Astronomer*
We need to spend a lot of money to develop ways to keep people safe on another planet and provide them with ways to get food, air, and water (including recycling what they bring with them).

Douglas Scott
Professor
University of British Columbia
I think this will be extraordinarily difficult. We should focus on keeping our own planet in good shape!

Dr. Michael M. Davis
Astronomer
SETI Institute
All the usual things, like how to survive in a harsh environment, and how to make use of
available materials. More importantly, I think, we will have to learn how to get along with one another under very difficult conditions -- at least to begin with. Check out the Mars project at www.seti.org. Pascal Lee is the principal investigator.

Yervant Terzian
Professor
Cornell University
We must find a 'paradise' with a friendly ecosphere, that has oxygen in the atmosphere and liquid water.

Prof. Wayne G. Roberge
Theoretical Astrophysicist
Rensselaer Polytechnic Inst.
Our biggest problem today is that it is VERY expensive to transport materials into space: it costs about $10,000 per kilogram. This is mainly because most of what an expensive rocket carries is its own fuel. People are working on clever ways to get around this. For example, one professor here at Rensselaer is trying to use lasers on the ground to push spacecraft into orbit. The advantage is that the heavy, expensive laser stays on the ground.

Astronomer*
1. Find an earth-like planet or have the technology or means to "tera form" a planet.

2. Space flight technology to get there fast enough, safe enough, and/or preserve us long
enough.

3. Manage not to kill ourselves (or get killed by some other natural disaster) before any of these technologies can be invented or used.

Andrew Liddle
Astronomer
University of Sussex, UK
We could inhabit Mars on the moon now if enough money was put towards the project. I doubt it would be worth it though.

Karen Vanlandingham
Assistant Professor
Columbia University's Biosphere 2 Center
1. How to establish and maintain a habitat. If we are to live anywhere else we have to be able to duplicate the conditions here on Earth.
2. Space travel. Unless we stay in our solar system (and even then we'd have to stay close by) it would take us too long with current technology to get anywhere.

Don Brownlee
Astronomer
University of Washington
The biggest difficulties are getting there and making an environment that we could live in.
It is possible that neither of these can be done in any practical sense.

Astronomer*
Merely the will to do it. We have the ability at this time to inhabit the moon or perhaps Mars. What we lack is the collective drive to expend the resources. The seeds of this will exist in our efforts to inhabit nearby space on a space station. It may take time, but I believe that eventually we will get there.

Eilat Glikman
Graduate Student
Columbia University
Earth is our home. We evolved to fit the Earth's environment - not the other way around. So in order to switch things we have to make a planet evolve into our needs! We would have to make our new home as earth-like as possible. Perhaps once we do, millennia will pass and humans will evolve to better adapt to their new home. But to make it at first we would have to be someplace that was as similar to Earth in every possible way.

Professor*
We need to get there and to set up (probably) self-sustaining colonies. To do this on the Moon or Mars requires not a lot of technological development beyond what we have now.
The main problem is cost. It would cost more than governments are willing to spend.

Walter Harris
Astronomer
University of Wisconsin-Madison
Actually we can probably do it now if we want to. I don't think that colonizing the Moon
would be a greater enterprise than colonizing the new world was for Europe. We can already get to the moon and communicate with people there many times faster than we could travel/communicate between New York and Paris 200 years ago. Whether we do it or not depends on what we are willing to invest in the project. It won't be cheap.

Some new technologies would help us make the decision to go sooner. In particular we need to find a way to get things into orbit more cheaply. The Space Shuttle costs about $10,000/lb to fly things into space. That's awfully steep. New technologies on the horizon may get that down to $100/lb, and that may be the point at which people are willing to give colonizing a try.

Once we do go, we will need to develop better ways to process air and water from local
materials and to generate power. We know in principle how to do make air and water, but it would get even easier if there is water ice trapped on the moon (which we think there may be) or Martian permafrost. Nuclear or solar power would be good bets for a generator based on current technology, but fusion power (which we have not yet been able to make work effectively) would be better still.

This all supposes we want to go somewhere in our solar system. If we want to inhabit a planet in another star system, we are going to need to develop fast space travel or learn how to build giant space 'ark' transports that take generations to reach their target stars. Neither of these are even on the drawing board yet.

Steven Novotny
Air Force Officer/Graduate Student
University of Florida Astronomy Department
Reasonably cost launch systems - lessen the price to put something into orbit. This will probably require new types of engines or fuels.

Bob Mathieu
Professor of Astronomy
Department of Astronomy, University of Wisconsin - Madison
Whew, Cassy, that's a big one that I can't answer completely here. But one thing to keep
in mind is that there are many different distances in the universe. First there is our Solar
System, all of which is close by. Its quite conceivable that we will travel to other planets
and moons and set up permanent homes. Then there are the distances to the stars. Even if we travel at the speed of light, it will take us a few years to get to the very nearest star ...and we don't know how to travel that fast yet. Until we do, it is very unlikely that we will reach the nearest star anytime soon. The only hope would be building a space ship that could allow many generations to survive the trip. But that is just the nearest stars. The other stars in the galaxy are many thousand times further away. And the nearest galaxy like our own is a million times further away than the nearest star. So really, asking your question about inhabiting another planet or moon in the universe is perhaps looking a bit too far - for a while let's stick with our Solar System!

Professor Rex A. Saffer
Physicist, Astronomer, Educator
Dept. of Astronomy & Astrophysics, Villanova University
First we will need to find planets or moons that have the things we need (Goldilocks!) to
survive - suitable temperature, water, and gaseous oxygen. OR - at least materials that we can make these from if we have an energy source. We also need to learn how to live in space for long periods of time to get to these planets or moons. Also we would need to learn how to live with each other better!

Martin Duncan
Professor of Physics
Queen's University, Canada
Very efficient ways of traveling very fast and surviving for extended period in space (space cities or colonies in flight?)

James Pantaleone
Professor of Physics
University of Alaska Anchorage
The Earth has tremendous biological recycling capabilities that we take for granted. These would have to be recreated to allow humans to stay in space or on a moon or plant for many years. We really can't do that yet.

David Batuski
Astronomer
University of Maine
How to cover great distances quickly.

Astronomy Professor*
First we'll need the desire to do it and second the funding to accomplish it. The technological and engineering problems are minor compared to desire and funding.

John Huchra
Astronomer/Professor
Harvard-Smithsonian
Patience. Probably the ability to travel at or above the speed of light. Possibly ways of increasing the human lifespan and avoiding boredom on long trips!

*Respondents opted for anonymity and we respect their wishes.