing efficient) dollars a year behind it. Ten years to make a "good" engine.

The NSWR engine has the problem of requiring a rather large mass of weapons-grade Uranium, and is extremely dirty. Testing on Earth is unlikly to be acceptable, even by nuke-fanboy me.

The GCNR engine, however, probobly requires advances in materials and fluid dynamics first before it would be practical for propulsion.

RobS · 2005-12-16 00:14:01

A Hohmann (minimum energy, maximum time) trajectory from Earth to Jupiter takes about 2.75 years. This is rather long, but we could design ships to do it. The bigger problem would be to keep the crews from going crazy from confinement so long in a little can. The delta-v (change of velocity) from low Earth orbit is 8.8 km/sec (19,000 mph). From the Earth's surface the delta-v is 14.22 km/sec (32,000 mph). These data come from an old CRC I have at home, which has a chart of Hohmann transfer orbit information from all nine planets to all nine planets.

But a relatively small increase in departure velocity will greatly shorten the travel time. The probe being launched to Pluto next month will travel to Jupiter in a mere one year, and it's using chemical propulsion; even more, the uppermost departure stage is a solid-fueled (low specific impulse) stage! Keep your eye out for information about the departure velocity; it will tell us what velocity could take people to Jupiter in a year. I suspect a solid-core nuclear engine is sufficient, though somewhat on the borderline (just as chemical is sufficient for Mars, but somewhat on the borderline).

The delta-v on arrival to Jupiter could be large or small depending on several factors. One is how close to Jupiter you dare go; if you fire your engines just above Jupiter's clouds, deep inside the gravity well, a very small delta-v (maybe 1 km/sec) will put you into orbit, and you could then get to Callisto using gravity assists by the various moons. But that will take you through the planet's formidable van Allen belts and fry you with radiation unless you're prepared to retreat into a small shelter for days at a time. Circularizing your orbit to Callisto's and landing on Callisto takes maybe 4 km/sec.

You'd need an advanced nuclear reactor on Callisto's surface to make the hydrogen fuel for the return flight; the moon is largely water, so finding hydrogen would not be a problem. You'd need highly reliable life support because the entire trip will be long; let's say 1 year out, 1 year back, and at least 2 years there. I'd send at least two, maybe three independent ships so they could rescue each other, each with 4-6 crew minimum. You also would probably leave the nuclear engines in Callisto orbit, so you'd need chemical engines for landing your hab modules on Callisto and getting them back to orbit, and for launching the hydrogen fuel for the return trip to Callisto orbit. With such a long stay and so many people you'd want a lot of tonnes of stuff along; pressurized roving vehicles for surface exploration, a network of communications satellites around each of the moons, and several telerobotic rovers on each moon to control from Callisto. So it'd be a big operation.

Somewhere I saw, maybe six months ago, a proposal for a mission to Calliso in the 2050-2060 time frame. The allmighty Google should reveal it to you. A Mars mission will develop the autonomous long-term life support systems that come close to meeting your needs for a Callisto mission; closer than the ISS systems match Martian needs. What you need to add is a new propulsion system.

-- RobS

Dayton Kitchens · 2005-12-17 10:27:36

^I agree with virtually everything you posted there except for having two or three independent ships for a rescue capability.

I don't think you can have a serious inspace rescue capability (aside from the Apollo 13 type) without the infrastructure in place for easy access to the area where a disaster might occur.

We don't have a real rescue capabilty right now for earth orbit operations.

We won't have one for the first Mars missions.

So why make it a requirement on a mission to Jupiter?

GCNRevenger · 2005-12-17 11:34:52

The Apollo-XIII disaster was a different case, that the vehicle they were in only needed a fairly modest Delta-V maneuver to get back to Earth in one piece. So would an escape mechanism in Earth orbit, which would only need a little delta for deorbititing. Even a Mars ship could return to Earth in 1.5yrs without signifigant delta... a long time, but not if its either that or death, I'd be happy to live in a tin can for same number of years I planned to anyway.

