MatterBeam

Real research, such as the Human Outer Planet Exploration study (HOPE: Article, Wiki), points to Callisto. Fiction usually focuses on arid Mars or thick-atmosphered Titan, which are lesser candidates. One fact I haven't seen picked up is that Callisto contains large deposits or rock and metal just sitting in the ice like Swiss cheese. For protection against radiation, just stay far away from Jupiter itself. Ganymede's equator is protected by a weak magnetic field, and Callisto is far away enough, that radiation levels fall to 1 rem per day. We naturally get 300 rem per year, and astronauts are allowed up to 25 rem per mission. All in all, a Jovian inhabitant can work a full business year outside of his or her habitat without being worse off than in the ISS. You Camwise logs is always interesting, and I look forward to an... ah, colonization attempt.... of Jupiter? Sorry, this is a mistake and I'll have it corrected shortly. Thanks for picking it up! Vacuum balloons have been proposed, but calculations show that they'd need super-strong carbon-nanotube or graphene-based walls to survive 1 bar of pressure. I suppose they could work in the much thinner upper atmosphere... but consider this: bouyancy is the difference in density. Even if your internal density is 0 (vacuum), the external density is still very low. It might never be practical to build such balloons, even if the super-materials exist.

Hi! I've got a series running on my ToughSF blog where I describe the how and why of living on other planets. The latest entry is for our largest Gas Giant and its 67 moons. How to Live on Other Planets: Jupiter A look at how we could colonize Jupiter and its Moon. Fittingly long for our largest planet! Description Jupiter is big. It masses more than twice of all the other planets combined. Appropriately, it has the lion's share of the moons in our solar system: 67 as of today's count. A faint planetary ring crowns this behemoth. Layered like a big hydrogen snowball. In interstellar terms, Jupiter is a rather average gas giant. It is mostly hydrogen, with about 25% helium and rare traces of other elements. The only solid surface is its core of metallic hydrogen, kept at the crushing pressure of 200GPa. Further extremes are reached at the centre of the planet. The upper atmosphere is more interesting. A mix of ammonia, water and even some sulphides makes for a diverse colour palette. The 1 bar (100000 Pascal pressure) 'surface' of Jupiter is at a hot 67 degrees Celsius. The top of the atmosphere, at 1000km altitude, is so hot that it glows during the night. In between are multiple layers of frigid hydrogen gas. Unlike most planets, Jupiter has a very dynamic cloud and storm system. It is powered by the rotation of the planet, thereby moving clouds at over 45000km/h. The Great Red Spot is one of the largest features, at 12000km tall and up to 40000km wide. These features are even more impressive from the view point of Jupiter's moons. The largest are called the Galilean moons: Io, Europa, Ganymede, and Callisto. All but Europa are larger than our Moon, and two are larger than Mercury. Jupiter follows the 'orbital spaghetti' school of moon systems Accompanying these moons are a plethora of smaller bodies, such as Amalthea (167km), Himalia (170km) and Thebe (100km). Habitability Living on Jupiter's solid surface is not possible. The transition to metallic hydrogen that creates a solid surface involves temperatures and pressures that no habitat or spacecraft can resist. It might be possible, however, to float in the upper atmosphere. Jupiter will offer titanic vertical landscapes. Generating lift will be difficult. Filling balloons with the lightest gasses, such as hydrogen and helium, will not work as the atmosphere is already composed of those same gasses. A 'lighter than air' balloon does not exist here! The problem is compounded by Jupiter's gravity: 2.5G. This means that you would need to produce much more lift than on Earth. The only solutions to generating lift would require the continuous use of energy: hot gasses are less dense than cold gasses, so something like a hot air balloon would work. A quick calculation tells us that if we try to maintain the altitude where pressure is 1 bar (Earth's sea level pressure) on Jupiter, the temperature is about 180 to 200K and density is 0.16kg/m^3. If we can heat up the air inside a hot air balloon to a blistering 450K (the maximum safe temperature of Kevlar), the density inside the balloon would be 0.08kg/m^3. This