NiteOwl, thanks for the balanced commentary. I wish fervently that human exploration of space were possible and feasible. But we are not there yet and until we fix the radiation and life-support issues, not to mention the need for an FTL drive, it's not going to happen.
terminal descent velocity would depend on the object cross-section and the atmospheric density profile. who knows? Titan atmosphere could be pretty thick. I'd be worried about going splat into a mucky surface and becoming stuck in a crater filling up with liquids. But that's the risk you take. Send a few different sizes and hope you get a few good landing spots. The Huygens probe hit the jackpot with that awesome sidelong view. It looked like a long stony beach down there.
Just like those military observation drones, the use of robotic things for exploration in areas where life support would take a whole lot of effort is a better choice. If the robot carrying space craft has a misfortune we would be unhappy, but nobody would die. So there is at the very start an excellent reason to use robots. On top of that, there is much less reason to be concerned about bringing them home, except that we do want to recover those soil samples.
But I am really wondering about the afequacy of this hardware technology in two areas. That 15M/sec is only about 30MPH, and I think that probably the fall from space will produce a much higher entry speed, so the landing impact may still damage the payload. My other question is about the quite small contact area being able to support the ball high enough to roll, if the surface is dust and not strong enough to support the load. Does anybody really know if the surface can support what will be a fairly high ground pressure?
So there are some questions, although it certainly is an interesting concept.
I agree, NightOwl. A manned mission to Titan is well beyond the technology of today. It was not my intent to lament the lack of impetus to achieve that lofty goal. Ann further clarified her post. I was more speaking to the lack of an 'all of the above' strategy in space (manned vs unmanned, why not both?). We sort of had that better strategy back around the VSE days (when Griffin was running NASA) a decade ago but faltered into sticker shock and quibbles about the details. 'what do you mean space is expensive?' 'Moon/Mars' etc....
I love the new probe ideas and this kind of design thinking ought to be encouraged. Keep the posts coming on these things, Ann.
RogueMoon I didn't condemn anything. What I said was, I don't think that human exploration is likely to succeed, for multiple reasons in addition to technology, but I do think that robotic exploration is likely to succeed. The risks are huge: how long humans can live in space since we have to take tons of stuff we need with us to make sure we as biological systems survive, the high costs of fuel (I consider that one of the risks), how to protect us from radiation (a huge problem), and the extremely slow speeds our tech can now travel at. There are others as well. If it were that easy, low-risk or economical we'd have sent people to Mars, instead of robotic rovers. I think it's sad that we aren't doing more human exploration and (I think) aren't likely to. But personally, I'd prefer not to get excited about something I think has a low probability of happening.
First, great article Ann and I agree 100%. It would be great to send a manned mission, but we're not quite there yet. Robotic missions, at least at first, should be able to tell us a great deal about what's out there.
Titan is too far away for manned missions. The planned manned mission to Mars will likely be a one-way trip for the people going along. We spent an average of $1.5 billion per launch for our space shuttle program. That was just going into orbit. The cost of a round-trip ticket to Mars will likely be much higher. Titan is much farther away than Mars. 1.272 billion km compared to 54 million km (at closest approach). Even if we could go fast enough to make such a trip feasible, we don't have anything to protect the hull of our spacecraft at that speed. A marble floating in space would punch a hole right through the hull at that kind of velocity. Until we come up with a deflector array or navigational shields or enhanced hull plating we're stuck cruising the neighborhood. Maybe something good will come out of Area 51.;)
Chuck, glad there's another one of us out there :) Regarding visuals, the first time I saw an actual photo of Mars' reddish soil, it was almost a religious experience. I had been reading about the red planet since I was 7. And by golly, it really IS red looking.
Ann, it's a neat idea to use a bouncing ball to roll over the seemingly wet unpredictable surface of Titan. (Aerostat exploration of Venus from the skies is another great idea.) But how can you support an untried, technically challenging endeavor such as this, but condemn the manned spaceflight program on a technical basis?
Two-man teams have explored the surface of the moon on six different occassions over 40 years ago. A manned mission would be a lot less risk as there has already been precedent set by the generations before us. Cost maybe, but risk? No.
You do have a point that manned exploration does bring up the excitement of old times. "Catchy" implies lots of people can get excited about it. Excitement justifies research and exploration ventures. So why is the USA doing something less than "catchy" or anything that does not have as much pyschological momentum behind it?
It's too bad in these times we don't even seek to repeat the feats of generations past. It comes down to whether people want to justify a growing space program or just pay another team to have it done by robotic proxy. For my tax dollars, it's a poor return on investment. It does matter to many if it's manned or not. One is a greater mark of progress than the other. Think of the knowledge gained if we only quit settling for less.
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