Rakaydos

The solar orbit demo is a milestone we'll have to pass if we want to go almost anywhere beyond LEO. There's other places in earth's SoI we can go, but they'd have an even higher Dv requirement than a slingshot. As for science, it's a tech demo. Internal monitoring, position and direction detection, everything we need to make it fly gives real information back to better funded groups who want to follow.

Let us posit a device, that can be affordably manufactured in space, that turns Co2 into a graphne baloon filled with o2, and leftover carbon, using solar energy. Let us suspend this device over venus on a baloon. Let it make more baloons, and put more devices under them. (the Leftover carbon gets compressed into graphite and dropped to the hellish surface) Eventually, all the C02 of the atmosphere will be locked into graphite blocks and oxygen baloons. How much would this reduce the atmosphereic pressure of Venus? Can we improve this number by using the leftover carbon to lock nitrogen atoms in solids as well? What useful compounds can we turn Sulpheric Acid into?

A person (and basic life support) may be cheaper to supply than electronics of sufficent complexity and rad-hardening.Think suicide bombers in tin cans, swarming down expensive drone fighters.

The GTO to Solar Orbit tech demo is the only croudfundable possibility for that, I think. Limited scientific payload, simply a proof that such a mission is possible on a budget, and other better funded missions will follow with better equipment.

They have a flight time of a few centuries. A little prograde/retrograde will put Jupiter wherever in it's orbit they want. A little more, and they can plan multiple planet alignments. It's not like they wont know about gas giants in their destination system before they leave- we know as much already for plenty of exoplanet systems, and we cant even see them yet, just extrapolated their existance.

Hmm... you generally talk about gravity slingshots as something to get you out into interstellar space, but what if the alien probe timed it's arrival to slingshot jupiter to "capture" into Sol system, like you might use Laythe to capture into Jool orbit? Since an interstellar slowboat probe has nothing but time, it then procedes to get on the Interplanetary Transport network and slingshots everywhere, beaming close up images and radio data back to the home system.

Life is Entropy by convoluted means. The sun radiates on the earth, and eventually heat is lost by the earth into space. but somewhere between there, that energy pumps a waterwheel of nigh-infinite complexity, full of feedback loops like eddies in the current. The cycle of life, of water, of carbon, O2, and so on and so forth. If the sun vanished, there would still be residual energy in the system, but once the "batteries run dry", so to speak, it's all over.

thats pretty much the premice of the show Eureka... a small town filled with the best and brightest with unlimited funding. And the main character is the only one in 50 miles with common sense.

I agree, but as I mentioned earlier, it would be less for saving Dv, and more a method of landing on a small airless body with a TWR too low even for said small airless body. an Ion powered phobos "lander" that touches down at less than 7.5 m/s, despite not having the thrust to land normally.

I was looking at an approach similar to this for "lithobreaking" a Phobos cubesat- with an orbital velocity less than 7.5 meters per second (at the height of the highest mountians of phobos) it's less a matter of D/v, and more a question of landing with a TWR of less than 1. Smoothness is even more an issue than the moon, though.

if you + the suit weigh less than the atmosphere displaced by the suit, you'd float. if the two numbers are close enough, sure, you can swim.

I believe Airship to Orbit (Perhaps supplimented with something like an external microwave powersource and a thermal rocket) has most of the advntages of a space elevator, and less (or at least, different) drawbacks.

If we are to ever live with our feet on another world, manned space exploration is essential research on lifesupport, sustainable enviroments, recycling, and more critical infrastructure. Losing our manned presence in space would do the same thing that canceling apollo did to our interplanetary capablity. A sustainable colony- whether it be Mars, the Moon, Europa, or the clouds of Venus or Saturn- would be a major step for the human race, a chance to survive a truly global catastrophe. A manned presence on an Exoplanet would be the next stage, the ability of humanity to survive the death of the Sun- the first full step of an eternal human race.

There's been a lot of talk since the poll was put up... the short version is that any mission beyond earth's SoI will be a stretch goal, and the biggest point of failure is setting up the "Arianne 5 slingshot." Being able to acomplish a solar orbit to earth return proves that it is possible to reach just about any target you could care to name in the solar system, so if we get that (very expensive) stretch goal, that will be the primary mission. Aerocapture or slingshot would be secondary, at least on the first mission. Really, practicing aerocapture at Earth is kinda a best case situation- we dont need to put the atmospheric sensors on the probe because we have other sensors in orbit already, and we can apply near-real time Command and control.

