Energy and Human Ambitions on a Finite Planet, 2021a

4 Space Colonization 59
to eat. 17 Think about it: where would you go to grab a bite in our solar
system at present, outside of Earth? And a solar system is an absolute
oasis compared to the vast interstellar void. The two factors that jointly
promoted evolution onto l<strong>and</strong> <strong>and</strong> into the air will not operate to “evolve”
us into space. It’s a much tougher prospect. Yes, it could be possible to
grow food on a spacecraft or in a pressurized habitat, but then we are
no longer following the evolutionary meme of stumbling onto a good
deal.
17: Amusingly, consider that no cheeseburgers
have ever smacked into a space
capsule.
One “win” some imagine from space is
access to materials. Yet Earth is already wellstocked
with elements from the Periodic
Table, <strong>and</strong> the economics of retrieval from
space are prohibitive in any case.
Box 4.3: Accomplishments in Space
Before turning attention to what we have not yet done in space,
students may appreciate a recap of progress to date. The list is by no
means exhaustive, but geared to set straight common misconceptions.
◮ 1957: Sputnik (Soviet) is the first satellite to orbit Earth.
◮ 1959: Luna 3 (Soviet; unmanned) reaches the moon in a fly-by.
◮ 1961: Yuri Gagarin (Soviet), first in space, orbits Earth once.
◮ 1965: Alexei Leonov (Soviet) performs the first “space walk.”
◮ 1965: Mariner 4 (U.S.; unmanned) reaches Mars.
◮ 1968: Apollo 8 (U.S.) puts humans in lunar orbit for the first
time.
◮ 1969: Apollo 11 (U.S.) puts the first humans onto the lunar
surface.
◮ Pause here to appreciate how fast all this happened. It is easy to
see why people would assume that Mars would be colonized
within 50 years. Attractive narratives are hard to retire, even
when wrong.
◮ 1972: Apollo 17 (U.S.) is the last human mission to the moon;
only 12 people have walked on another solar system body, the
last about 50 years ago.
◮ 1973–now: as of this writing (2020), humans have not ventured
farther than about 600 km from Earth’s surface (called low
earth orbit, or LEO; see Figure 4.4) since the end of the Apollo
missions.
◮ 1981–2011: U.S. operates the Space Shuttle, envisioned to make
space travel routine. After 135 launches (two ending in catastrophe),
the shuttle was retired, leaving the U.S. with no human
space launch capacity.
◮ 1998–now: The International Space Station (ISS) [30] provides
an experimental platform <strong>and</strong> maintains a presence in space. It
is only 400 km from Earth’s surface (4-hour driving distance),
<strong>and</strong>—despite its misleading name—is not used as a space-port
hub for space travel. It is the destination.
ISS
HST
Figure 4.4: The pink b<strong>and</strong> indicates the farthest
humans have been from the surface
of the earth for the last ∼ 50 years. The
Hubble Space Telescope (HST) orbits at the
top of this b<strong>and</strong> at 600 km altitude, <strong>and</strong> the
International Space Station in the middle
at 400 km. Beyond the thin black line outlining
the globe, Earth’s atmosphere is too
tenuous to support life.
[30]: (2020), International Space Station
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.