would provide a terrible lift to volume ratio of 1kg per 12.5m^3 of hot gas. In comparison, a helium balloon on Earth provides 1kg of lift per 0.9m^3. Even then, most of the lift capacity on Jupiter would be lost to the heavy insulation the balloon would require. The other option would be mechanical lift: helicopter blades or wings. Obviously, these cannot be made large enough to support a large habitation base. With the Jovian atmosphere nearly eight times less dense than our atmosphere and with 2.5 times more gravity, an airplane would have to travel twenty times faster to take off, or require wings twenty times bigger and heavier. Hypersonic... at liftoff? Something like a 737-800 would have to travel at 7500km/h (Mach 6) to stay in the air! Even if hopeful colonists manage to stay in the air, they will find themselves in the Jovian equivalent of a desert: no useful volatiles, poor energy resources and exacting living conditions. Jupiter's atmosphere is starved of water and oxygen-containing compounds. They, along with elements such as sulfur or nitrogen, are held in the lower atmosphere, where pressures of 10 bars or greater make their extraction difficult. Considering the issues with generating lift and finding resources, habitats on Jupiter would have to stay very deep in the atmosphere. There, they trade crushing pressures and high temperatures for denser air and access to wispy clouds of ammonia and water. At least, at those depths, the habitats would not have to worry about radiation hazards or meteorites. These same hazards make living in close orbit around Jupiter very hazardous. Automated factories would suffer from rapid degradation of their electronics, so even an unmanned presence is unsustainable. Moons of interest Living in or around Jupiter does not seem to be worthwhile, at least with conceivable technology. Staying on one of the moons orbiting the gas giant would be the better deal... but which of the moons is the most promising target for colonisation? We will look at the Galilean moons first. Together, they represent 99.997% of the mass orbiting Jupiter. Io Io is the Galilean moon orbiting closest to Jupiter, at just further than the distance the Moon orbits our Earth (421000 vs 384000 km). It is a remarkable moon in many ways, but habitability is not one of them: it is the most geologically active object in the Solar System, but also the driest (least water to mass ratio). Its distinctive yellow tint comes from the sulphur compounds churned out by volcanoes and shot up to 500km from the surface. The volcanoes themselves are incredible peaks, like the Boösaule Montes reaching twice Mount Everest's height at 17km! Volcanic eruptions in low gravity are spectacular. This moon is a champion in another statistic: density. At 3528kg/m^3, it is the highest in the solar system, surpassed only by a few metallic asteroids. Io orbits Jupiter in a mere 42.5 hours, wobbling enough to cause tidal forces to lift the surface by as much as 100m. As it does this, it flies through the most intense parts of the gas giants magnetosphere and gets bathed by 3600 rem of radiation per day. This is 6 times the level that caused Chernobyl workers to die in months, every day. The safe limit is 360 times lower. This is 18000 times the yearly radiation we encounter on Earth, per day! In terms of temperature, the surface varies between sulphur ice fields at 143K (-130 C) and volcanic spots hot enough to melt steel at 1922K (1649 C). Io has an extremely thin atmosphere, composed mainly of the scorching remains of volcanic emissions. It glows in the day and collapses as snowfall when the moon passes behind Jupiter. Due to the ions being stripped away by Jupiter's magnetosphere, Io builds up an incredible charge across its surface, reaching 400 million Volts. Lighting strikes discharge a potential of 3 million Amperes on Jupiter's end. The plasma torus visualized In other words, Io is a fascinating place, with a great many potential uses, but it is worse for colonisation than even the sun-facing side of Mercury or the acidic hell of Venus. The rest is available here. Tell us what you think!

The design I calculated tried to go for zero relative velocity at the lower tip and 14km/s at the upper tip, leading to an extremely short window for rendezvous.... ...although I can see I design where a series of 2km/s wheels throw the payload to each other for a final velocity of 8km/s. Sorry, the retrograde is a mistake. Lunar return velocity is 12km/s in the prograde direction.

