I'm confused by your bicycle analogy, but I think you're saying that a single manned mission can bring home as much weight of samples as hundreds of unmanned missions.

The reason that the Apollo missions were able to return such a heavy load of samples is because the spacecraft were enormous, not because there were people on board. You seem to think that, because unmanned spacecraft can be small, and in fact are usually small, they have to be small.

Would you care to explain why you think this is so? Why couldn't you build un unmanned spacecraft that's as large as any manned one? In practice, unmanned spacecraft are small because the budget for unmanned missions is usually modest, and they don't need to allocate a lot of weight for life support systems, food, etc. However, if you were assigned a launch vehicle and given the choice of flying a manned or unmanned mission, I can't see any reason why the latter would have to use a smaller spacecraft.

Exactly why is my argument about weight budgets incorrect? Is it not true that human beings, their life supports systems, food, etc. amount to a lot of weight? Is it not true that the need to return this weight to Earth necessarily reduces the weight allowance that you can allocate to sample return for a given total spacecraft mass? Does the presence of humans on a spacecraft improve the efficiency of its engines? If I'm missing something, I'd like to know what it is.

Also, have you been keeping up with the Mars rover mission? I'll admit that the rovers are not fast, but they are capable of covering a rather wide area, taking panoramic photographs (to put rocks in a proper context), taking close up photographs (to study rocks in detail), and performing spectroscopic and other measurements (to get information on the chemical composition of rocks).

A similar, but more advanced robot would be ideal for a sample return mission. A moderately large "mother ship" could land somewhere on Mars, with two or more rovers aboard. The rovers would be larger versions of spirit and opportunity, but with robotic arms and scoops for collecting samples, and a mechanism for putting samples into separate boxes. The boxes could easily contain a serial number, and the rover could record which sample went into which box. The rovers could wander around, identify interesting rocks (the decisions being made by people on Earth), pick them up, box them, and load them into the mother ship.

When the mother ship was full, it would take off, dock with a spacecraft in Mars orbit, and transfer the sample container. The second spacecraft would then return the samples to Earth. It would also be possible for the lander to return directly to Earth, but this would require it to take enough fuel for the return journey to the surface of Mars and back, which would be inefficient.

I can't see why such an unmanned mission would not be possible, although it would be challenging (and interesting). It would be able to return a large mass of samples from an area within a few kilometers of the landing sight, with detailed information about where each sample came from. For the same sized launch vehicle, it should be able to return a larger mass of samples to Earth than a manned mission. With a smaller launch vehicle, it could return the same amount of samples as a manned mission.

The same weight budget argument holds true for data return as well. The simple fact is that every kilogram of weight that a manned mission allocates to the astronauts, their food, or life support, is a kilogram that an unmanned mission could use for better communications systems (to transmit more data), more or better instruments, or more electrical power. The life support systems also use a lot of power that could be used for data transmission or instruments.

I've now explained in some detail in my various posts why I think an unmanned mission can return a greater weight of samples or a greater volume of data than a manned one. Please explain why you think I'm wrong. Please do not confuse the issue by assuming a largr spacecraft for the manned mission.

What exactly have Cassini, Mars Pathfinder, Mars Global Surveyor, Magellan, Spirit, Opportunity, and dozens of other probes been doing? What do they use to collect their data?

Exactly why is data from unmanned spacecraft taken "in isolation"? To take Mars as an example, orbiting spacecraft have been returning photographs of almost the entire surface at various resolutions, laser altimetry data, spectroscopic data, and data from many other instruments. Spirit and Opportunity have been taking broad, sweeping panoramic views of their surrounding, as well as studying interesting features from close range, using a suite of different instruments. They can even grind away the surface of rocks to study the inside.

All this data can be combined by scientists on Earth to build up a picture of the Martian environment. Exactly why does this not constitute putting the data in context?

Thanks for that. It looks like a good read, and I've bookmarked it.

Let me end on a note of agreement. I can see that you're a big fan of the Apollo project, and for what it's worth I also think it was great. I think cancelling the final missions was a big mistake, and would have liked to see NASA keep sending men to the Moon rather than into low Earth orbit. I agree that Apollo achieved a lot scientifically, and would have achieved a lot more had the final missions been flown.

The Apollo spacecraft had to be enormous because there were people on board. Being enormous, it was trivial to return hundreds of kg of lunar sample materials.

