Ending the Space Shuttle program will also mean the loss of a lot of jobs. Strangely enough I do not read much about protests against this.

I agree that all those jobs are very important for the people involved. But if you want to keep those jobs you are surely not going to fight for continuation of a program that costs much more than those jobs and in the end will not really get America on the next level. Why not do your utmost best trying to get those people involved in the new Space program and spend money on helping the remaining people to get a new job and some transition support money?
Is governor Crist really trying to help both the Florida people and America or is he just thinking about his own future in politics?

“socialism doesn’t work” according to Mo Brooks. Well, extreme socialism surely does’t, I agree. But extreme capitalism doesn’t work either, as the financial crisis all to clearly shows. It is becoming more and more clear that neither extreme is the answer. If that were the case then Russia or America would have been a paradise to live in by now and they are neither. Both systems have created a lot of problems as well. Maybe it simply isn’t that black and white as some out there want us to believe.

The refueling depots have the potential to change the whole way we think of spaceflight. I can imagine infrared vision is what the DoD is looking for too. Such advanced observation capability is no more the weaponization of space than current earth observation by millsats. Not as exciting though as the astronomy/NEO capabilities.

There are a number of spacecraft already that have been spontaneously retargeted to new flyby missions after their main mission was done. For example, the International Sun Earth Explorer was launched along earth’s heliocentric orbit to a halo orbit around an Earth-Sun LaGrange point. Once its main mission was done, an opportunity to flyby the comet Giacobini-Zinner was discovered that crossed earth’s orbit at low inclination. ISEE was redubbed ICE (International Cometary Explorer) and became the first spacecraft to fly by a comet. More recently the Stardust spacecraft, after having sent back the first sample to earth from beyond the moon (comet dust), was retargeted to fly by comet Tempel 1. This flyby will be exciting because it will be the first look at it since Deep Space 1 smacked it with a big copper warhead. Stardust will be able to look at the crater without the big debris cloud in the way. The ability to spontaneously retarget spacecraft is severely restricted by the propellant on board, but nevertheless has been done to great effect.

The telescope network I propose would simply have such spontaneous retargeting as its main mission, restricted only by the ability of a spacecraft to return to its refueling supply chain, which isn’t much of a restriction in this application. If the satellite equipment has long half-lives, the spacecraft could stay in service for on average two to three decades and get close-ups of over a hundred earth-crossing comets and asteroids as well as closer-than-earth telescopy of the higher-inclination earth-crossers and much other valuable astronomy. We could also repeat the Deep Impact experiment and excavate fresh craters on many of these objects, discovering what underlies their often misleading surfaces.

I would be interested in such a concept – protecting our planet is even more important than getting to a another one. How would the propulsion mechanism affect the instruments if so?

If it saves time and money it would certainly be a blessing for NASA. Multiple telescopes would enhance the resolution significantly I can imagine. Reminds a little of TPF.

Now, whenever anything we can see several months ahead of time crosses earth’s orbit at low inclination: NEAs, comets, etc., we can intercept it by advancing or lagging one of the spacecraft along the orbit. Indeed, most objects cross twice and we can intercept it twice with two different spacecraft. For very low inclination objects the spacecraft itself can do the small plane change to make a very close flyby, otherwise it’s not as close as a typical flyby but we still get much closer than earth itself.

When the spacecraft aren’t taking flyby pictures (the vast majority of the time) they do normal astronomy. They can look at the part of the sky that from earth is in daylight that time of year, watching for events we otherwise would miss.

If there are enough earth-crossing objects of interest that cannot be predicted well ahead of time (e.g. new comets), or if we want the flexibility to decide targeting priorities after launch, it pays to launch a minimum amount of propellant (cryogenic xenon or argon) with the spacecraft and then launch more propellant to refuel them as needed.

Even more objects cross Mars’ orbit around the sun, and that orbit also makes a great place to observe the main belt asteroids and watch for events there (asteroid collisions, outgassing events, and so on), but the supply line is longer so the benefit from refueling is less than the shorter supply line to spots along earth’s orbit.

Bravo! I’m in total agreement. The ideas for refueling Dawn spacecraft would be enormously beneficial for finding the right place for ISRU equipment to land.

I would just say that the human element to all this will naturally evolve along with the robotic technology as long as NASA continues to support the “seedlings” in the commercial space industry. We should continue ISS indefinitely to support continuing research so that we can, at least, provide a pathway for eventual HSF to evolve, whether it be commercial, or NASA.

I hope DoD is listening. Send your remarks to the President and science/tech committees in both Houses. And send them to Defense Link. But also check out Oler’s suggestions, which are fairly closely aligned with yours and mine.

In the new Obama budget depot technology is funded directly. No indirect motivation or hypothetical market needed. We should take advantage of it to get as much tech demonstrated on-orbit as possible before the political winds change again.

There’s also great potential for the funding to be motivated by national security, or even paid for by DoD, if the architecture suits their needs for maneuverability to avoid threats, ability to change orbits, and greater lifetimes. There’s also probably a commercial market to extend satellite lifetimes once the technology becomes mature. The benefit comes about because “the biscuits and syrup are never even” — satellites either run out of propellant, in which case they could extend their lifetimes by refueling, or they die with propellant still on board, in which case they wasted money launching propellant that was never used. Depots and refueling could both reduce launch mass required and extend average lifetimes.

Look for applications where flexibility is key, or think of how to tweak applications so that they gain from flexibility. For example, imagine if the Dawn mission to the asteroid belt were refuelable and designed to run for (on average) thirty years. Keep sending it new tanks full of argon once every five years until it dies. That way it can keep going to and past its lifetime, but however long it lives the amount of propellant it wastes when it dies is minimal. It could go into orbit around dozens of asteroids before it dies. Something similar could be done with a mission to visit several Jupiter-family comets, or to keep a Jupiter orbiter operating for a very long time. There are some obvious and not-so-obvious analogs to this in military operations. Refueling provides a flexible path, as they say, for a given mission. In businessman’s terms, refueling gives you real options, the financial value of which can often be calculated using the formula for financial options.

None of this requires astronauts and indeed people tagging along would greatly weigh down the operations, figuratively and literally, as discussed above. As for how astronauts might in the long run take advantage of the technology, your ideas are interesting, but I think specifics are premature. But here’s a general approach to think about: an on-orbit flexible mission. An Orion or similar sits outside the ISS which is staffed by ISS astronauts who do their normal work up there but are also trained to do exploration. outside. When something interesting happens — for example, a big meteor hits an asteroid, comet, or moon, digging a big crater that exposes what is underneath, which is very scientifically interesting, since we normally only get to see surfaces, which may be misleading — propellant is quickly sent up from earth and the astronauts are ready for the next orbital window to visit the object. Or, closer to home, you send up propellant to visit GEO only when something gets broken up there that they can fix — they stay at ISS until that happens and we need to wait only for the propellant. Hah, that should really stick in the craws of some space activists, we even launch the astronauts before we choose a specific goal.