Sky and Telescope - July 2018 - 40
maximum, its wind stretches out
from one orbit to another would
Earth's atmosphere. As high-denrequire too much fuel to be practisity air reaches higher altitudes, it
cal, so tugs would have to stay at a
clears out much of the LEO debris.
narrow range of inclinations.
Further, simulations show that
Nevertheless, in the long run
the biggest contributors to a KesI expect we'll see a ﬂeet of space
sler cascade would be the largest
garbage trucks sidling up to longsatellites. The Iridium-Cosmos
dead spacecraft and nudging them
collision is a case in point - it's
to their doom. Or, perhaps, sendthis sort of crash that makes the
ing them to very high orbits, where
most debris. So maybe we should
the low orbital velocities make it
focus on getting rid of the moncheaper to change inclination. You
ster space junk ﬁrst; there's less of
could potentially collect billions of
it, so that's an easier problem.
dollars of defunct high-tech matep INVENTION OF NECESSITY The Cleanspace One
We will soon have the techrial in an orbital scrapyard, where
concept, which features a Pac-Man-like mechanism for
nology to do just that. Building
materials could be recycled.
capturing space junk, is one of many inventive ideas on
the drawing board for dealing with orbital debris.
on the collective experience in
At this point, the challenge has
sending robotic cargo ships to the
become more political and economInternational Space Station (ISS), companies may soon build
ical than technical. I believe that some kind of international
satellites to grab onto and repair or refuel communications
tax on satellite operators will be needed to fund the orbital
payloads, even those that - unlike the ISS - weren't designed
cleanup system. As usual with environmental problems, it's
for visitors. Such space tugs could also move their prey to a
one thing to realize we have a disaster on our hands - it's
different orbit, perhaps sending them down to controlled
quite another to agree to do something about it. Let's hope we
reentry over the ocean.
still have space exploration a century from now!
But whose stuff can you deorbit? NASA, for example,
would be allowed to deorbit its own space junk, but the legal¢ In addition to studying black holes and devising data-analyity of grabbing onto someone else's dead satellite is questionsis software, astrophysicist JONATHAN MCDOWELL (Harvardable, even if it belongs to a country that no longer has a space
Smithsonian Center for Astrophysics) is an avid investigator
program. Space lawyers are already talking about this issue!
of space history. His free online newsletter, Jonathan's Space
Space tugs wouldn't come cheap, either. Different satellites Report, has provided technical details of satellite launches
ﬂy at various orbital inclinations to the equator. Changing
since 1989. Find out more at planet4589.org.
SPACE JUNK? The Tesla Roadster and its dummy occupant, dubbed
Starman, which were launched into a solar orbit earlier this year, weren't
the first objects left in interplanetary space.
J U LY 2 0 1 8 * S K Y & T E L E S C O P E
CLE ANSPACE ONE: WIKIMEDIA COMMONS / CC ASA 4.0; TESL A ROADSTER: SPACE X