A mission trajectory study estimated that a VASIMR-powered
spacecraft could reach the red planet within 40 days if it had a
200 megawatt power source. That's 1,000 times more power than what the current
VASIMR prototype will use, although Ad Astra says that VASIMR can scale up to
higher power sources.
The real problem rests with current limitations in space
power sources. Glover estimates that the Mars mission scenario would need a
power source that can produce one kilowatt (kW) of power per kilogram (kg) of
mass, or else the spacecraft could never reach the speeds required for a quick
trip.
Existing power sources fall woefully short of that ideal.
Solar panels have a mass to power ratio of 20 kg/kW. The Pentagon's DARPA
science lab hopes to develop solar panels that can achieve 7 kg/KW, and stretched
lens arrays might reach 3 kg/KW, Glover said. That's good enough for VASIMR to
transport cargo around low-Earth orbit and to the moon, but not to fly humans
to Mars.
Ad Astra sees nuclear power as the likeliest power source
for a VASIMR-powered Mars mission, but the nuclear reactor that could do the
job remains just a concept on paper. The U.S. only ever launched one nuclear
reactor into space back in 1965, and it achieved just 50 kg/kW.
More than 6,000 different species living on the sea-floor have been identified so far and more than half of these are unique to the icy continent. A combination of long-term monitoring studies, newly gathered information on the marine life distribution and global ocean warming models, enable the scientists to identify Antarctica's marine "biodiversity hotspots". Researcher Griffiths describes how krill populations (the shrimp-like invertebrates eaten by penguins, whales and seals) are reducing as a result of a decrease in sea-ice cover. A much smaller crustacean (copepods) is dominating the area once occupied by them. This shifts the balance of the food web to favour predators, like jellyfish, that are not eaten by penguins and other Southern Ocean higher predators. Sea-ice reduction is also affecting penguins that breed on the ice.
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