The feature where we pester smart people. This week's question revolves around near future spaceflight, should it be manned or unmanned?

In case you've missed them Jose's original piece is here and Charlie's is here.

In terms of immediate priorities, there's no question that unmanned missions are far more cost-effective. At the moment Cassini is showing us yet again that every planet, moon and lump of rock in the Solar System is not only unique but has surprising features. The Mars robot explorers have shown us the same. But they've also raised questions that would be very easy to answer if only we had people there. In the longer term, we have to go ourselves.

Ken MacLeod is part of a new generation of British science fiction writers, who specialise in hard science fiction and space opera.

Ask an antarctic researcher if he/she could be cost effectively replaced by a robot without any loss of understanding of his findings. It is the cost of space transprtation which drives this sterile debate and it is that problemwe need to solve. Robots should always remain our assistants, not our substitutes.

Alan Bond is Managing Director of Reaction Engines Ltd [1] and associated with Project Daedalus, Blue Streak missile, HOTOL and Skylon.

Well, I agree with Carlos. Spaceflight isn't just about economics; indeed, I decry the worldview that says that all things should be reduced to the bottom line. Space travel is an ennobling adventure; it's part of our reason for being as a species. As the closing title card of Star Trek: The Motion Picture said, "The Human Adventure is Just Beginning."In fact, I sum up a lot of my thoughts on this in my own novel Hybrids, which contains this speech on this topic from a fictitious US president.

Robert J Sawyer is a rockin Canadian hard SF writer

Jose, being an astronomer by training, I'm prejudiced in favor of unmanned exploration -- the scientific return per dollar is orders of magnitude greater than you can expect from manned spaceflight.

Add to that the near certainty that George Bush's "return to the moon" pledge is just so much vapor. There's no money. There wouldn't be enough money even if he rescinded the tax cuts his wealthy pals enjoy.

Add to _that_ the fact that the shuttle has always been a dangerous juryrigged compromise vehicle, and now it's a geriatric one. Incredibly, there's no real successor on line; it will be at least eight years before one leaves a launch pad.

I'm greatly in favor of eventual manned flight, and I do believe that the ultimate destination of humanity is space. But the next step is a technology that will allow the transfer of large masses to Low Earth Orbit economically -- perhaps the space elevator; perhaps something else -- because nothing permanent is going to happen until cislunar space offers goods and services that can't be had more cheaply on Earth.

I'd like to be proven wrong.

Joe Haldeman has been shot on three different occasions. We don't know why, he seems nice enough to us.

Dear Jose: You and Charles are rehashing an argument I've watched develop over many decades.

In the 60s I couldn't figure out why they didn't land on the Moon with Apollo 1. Why wait until 11? Okay, that was naive. The machines have to be developed and tested, and the men don't get there without the machiness. What I notice is that your arguments (for the machines) are clear, precise, and rich in hindsight. Charles's arguments (for sending astronauts) are very much based on postulates and theory, and lead way around Robin Hood's barn.

And what I notice from my lifespan is that the machines, from magic telescopes to rovers and Voyagers, have shown us the universe in detail I could only imagine, and wrongly. Today's plans don't put men on Mars within my expected lifespan, and they could be cancelled at the stroke of an election.

But maybe I can hang on long enough to see Pluto. I've come to bet on the machines.

Larry Niven's Science Fiction classics delayed the loss of Jose's virginity

Robots will not have the capacity for a sense of wonder for many decades, I suspect. This aspect of human experience in space--the prospect of personal awe and discovery in the midst of infinite mystery--will propel funding far more over the long haul then robotic exploration, as marvelous as that is. People want to go and explore, not just sit and watch.

Greg Bear is a science fiction author. His work has covered themes of galactic conflict (Forge of God books), artificial universes (Eon series) and accelerated evolution (Blood Music, Darwin's Radio, and Darwin's Children).

As we speak, unmanned space missions are exploring the moons of Saturn, heading to Pluto and the dark reaches of the Kuiper belt, and finding evidence that the Universe is mostly made of stuff we don't understand: dark matter and dark energy. Meanwhile, people aboard the International Space Station have a full-time job just keeping the thing repaired. Promised technological spinoffs like crystals grown in space aren't really amounting to much. The crew made news recently by throwing a space suit stuffed with rags and a radio transmitter into Earth orbit, just so ham radio fans could track it: a clear sign of diminishing returns.

Why are we even bothering with manned space flight? As a character says in Charles Stross' wonderful novel Accelerando, "NASA are idiots. They want to send canned primates to Mars!". This stunt, which will cost billions if we don't stop it, is the scientific equivalent of putting a goldfish bowl on top of Mount Everest.

It would be much smarter to spend the money creating cyborgs who don't breathe and can stand hard radiation; these guys will actually enjoy space travel. We can do this and we can do it quicker than you might guess. In the meantime, let's send machines into space, like the Laser Interferometer Space Antenna. This project, if funded, has a decent chance of seeing gravitational ripples left over from the Big Bang. It's the only known way to see through the wall of fire that cleared up when the Universe was 400,000 years old, back to the first microseconds of history. And it's cheaper than sending canned primates to Mars.

John Baez is a a mathematical physicist who specializes in quantum gravity and n-categories.

As a one-time Astronaut Applicant, and a working space scientist who

works with unmanned science missions, my opinion is that the best space policy is to embrace the power of "and" when it comes to the manned/unmanned mission question. Unfortunately, it has become customary to pit the one against the other. Right now good unmanned missions are being cancelled and delayed because the Powers that Be have decided once again that "science must bear the cost" of the manned space program. This is short sighted, and among many bad things it turns the space community upon itself. We're being divided in order to conquer us. I'm confident that President Bush's Moon/Mars initiative will go nowhere, but in the process of going nowhere it will cause a number of good science programs to be cancelled.

There *are* scientifically sound reasons to put people into space. As others have pointed out, there are also reasons which transcend science. All of these are legitimate reasons to expend our time and treasure on a progressive and reasonable manned space program. It would be nice if someone had such a thing. The current US manned space program suffers from a number of

accumulated problems which have origins back in the late 1940s, and which have become entrenched policy over the course of successive administrations.

Space scientists resent the long-standing practice of raiding the space science programs for money to support the manned space program. Space scientists rightly point out that the International Ultraviolet Explorer accomplished more, at lower cost, than the two ASTRO missions flown aboard Space Shuttle flights. This is but one example of misguided efforts to tie science missions which could be performed by unmanned spacecraft to the manned space program.

NASA is fundamentally an engineering establishment. Scientists have always been in a minority at NASA, and science has never been the main driver in NASA organizational decision making.

While I'm not entirely sure that transfering space science funding to the NSF would be the best solution, I think it would be better than the status quo. NOAA has a nice partnership with NASA whereby they get NOAA weather satellites launched and into orbit. The NSF and NASA could develop a similar partnership that would insure continuting integration, test, and launch

support from NASA while moving the mission operations and data analysis funding out of NASA's budget into the NSF where it more naturally belongs. NASA would be left with manned spaceflight and its too often neglected aeronautical research mission.

Bill Gawne works for a NASA contractor in Maryland and teaches physics and astronomy at Towson University and is a top bloke