functioning at full capacity. Developing a bioregenerative life support system based on
such “programmable plants” is not only key to human expansion into the solar system, it
is now also scientifically tenable by bringing together the emergent disciplines of ge-
nomics, nanoscience, biosensor technology, robotics, and intelligent machines.
Combining these disciplines with our ever-expanding understanding of how plants sense
and respond to their environment, as described in the previous chapters of this book, will
allow manipulation of plant growth and development to sustain a human presence in
space.
9.2 Human missions to space
There are multiple reasons for sending humans into space, including scientific research,
economic benefit, and psychological satisfaction derived from fulfilling the quest to ex-
plore and extend the human frontier. It is possible that in the distant future, mankind will
have to colonize space as Earth becomes overcrowded or uninhabitable. It is inevitable
that the exploratory missions will become outposts, outposts will become colonies, and
colonies will become self-sustaining, independent, and permanent. For this to occur, all
the elements of life support and permanent presence must be available and/or produced
in situ. Short of this, human settlements in space will remain forever outposts, utterly de-
pendent on Earth.
One such space destination is Mars. Overall, the conditions on Mars are not so radi-
cally different from Earth (Carr 1996). It has been proposed that biological activity could
be supported with some protective structure (Wheeler 1999). Although it is unlikely that
there is life on the surface of Mars at present (McKay 1997), there is evidence that it may
have existed there in the past (McKay et al. 1996). This compelling, yet controversial,
speculation constitutes just one among many of the reasons for going to Mars, i.e., to
search for clues of extinct or extant life. Other near-term human settlements in space in-
clude a permanent low-Earth-orbit station (currently the International Space Station) and
the Moon. The success of these settlements will require a long-term human presence in
space and on planetary surfaces other than Earth’s, which, of course, will require a ro-
bust, adaptable, and controllable life support system.
9.3 Life support
The four basic functions of any human life support system are to provide:
- Suitable atmosphere;
- Clean water;
- Food;
- Waste processing.
Essentially, the options for life support are either re-supply or regeneration. Re-supply
is simple to explain—essential survival supplies are shipped from Earth. As described