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.
thinkahol * on 19 Oct 11Brain, bodily awareness, and the emergence of a conscious self: these entities and their relations are explored by Germanphilosopher and cognitive scientist Metzinger. Extensively working with neuroscientists he has come to the conclusion that, in fact, there is no such thing as a "self" -- that a "self" is simply the content of a model created by our brain - part of a virtual reality we create for ourselves. But if the self is not "real," he asks, why and how did it evolve? How does the brain construct the self? In a series of fascinating virtual reality experiments, Metzinger and his colleagues have attempted to create so-called "out-of-body experiences" in the lab, in order to explore these questions. As a philosopher, he offers a discussion of many of the latest results in robotics, neuroscience, dream and meditation research, and argues that the brain is much more powerful than we have ever imagined. He shows us, for example, that we now have the first machines that have developed an inner image of their own body -- and actually use this model to create intelligent behavior. In addition, studies exploring the connections between phantom limbs and the brain have shown us that even people born without arms or legs sometimes experience a sensation that they do in fact have limbs that are not there. Experiments like the "rubber-hand illusion" demonstrate how we can experience a fake hand as part of our self and even feel a sensation of touch on the phantom hand form the basis and testing ground for the idea that what we have called the "self" in the past is just the content of a transparent self-model in our brains. Now, as new ways of manipulating the conscious mind-brain appear on the scene, it will soon become possible to alter our subjective reality in an unprecedented manner. The cultural consequences of this, Metzinger claims, may be immense: we will need a new approach to ethics, and we will be forced to think about ourselves in a fundamentally new way. At
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