Jupiter however probobly has no practical free-return trajectory in a reasonable timespan to return to Earth, and would require enough delta for a direct abort. So it makes more sense here then in any historic case to send a second ship. If you have to send a backup propulsion system, you might as well send a whole new backup ship while you are it.

Dayton Kitchens · 2005-12-18 13:13:40

You're probably right.

I wonder if there is broad agreement that for a mission to Jupiter that the manned landing should be on Callisto for reasons of minimizing exposure to the radiation fields near Jupiter.

And I was wondering, how often the launch windows open to and from Jupiter? Wonder if there is some kind of website where you can figure future launch windows to various targets?

GCNRevenger · 2005-12-18 13:51:38

If you were planning on spending much time around Jupiter, then Callisto would probobly be a good place to set up shop. Water ice on the surface, at least some gravity, and the radiation is low enough to walk around in a suit without high energy magnetic or electrostatic shielding.

If you are packing a 5000sec Isp GCNR or NSWR engine, you can probobly leave almost any time during the year you want.

RobS · 2005-12-20 16:09:43

New Horizons will depart Earth’s vicinity at a blistering 8 miles per second, passing the orbit of the Moon in just eight hours

http://www.space.com/missionlaunches/05 … pdate.html

This is the speed of New Horizons after it leaves the Earth's gravity well. That means it has to receive a delta-v of about 6 miles per second (10 km/sec) in low Earth orbit in order to leave Earth at an initial speed of 10.5 miles per second/17 kilometers per second/38,000 miles per hour, the velocity needed to depart the gravity well at 8 miles per second.

That's the velocity you need to reach Jupiter from Earth in one year. Not bad. If one were to launch from L1 using lunar fuel (assuming such fuel were available) and fell into Earth's gravity well to fire one's engine right above the atmosphere, one would need an additional delta-v of 2.5 miles per second/4 km/sec. I bet that would get you to Mars in about 2-3 months. You'd be moving close to solar escape velocity, so it would be almost a straight shot.

-- RobS

Austin Stanley · 2005-12-21 00:38:54

The only problem then, is trying to stop. You would be going way to fast to safely aerobreak into Martian orbit. So at least some propulsive breaking would be necessary. And for the Jupiter mission, I don't think the crazies would be happy with a Nuclear Engine starting up so close to Earth's atmosphere, but then again, we don't have to tell them do we. Since the exhaust would all be moving at a greater than escape velocity, it shouldn't be to much of an issue.

GCNRevenger · 2005-12-21 07:36:29

When you have an engine this powerful, and you have big low-density fuel tanks needed to carry Hydrogen for it, you don't need no aerobrakin'

If we can't keep the "oh no! its nuclear, we're all gonna DIE" crowd in check, we aren't going anywhere anyway.

RobS · 2005-12-21 14:48:23

According to Zubrin's *The Case for Mars,* aerobraking is good only for trips to Mars of more than 130 or 140 days. If you get there faster than that, you scream through the thin atmosphere too fast to slow effectively.

If gas-core nuclear engines emit highly radioactive exhaust (or even highly corrosive hydrogen plasma), your problem doesn't come from proximity to Earth; presumably you fire the engines when they aren't pointed in that direction anyway. Your problem comes from any satellites that might get caught in the exhaust. It may be that the exhaust plume spreads out pretty wide by the time it reaches geosynchronous altitude and possibly it would damage satellites (especially their arrays or dishes) or make them radioactive (and therefore dangerous to capture and repair, if we are doing a lot of satellite repair by then). But avoiding the geosynchronous "band" of satellites around the equator wouldn't be hard. Making sure you don't damage one of the thousands of satellites in low or middle earth orbit might be more complicated.

-- RobS

GCNRevenger · 2005-12-21 17:44:43

Nonsense

The sky is a very, very big place and the exhaust plume will disapate; its still just a rocket engine, albeit one with high exhaust velocity.

