IEEE Spectrum June, 2014 - 88

continued from Page 39 | mining outfits-but for water. The firm
expects to extract it from some kinds of asteroids simply by using
heat from concentrated sunlight, says Chris Lewicki, the company's
president and chief engineer. "Our focus isn't necessarily on inventing new technology," he says. "It's on doing with a small team what
once used to take the government."

gAthering r Aw mAteriAls is only the beginning. to
build up infrastructure, we must also develop ways to fabricate
and manipulate structures in space.
The U.S. Defense Advanced Research Projects Agency has been
making headlines with the Phoenix project, which would use advanced robotics and modular components to construct spacecraft in
orbit. Among other uses, this combination could extract the antenna
from a defunct satellite and build a new one around it.
A company called Tethers Unlimited, based in Bothell, Wash.,
hopes to fabricate structures from scratch, on even larger scales.
Its project, called SpiderFab, aims to use robotic arms to build
up and maneuver across 3-D-printed structures while floating
free in orbit. The goal is to create objects that are too big to be
folded into the top of a rocket. "What we're trying to do is figure out how to make it not ridiculous to talk about antennas
that are hundreds or thousands of meters in diameter," says
CEO Robert Hoyt. One of the biggest challenges Tethers is tackling now is how best to manage the thermal environment, Hoyt
says. The temperature can vary by hundreds of degrees in orbit,
and large temperature gradients could prevent structures from

properly cooling and hardening, causing wild deformations.
The first 3-D printer to go into space won't suffer such problems.
Built by Made in Space, a start-up based in Moffett Field, Calif., and
set to be delivered to the International Space Station later this year,
it will be safely ensconced in a climate-controlled glove box. The
printer makes objects out of heated polymer filament, just as many
terrestrial 3-D printers do, but it has been altered to work in microgravity. The team logged hundreds of hours on parabolic flights to
perfect the technology, says lead engineer Michael Snyder, but he
won't disclose what sets it apart from typical 3-D printers. "That's
our special sauce," he says. The company plans to send an improved
version of the printer to the station in 2015 and rent time on it to
anyone who might want to print in space.
Both SpiderFab and Made in Space printers would require carrying material up from Earth to be used as the raw material for
construction. Printing structures using material gathered elsewhere is still on the horizon. Although the European Space Agency,
NASA, and others have looked into building very crude structures-
mostly human habitats and landing pads-out of lunar soil, at present there are no plans to try out these ideas in space.
Still, many say the basic ingredients needed to build a true space
infrastructure are more or less ready. Now we must find a way to
combine them. Only then will our machines be able to prepare the
way for our own forays to the moon, the planets, and the stars, turning us at last into a truly spacefaring species. n
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Table of Contents for the Digital Edition of IEEE Spectrum June, 2014