Did a bit of refinement in Wolfram Alpha for a Phobos Lithobreak. At an altitude of 13 km from mass center (so just a few hundred meters below phobos's highest mountian) orbital velocity is just under 7.5 m/s, and that will be barely a glancing hit. If we can build the cube sat such that, say, the solar cells dont snap off when we bounce and sled, Lithobreakining seems a resonable alternative to a high IsP engine.

Burning a nitrogen/oxygen bond with a fuel generates more ISP than an oxygen/oxyge bond, because it allows two nitrogen atoms to bond into N2, a reaction that by itself generates quite a bit of power.

Can you post a link to the required mod?

There is also a minority of us looking into a technology demonstrator for a cubesat based mission beyond earth's sphere of influence. Using a Geosynch Transfer Orbit ride and burning under our own power to a Lunar Transfer Orbit to slingshot out of the earth/moon system. Idealy, we would like to target a solar orbit with a 1 AU semimajor axis, which would be nessisary for a timely earth-slingshot, which would be considered a total succeed in our primary mission. This slingshot capability would demonstrate the capability to (hopefully affordably) send cubesat-based hardware to Venesian or Martian sphere's of influence, without requiring independant launch hardware. (it being a cubesat piggyback on a commercial geosynchonus orbit launch) Currently, we (the minority interested in this advanced project) are looking at a 3U with at least 600 m/s of delta V and sufficient guidance capability to make the required burn, and a basic heatshield to practice aerocapture with (either after a 1-year orbit, or at a more distant destination). Any mass we can reserve for advanced projects, we may be able to sublet to other interested parties. (The "Phobos mission" group is an interested party here on the forums, but the D/v + TWR requirements are a bit steep for what we can fit in a 3U, and requires everything else to go perfectly first- so certainly not something to go on the first mission.)

Check my math here. Assuming everything else goes to plan. We get a GTO launch, we lunar slingshot into the correct orbit, the computer survives a year in solar orbit, we get the mars intercept off the earth slingshot, we aerocapture at mars, and nail the phobos transfer orbit. Can we land? Phobos has a surface gravity of 5.7 milimeters per second per second, according to the nasa page. Fully fueled, our cubesat will weigh no more than 4 Kg- less, after burning to Lunar transfer Orbit and making course corrections. To have a TWR of 1.0 when wet (and thus >1 when it reaches phobos), by my math we will need 22.8 milineutons of thrust. According to the Ion drive wiki page, that is well within the capability of an ion drive... if we can give it something on the order of a Kilowatt of power. The largest expanding solar panel listed by Clyde Space for the 3u is only 29.2 watts. 3 kilos of Lithium Ion may be able to power the ion engine for as long as the battery lasts, but needs a cell to recharge the battery, and severly pinches the remaining mass for the cubesat. Alternatively... if I recall my Heinlen, Phobos is said to have an orbital velocity reachable by a running human. The world record fastest runner, Usain Bolt, has demonstrated a peak speed of 12.42 meters per second, according to wikipedia. Taking this as a worst case orbital velocity, can we design a probe that can lithobreak with that kind of horizontal velocity? Worst case, a 45 degree impact into a mountian side against the heat shield. Anyone want to refine the orbital velocity? or have any comments about either approach?

Speaking of the electrical system, what are the best low mass/high energy solar cells I sould be looking at?

Did they finally do anything for the Mk 55?

Not too leisurly, though, unless we rad harden the buffer as well.

The UT69RH051 seems like the best chip for the Solar Orbit mission, and is our first hard price tag we can put on our "advanced mission." We still need to price the ion drive and the power source- almost everything else, we can manage in the software or cobble together from spare parts.

For the rad hard version, do you think that would be viable for a 1 year or 3 year mission, going solo? or would the solar orbit maneuver and phobos missions need to pack redundant systems?

I'm still working on the Phobos mission, in another topic, but my main limiting factor is hard data. Even so, it's looking like Phobos wont be the first mission, even with *ALL THE FUNDING*. The first thing needed is to perfect the GTO->Lunar->Solar-> Earth maneuver chain, while demonstrating at least a year's endurance without the computer going bonkers from space radiation, and practice the mars aerocapture here at earth where we have better command and control. Once that's down and we can relaiably acchieve it, then we can use all that, then use earth to reach for mars, aerocapture and aerobreak down to phobos, and attempt a landing. It's not a science mission, it's an engineering challange- to boldly go, so to speak.