In the thread I linked, I did propose a spinning capture system, but the window between 0 and 100m/s relative velocity as the tether rotates away from tangent is as small as 6 milliseconds. A 100km radius tether improves this to about a tenth of a second, but either way, it is a very impractical solution. Airbags for the whole payload might be a solution. Instead of sitting on a station, there's a better use for them. Bring up 1kg of gas into orbit, then attach it to very efficient electric rocket to put it into an elliptic retrograde orbit, with the apoapsis at Lunar altitude and the periapsis at 200km. Encounter velocity at the periapsis can be as high as 12km/s. Have the gas slam into a heatshield to push a payload from a parabolic trajectory to orbital velocity. The 1kg of gas is worth 3.5kg of propellant in this scenario. If we use an inverted funnel instead of a heatshield, the gas will converge, compress and rebound with most of its velocity, becoming an effective 2450Isp rocket engine. A 10 ton payload starting at 0m/s and ending at 7.8km/s has a virtual rocket engine of 2450 to 856Isp. It would need 6.2 tons of gas to reach orbit, instead of 28 tons of rocket fuel.

3km/s sounds close to the specific velocity of a tapered tether. It is about 2.25km/s in an untapered section of Zylon. Could I ask a question related to the concept of braking a payload into orbit? More specifically, the part where the payload connects to the tether to start breaking. Here is a long discussion of the various designs I came up with to solve the problem of docking a 7.34km/s object to a 0m/s object: http://bbs.stardestroyer.net/viewtopic.php?f=5&t=166030. I settled on the concept of a hook being braked by a series of airbags, slowing down enough to be bolted through and form a connection between the main tether and a second tether from the payload. The continuous connection between the tethers allows the regular braking process to begin. Some images: The railgun was deemed as un-necessary, as the heatshield is lightweight enough to be pre-attached to the hook.

I understand now. A flywheel would move backwards at a rate equal to the momentum it imparted on the payload/spaceship. Thank you for the time you spent explaining this to me. Do you have any suggestions to make to improve the design?

I was under the impression that a flywheel can apply torque through friction which converts its rotation into linear motion of the tether.

Let's consider the system as two objects: the payload and tether system, and the flywheel. The payload is assumed to join its kinetic energy an momentum into the the tether+payload system instantaneously, without losses. In one example I worked out, the payload is 12.95 tons and the tether is 338.4 tons and the pulleys are 93.5 tons for a total of 448.85 tons. Payload momentum: 7334*12950 = 94.97MN.m Payload kinetic energy: 348GJ @7334 m/s After braking, using conservation of momentum: Tether+Payload momentum: 94.97MN.m @213.5m/s Tether+Payload kinetic energy: 10GJ (??) After braking, using conservation of energy: Tether+Payload kinetic energy: 348GJ @1245.24m/s Tether+Payload momentum: 558.9MN.m We'll use conservation of momentum. We have to handle the 338GJ deficit in the system. This is where the flywheel enters into play. A flywheel with -94.97MN.m of momentum and 338GJ of kinetic energy would be able to cancel the momentum and energy of the tether+payload system. The momentum will be angular, due to its rotation. According to half an hour of iterations on Wolfram Alpha (this equation), 10 flywheels of 10 tons each, with a diameter of 23.1cm and a rim velocity of 822m/s can provide exactly the required amount of angular momentum and kinetic energy to cancel those of the tether+payload system. After all is done, the momentum and kinetic energy of the tether+payload+flywheel system is zero. Nothing is 'taken' from the station to which all is this connected to.

If he has a command pod and a kerbal, then productivity cannot be 0. Therefore, it is a problem with his mod files.