Dropping an equal tonnage of robotic probes on the moon wouldn't have returned anywhere near the science--robotics at the time were extremely primitive, and speed of light lag even over the short distances to the moon made navigating the robots extremely difficult. The robots could make up for a bit of this by their longer stay time, but that wouldn't have helped too much--they're limited by the number of day/night cycles they could endure.
You could, but if you did that you may as well send people and get the advantage of having people on site.
The presence of people increases dramatically the effectiveness of the exploration and science able to be done. Despite their disadvantages, people are more effective. You are overestimating by a large amount the capabilities and effectiveness of robotic exploration.
They are unable to clamber out of small craters, they are unable to do anything they weren't designed to do (like, check what's under that rock, see what's under the current dust layer, check if the ground feels spongy, improvise an experiment, whatever).

The future of human (and not "manned") space flight belongs to space tourism, since, agreeing with that Wrong Stuff report, there's little scientific reason to send people to space with current costs. Only when thousands or millions of people go sub-orb, orbital or lunar merely for the sake of it will space travel be affordable. With this new X-prize spacecraft, we may have a space tourism industry within two decades.

I am not sure I want to do this, but might I offer a similar answer to Arthur Clarke's cited one earlier?

Crewed or non-crewed missions can do some things robots can't do.

Robots can do things we can't do. Like hang around on the surface of Venus and get melted. (Most people wouldn't want that one).

I think if offered, many people would want to go to space, but they aren't necessarily the people you would want to go. Important missions do not need adventurers, and there is a reason the training is so rigorous. I cannot imagine myself reacting in the right way to an emergency aboard the shuttle or a long-haul spacecraft, however much I want to go. (And I think if you told people they had a 90% chance of dying setting up the colony only a very few would take that -- and they wouldn't be the ones you wanted on the mission, either).

The economic argument has more validity -- at least long-term. But there are some things to think about -- first, colonization on Earth, to places that required little equipment to be in, never bled off much of the home country's populations. The only exception might be Ireland, and they had some very special circumstances there. This with millions coming to the US alone from various European nations early in this century, to say nothing of all those Italians and Germans who went to Chile and Argentina.

So Earth being crowded won't drive it, methinks.

Resources? Not sure about that either. Some it might work for, some not. Some very important metals -- tantalum, for instance -- may not be abundant enough in space to make any difference to our very serious supply problem here.

The best argument for space colonization is the long-term survival of the species -- after all, the sun will eventually go nova. So sometime in the next 5 billion years or so we should make plans to leave. To say nothing of that occasional asteroid. We are in a situation right now where a major environmental stress could cause massive disruption to our civilization. Space colonization is a hedge against that.

How to do it is the other issue. That can be debated, but you have to start someplace. I would suggest sending a relatively large group to a place like Mars initially -- some back of the envelope calculations tell me that while the initial cost per person is very high, it goes down the more people you have on the ship. (Kind of like renting an apartment in New York -- for one person alone it starts at $1,100 a month on average, but a two-bedroom runs about $1,900 or so and a three-bed goes for $2,600, and so on). Big and expensive? You bet. But the return might be better.

Some of it tho, has to do with deciding what is important. As a society we make these decisions all the time and they are never really all that logical. (I mean, please, we plan to spend $600 million in my city on a football stadium? I like sports too, but I am not for making professional teams taxpayer-supported, unles the profits are giong back to the taxpayers, which is only true in Green Bay).

So maybe that's the issue. Figure out what is important. And make policy decisions that reflect that.

Call me crazy, call me stupid. But that's what it looks like to me.

Can you imagine Casinni as a manned mission? It is a "huge" craft weighing a few tons, but that's nothing compared to a manned mission. It took 7 years to get there, and will explore for at least 4. And there is no way to get back.

For missions like the one on Mars, we might complain that the rover can't pick things up and look under rocks, break pieces off and examine and feel, and otherwise manipulate the environment the way a person can, even a person in a space suit.

Well, why not? Building a robot that can manipulate things that well is possible with today's technology. Shipping an existing robot would require a "space suit" and precautions against the harsh environment; but so would sending a human! I conclude that more dexterous robots can be made robust enough to handle a Mars mission for less than the effort of making a protection system for a person.

The robots sent to Mars are really stupid and primitive even by current standards. The pathfinder rover in 1997 was reported as being able to perform a hundred thousand instructions per second! My desktop PC was doing a respectable fraction of a billion at that time. And the rover could only hold one photo at a time; while my first digital camera held dozens on a chip and at several times the resolution.

I assume the issues are that of fragility and the rough environment. Investing what it takes to package/protect more modern computers would be a fraction of what it takes to protect a human.

So I see a false delemma. It's not stupid clumsy robots vs. humans. It's a continuum of capability, with humans at the very top. If the robot isn't good enough, it does not mean that we must send a person instead. Send a better robot.

A rover could have general purpose limbs with graspers and weild a geologits hammer, take a sample, and hold it up to its "eye". And the team of geologists plugged into the data doesn't have to worry about staying alive or even the rigors of fieldwork, and they can be hired and replaced and take vacations, etc.

