If an
outhouse on the Moon ran out of toilet paper, an intrepid settler might have to
waddle about 240,000 miles to get a fresh roll back on Earth.
To make
sure that doesn't happen, scientists have developed a software tool that tracks
and ensures a reliable stream of necessities from the Earth to the Moon.
Released this
month, the computer model, called SpaceNet 1.3, will be critical, say the
scientists, for establishing a human presence on the Moon by 2020, as laid out
in the space vision
by President George W. Bush in 2004.
"The
further away you get from Earth, the
riskier it gets when there are failures of any equipment or shortages of
consumables," said co-researcher Olivier de Weck of MIT. "There aren't many
back-up options."
De Weck and
MIT's David Simchi-Levi developed SpaceNet. The software evaluates several
hypothetical missions to the Moon, with each building upon the previous. It's
set up as a network of nodes that represent either a source of materials, point
of consumption or transfer point for space exploration logistics.
The
resulting supply chain would operate similarly to the flow of materials on
terra firma. But unlike Earth-based delivery service that can suffer delays of
hours or days, goods headed to the Moon
could easily be months late. Just witness the frequent delays in getting a shuttle
to the International Space Station, which is just a little more than 200 miles
away. Plus, shipping capacity will be extremely limited for the expensive,
three-day one-way trip to the Moon.
De Weck describes the dilemma in Earthly terms. "If I sent you on a one-month
trip, and I said you can only pack what fits into your glove compartment, you
would probably still go," De Weck said, "but you'd have a really hard time to
pick what to take with you because there are all of these competing demands."
To help
make these decisions when packing the lunar version of a glove compartment, the
scientists divided supplies into three categories: consumables--such as food,
fuel and water--spare parts and exploration equipment. Like any packing
vacationer, planners with limited space and delivery opportunities will have to
make difficult trade-offs between competing demands for each type of
supply.
"For
example, you could stay for a shorter time, have fewer crew days and bring more
equipment with you. Or you bring less equipment with you but then you stay
longer, and that will require more consumables," De Weck said.
The
scientists will continue to refine and expand SpaceNet, which they say will
ultimately also include a Martian
framework analogous to the lunar version of the software. In another project,
De Weck said they are developing smart containers implanted with electronic
tags to keep track of each shipped item. Of course, the containers would have
the ability to signal to Earth when consumables, such as toilet paper, are
running low.
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