Testimony of Dr. Robert Zubrin to the Senate Commerce Committee, Oct 29, 2003

Jim Whitehead ejw at cse.ucsc.edu
Wed Nov 12 16:53:27 PST 2003


Eugen Leitl writes:
> However, the case stands for its own. In absence of autonomous
> robots, lunar fabbing teleoperation is the cheapest and safest
> way to bootstrap massive industrial capabilities.

It seems to me that there are different fundamental goals and assumptions at
play here.

That is, do you want to create a new location for humans to live? Or do you
want to contribute to economic activity on Earth? Is space exploration
something that can be economically sustainable, or is it something that only
governments can afford to do for the forseeable future? These seem to be the
fault lines of the debate.

> > * Martian atmosphere protects against solar radiation -- handy during
>
> Rad-hard automation doesn't have a problem with solar radiation.
> Lunar soil protects far better against radiation than a thin atmosphere
> ever could.

If your goal is to create new living spaces for humans and you want this
living space to be on the surface, then you'll want a radiation-safe
location to live, on the surface.


> > intense solar flare activity. This protection makes surface greenhouses
> > easier to create, since you need less shielding in your glass.
>
> Glass greenhouses?! Did you look at the forces on the glass? This is
> expensive beyond belief, and rather unsafe (blowouts due to structural
> failure and micrometeorite erosion).

The assumption is that you'll want to directly capture sunlight, since
otherwise it is extremely energy intensive to replicate the W/m of sunlight
for plant growth. Even with massive machine replication, energy costs will
simply be less, they won't go to zero.

> > * The Martian day is more amenable to greenhouses, since the
> Martian day is
>
> Martian insolation is but a fraction of the solar flux.

Use magnifying lenses built in to the dome over your greenhouse. It's far
cheaper to build a  magnifyer than to create a huge solar energy
infrastructure.

> There's permanently insulated areas on the lunar poles, where the hydrate
> cryotraps are. This is where you start the colonization.

Yes, but people would be living under the surface. Once you could
manufacture very large underground caverns, this wouldn't be so bad. But,
early on, it'd be miserable living in underground tin cans all the time.


> > * Mars has more readily accessible water sources than the Moon.
>
> Machines don't need water.

Yes, but even you are discussing colonization, and that means people.

> > * The Martian atmosphere can be leveraged in many ways to provide fuel,
> > combution material (for CO2-driven combustion cycles), etc.
>
> Combustion? In space? What for?

Surface transportation, for one. Combustion engines allow for conversion of
high energy denisty fuels into kinetic energy. Electric isn't as good, and
at present neither are fuel cells.

> DeltaV assumes material transport. Bootstrap by teleoperation and
> automated fabbing very much eliminates material transport. Initial
transport is
> Earth->Luna, one way. After that, it's Luna->Earth, via linear
> mass drivers and aerobraking and/or ion/plasma braking.

This strikes me as naive. Any plan will involve large #s of tons of
material.

> Radiation is an issue on 6 month transit to Mars.

Increased radiation-induced cancer risk is fairly low for the transport.

> Being an astronaut is even more dangerous than being a
> lumberjack. No canned monkeys = no human risk. This way you can tolerate
> high failure rates during launch.

Certainly it makes sense to use automation, where possible. However, I still
view the purpose of going to Mars getting people on the surface. At present,
the robotics of Pathfinder and MER is primitive as compared to a person. I
imagine that all the data recorded by Pathfinder could have been
accomplished *much* faster by a human. Humans have far more initiative as
well.

> How do you know which industrial process I want to perform? Give
> me a list of stuff you want to do; I'll show you that you can do it
> in a vaccum much better.

OK, how will you do this on the Moon?
* create soil for greenhouses
* create tubes of pure silicon
* create hydrogen-based rocket fuels

> Yes, they will be very tricky indeed. Let's say I want to melt regolith to
> sputter semiconductors on top of it, to quickly create solar cell
> arrays some km^2 sized (you will need more of than on Mars, because the
> insolation is less then).

The primary energy sources on Mars at first would be nuclear and combustion.

> What would you do with power on Mars, I wonder? No way to beam it
> to Earth.

Harnessed power on Mars is far too valuable for activities on Mars to send
it off-planet.

> I thought, that was the whole point of industry in space: it
> results in ROI, quick, lots of it.

I don't think space activities will have positive ROI for generations. I
think it's best not to even couch space activities in these terms, since
poor ROI would lead to retrenchment of space activities. I think space
industry does fit the capitalist model, but at a scale only governments can
afford (high billions of investment yield trillions over a long time span).

That all said, it appears lunar space activity may win the day in the Bush
Administration:
http://www.spaceref.com/news/viewnews.html?id=894

- Jim



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