This sorts of errors are usually the result of a not-up-to-date Extraplanetary Launchpads dll file. Contact the mod creator, @RealGecko

There are two versions of the Boosted Orbital Tether: simple and flywheel. The simple version is just a fancy weight on a string. Braking on the string slows down the station. To boost it back up, you use high Isp engines. A chemical rocket will have an Isp of 300-400, an electric engine can reach 10000 Isp. Therefore, recovering the lost kinetic energy using a few hundred kg of propellant is much more economical than using several dozen tons of rocket fuel. The second version builds up a kinetic energy reserve in a spinning set of flywheels. When the payload starts braking on the tether, the flywheel pulls in the opposite direction. This slows down both the flywheels and the spacecraft. When they both come to a stop, the station hasn't lost any kninetic energy or altitude: this method requires zero propellant, so it is 'free'. If you want an hour's reading on the details of this design, go here: http://bbs.stardestroyer.net/viewtopic.php?f=5&t=166030

You only need to cancel velocity along X and Y axis, so that the very high Z-axis velocity will hit you dead center. The 'boosted' part of the name comes from the initial rocket booster than pushes it up to 1000km altitude. 4500m/s is required, but that's only a mass ratio of 3.8. Getting to orbit requires roughly 9000m/s, or a mass ratio of 13.8. So for every ton the BOT puts into orbit, you save 10 tons compared to a full two-stage rocket. You can shoot out the last loop of wire to match the velocity of the incoming spacecraft and greatly extend the capture window.

A spaceship massing 10 tons and travelling at 8450m/s relative would have 84.5MN/m of momentum. My calculations give the flywheels a total angular momentum of about 1575MN.m according to http://calculator.tutorvista.com/angular-momentum-calculator.html The flywheels have more than enough momentum. Kinetic energy is used on a 1:1 basis, minus losses to braking, and they have a decent reserve for that too.

I first described it as a fishing line in space...

Hi! I've come up with four ideas for cheap access to space, involving orbital tethers. The first has already been thought up of: the orbital tether pulls a suborbital tether into orbit. However, my variant has the tether station itself being used as a platform which can change its orbit to increase or decrease rendezvous velocity. The second involves a tether being used as a 'runway': the tether trails behind a space station. A spacecraft latches onto the tether and starts braking. This speeds up the spacecraft and slows down the space station, effectively pulling the spacecraft from a suborbital trajectory into orbit. The third involves flywheels. The runway is attached to flywheels spinning in the opposite direction. When the spacecraft brakes, it pulls on the flywheels and slows them down, instead of slowing down the space station. The flywheels are kinetic energy reserves that allow for propellantless operation. The fourth involves replacing the tether with a series of pulleys. The relative velocity betweent he spacecraft and the tether can be very high in a simple runway, making braking hard. With the pulleys, the tether 'expands' like a bungee cord. The relative speed between spacecraft and tether is divided by the number of pulleys for easy braking. These ideas and designs are described and illustrated with calculated examples here: Boosted Orbital Tether Orbital Runway upgrades

Since in SimpleConstruction RocketParts are printed in the Science lab, maybe scientists can help speed it up? What do you think, @RealGecko

This is KSP. Of course I didn't.

I go the links to work thanks to @James Kerman

Thanks, I'll do this.

Hi. There 'i' icon on the top left of the editing bar is gone. The [imgur] tags do not work. Has the option to ember imgur albums been removed?

Hi! Here, I will post mission albums of very large rockets going to space to do Big Things. Planets are x4, distances are x7. First up, Bacchus station. 1950 tons while empty, requires a 46000 ton launcher to push it to space. Bonus flights: the Hermes spaceplane to recover the pilot, the Ore Delivery vehicle that fills up Bacchus station with 144 tons at a time. Imgur Album Have fun! More to come. Modlist on demand.

Good luck, the mod is in safe hands!

Go here:

This mod will be maintained and updated by @RealGecko. A new thread will soon appear for this mod, with links in the OP. He has impressed me with his skills and considering my relative inactivity, I think he is the right man for the job. Special thanks for his efforts!

I'll be more precise: if I have Vessel 1 with tanks A and B, sitting next to Vessel 2, I cannot move resources between tanks A and B.