In a few decades computers will be powerful enough to have general intellegence. Then you can simply tell the robot to "go over there and take samples", rather than micro-manipulate its every move. Its general-purpose hands can replace its own gaskets and splice its own wires, keeping itself going and adapting to the situation both in real-time under its own control, and under careful direction from the controllers on Earth.

I don't think a person on Mars will be "doing geology". He'll be gathering raw data and making measurements. The analysis will take months at least, and be done by specialists on each type of rock. The geologist wants the data; he'll have his grad students get the rocks.

—John

I think the chief advantage of a human over a rover is the ability to make quick judgements and then act upon them, without the long delay times it takes to figure out what the rover should do next. A human with Apollo-caliber surface equipment could have done everything that either rover has done so far in a day and would be ready to do the same again tomorrow.

This does not invalidate your remaining points, however.

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Everything I need to know I learned through Googling.

Maybe, but trying to smell or hear any extra terrestrial planet would probably kill you.

Moose: If you brought me a dead cat, would it not have evidence of what killed it on its body? Could I not take it to a vet and have him tell me what it was that killed the cat?

Isn't that an analogy for how almost all work in the field of astronomy is done?

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"Most editorials are written by people that love to argue but got kicked off debate team for not making any sense." -Seanbaby

At least with a manned mission, we'd know what color the darn sky is at least.

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You're a coward and a liar and a thOOF - Bart Sibrel

The first thing I thought of when I saw this topic was that Robert Park said something similar in his book Voodoo Science (and Steven Weinberg mentions him in the article). I bought the Guardian today and found this in the Life section: Space is not our place, Robert L Park, Thursday July 8, 2004.

While I've been amazed at the long distance repairs of unmanned spacecraft, there is only so much that's possible. eg the lifetime of Spirit and Opportunity on Mars is limited because the dust can't be cleaned off the solar panels? Now if there were an astronaut with a duster...

Having read the accounts written by people who have been into space, there is nothing like really being there (not even a holodeck). But as long as they go willingly and know the risks.

BTW has anyone decided what colour the sky is on Mars?

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Carolyn

"All the screens are filled with heroes and losers, but the sky's still filled with stars"
...Midnight Oil - 'Golden Age'

We're all talking about robot vs. human "missions". Well why missions? Let's admit it: the only reason for people to go to space is because it's cool. The only thing we can do that robots can't is enjoy the thrill of discovery, experimenting. All this "science that humans can do" stuff is just something to justify budgets to congress.

The cost of one manned mission to Mars (at least $180 billion, probably by 300 billion or more) could send hundreds if not thousands of all sorts of robots and probes.

I'm against "manned missions", because that flopped concept draws resources and attention from true human space travel. If the $10 million X-Ansari Prize has produced stuff like the $20 million SS1, imagine what a $10 billion prize could do for Moon/Mars stuff.

And in between the private competition would offer sub-orbit and later orbit to the general public for a few thousand dollars (orbital tourism would always be 10 times the price at least, and would of course happen later, maybe by 2025-2030)

And this market would create technology at affordable prices to place people in orbit and beyond.

On the other hand, if we stick to that "Manned Mission" stuff to do pretend-science, we would drain gazillions of dollars from the world's budget, generate little profit, and then land a couple of public office holders on Mars by 2039 (if they don't die or kill themselves in the 3-year-journey)and then take two hundred years to return.

What people don't realize is that the Space Agency concept was invented in the USSR and then copied by the USA in the Apollo rush. Nasa is therefore as efficient as the Soviet Union, so are the other space agencies. Look at the Shuttle, which was supposed to fly since 1978 at least 45 times a year at less then $90 million a launch, but never flew more then five times a year, costs $500 million a launch, exploded twice and never built the Freedom space station (now it needs the Soyuz, the space-Lada, to build the ISS, which is also a near-useless money-pit). Not to mention the now proposed "Crew Exploration Vehicle" (it's suppose to explore its crew?), a return to the expendable Apollo-Soyuz-Shenzhou concept!!! hahahahahaha and at $40 billion to develop (don't forget it'll actually cost much more)

Nasa actually has been thwarting private efforts to render orbit affordable, as it did with that helicopter-rocket and others, and throwing money at the Boeing/Lockheed Martin mafia (not to mention the Russians!).

Picture what would have happened to computers if they had been restricted to the Government-Corporation combo – as a matter of fact, to all technology.

Therefore my conclusion is: let the agencies do the probe-robot stuff. Let capitalism bring the thrill of space travel to people, initially through offering of prizes. Nasa could easily cash out several billion if it grounded the Killer Whale (doesn’t the Shuttle look like one, besides killing people???) and the International Money Pit. Of course legislation has to change (Nasa can only offer some $100 million in prizes, I guess), but that’s minor.