Second, the exhaust from a GCNR engine won't be "highly radioactive" because the nuclear fuel will stay inside the core for the most part. Its probobly possible to recover the bulk of the core while it is in a liquid state after firing.

Hydrogen plasmas will rapidly cool in space and reform molecular Hydrogen too.

Commodore · 2005-12-21 20:10:19

Hydrogen plasmas will rapidly cool in space and reform molecular Hydrogen too.

Does that mean there is going to be clouds of hydrogen were ever we fire one of these off?

GCNRevenger · 2005-12-21 20:19:06

For a fleeting moment behind the ship before it dissapates into the vacuum of space? No more than water vapor from a Hydrogen/Oxygen rocket does, except it will disapate much faster.

The nozzle might look a little something like this during firing:

Or

Commodore · 2005-12-21 20:52:36

Yeah but its not just going to scatter evenly around the universe. Its going to go were whatever forces send it. Enless that means directly into the atmosphere, that means its going to float around somewhere in abnormally high concentrations.

In any event, heres Nasa's Human Outer Planet Exploration (HOPE) Mission plan to Callisto info someone mentioned: PDF (3.1MB)

Its seems like a good plan for what it sets out to do. But if you going all that way, you aught to take the time to find ways to open up the rest of the Jovian system to human exploration by testing various methods of radiation shielding.

John Creighton · 2005-12-21 22:07:39

Yeah but its not just going to scatter evenly around the universe. Its going to go were whatever forces send it. Enless that means directly into the atmosphere, that means its going to float around somewhere in abnormally high concentrations.
In any event, heres Nasa's Human Outer Planet Exploration (HOPE) Mission plan to Callisto info someone mentioned: PDF (3.1MB)
Its seems like a good plan for what it sets out to do. But if you going all that way, you aught to take the time to find ways to open up the rest of the Jovian system to human exploration by testing various methods of radiation shielding.

Not true. The solar wind carries away free hydrogen ellements.

Commodore · 2005-12-21 23:10:49

In a predictable pattern no doubt.

New Mars Forums

Announcement

#1 2005-12-14 20:28:03

Re: Manned Missions To Jupiter

#2 2005-12-14 20:34:51

Re: Manned Missions To Jupiter

#3 2005-12-14 20:47:54

Re: Manned Missions To Jupiter

#4 2005-12-14 20:47:55

Re: Manned Missions To Jupiter

#5 2005-12-14 20:58:09

Re: Manned Missions To Jupiter

#6 2005-12-14 21:54:20

Re: Manned Missions To Jupiter

#7 2005-12-14 22:48:44

Re: Manned Missions To Jupiter

#8 2005-12-14 22:53:12

Re: Manned Missions To Jupiter

#9 2005-12-15 07:52:30

Re: Manned Missions To Jupiter

#10 2005-12-15 12:02:00

Re: Manned Missions To Jupiter

#11 2005-12-16 00:14:01

Re: Manned Missions To Jupiter

#12 2005-12-17 10:27:36

Re: Manned Missions To Jupiter

#13 2005-12-17 11:34:52

Re: Manned Missions To Jupiter

#14 2005-12-18 13:13:40

Re: Manned Missions To Jupiter

#15 2005-12-18 13:51:38

Re: Manned Missions To Jupiter

#16 2005-12-20 16:09:43

Re: Manned Missions To Jupiter

#17 2005-12-21 00:38:54

Re: Manned Missions To Jupiter

#18 2005-12-21 07:36:29

Re: Manned Missions To Jupiter

#19 2005-12-21 14:48:23

Re: Manned Missions To Jupiter

#20 2005-12-21 17:44:43

Re: Manned Missions To Jupiter

#21 2005-12-21 20:10:19

Re: Manned Missions To Jupiter

#22 2005-12-21 20:19:06

Re: Manned Missions To Jupiter

#23 2005-12-21 20:52:36

Re: Manned Missions To Jupiter

#24 2005-12-21 22:07:39

Re: Manned Missions To Jupiter

#25 2005-12-21 23:10:49

Re: Manned Missions To Jupiter

Board footer