Did short supplies of oxygen and molybdenum slow down the evolution of animal life? Ancient oceans low on molybdenum would create problems for bacteria that use the element to convert atmospheric nitrogen into a form useful for living things. Brian Wang muses over these matters in his entry in the latest Carnival of Space, referring to a recent Nature paper and moving on to look at potential oceans in the Solar System, from Titan to Callisto, Ganymede, Enceladus, and of course, Europa.
Can life could develop in such places, and if so, how long would it take? Brian frames the question in relation to the Fermi paradox. Perhaps the universe takes a lot longer to evolve complex life than we have been assuming, with implications for what we might find on planets around other stars. We’re shooting in the dark on these questions, unable to say whether life exists off-planet in our own Solar System, but the day may not be so far off when results around nearby planets give us another evolutionary laboratory in which to study biology’s ability to adapt.
Plenty of interesting posts fill this week’s Carnival, but I was particularly taken by Stuart Atkinson’s reflections on Cumbrian Sky, recalling his early fascination with space and reflecting on how we have viewed Mars, and by extension many other astronomical objects, over the past few decades. It’s a long post, filled with reminiscence and reminding us that we can sometimes become all too blasé about the spectacular imagery now flooding the Internet from our space probes. Broadband has changed the landscape. Using his connection and the IAS Viewer available from the HiRISE site, Stuart can see Mars as never before:
“I can go to the HiRISE site, select a picture from the gallery, open it up with the IAS Viewer and literally look down upon single dust-covered boulders, stones and rocks, as if I was being flown over the cratered plains by Peter Pan or Superman.”
Read this post to be reminded of just how remarkable our tools have become, and see if you don’t recognize yourself, as I did, in the space-crazed youth described here.
The Space Access ’08 conference in Phoenix is in its final day, and I notice that bloggers like Henry Cate, Rand Simberg and Clark Lindsey are keeping close watch on events. While the focus is on radically cheaper space transportation, I’ve seen some familiar names from the interstellar community on the agenda, from Gerald Nordley (discussing Tethers Unlimited) to Leik Myrabo, whose work on beamed energy propulsion can translate in the short term into efficient launch systems for Earth orbit, and in the long term into laser propulsion for deep space missions.
LaserMotive‘s Jordin Kare is also presenting, which reminds me of no end of interesting ideas, not the least of which is Kare’s SailBeam, a proposal to send tiny ‘micro-sails’ pushed by laser to drive an interstellar craft. The idea is a form of pellet propulsion of the sort first proposed by Clifford Singer back in 1979 and later developed into Gerald Nordley’s exquisite ‘snowflake’ pellets, using nanotechnology to steer their own course. Kare’s take was to cross pellets with lightsails, with each micro-sail becoming part of the fuel stream for the outbound spacecraft.
Why not a full sail? Kare realized that if you cut a large sail into tiny pieces and accelerate those fragments one after the other, you could bring the same amount of mass up to speed using a much less demanding optical system. The small sails can be accelerated much faster close to their power source, an idea that does away with deployment and maintenance issues in large sailcraft. The interstellar vehicle could use an onboard laser to vaporize the sails into plasma as they approached, deploying a pusher plate or magnetic field to absorb the energy.
Talk about acceleration — Kare’s diamond film sails would accelerate to close to light speed within seconds under an acceleration of thirty million gravities. The study Kare did for NASA’s Institute for Advanced Concepts, called “High-Acceleration Micro-Scale Laser Sails for Interstellar Propulsion,” is still available at the NIAC site even though the Institute is no longer in operation. For more, see this earlier Centauri Dreams post.
What I need to do next, now that Space Access ’08 has taken me so far afield from my earlier posting plans today, is to treat Kare’s interesting ‘fusion runway’ concept, one that would use impact fusion to accelerate a spacecraft to speeds that would make an interstellar journey possible. But I’m low on time, so we’ll get to that one down the road. How can I not discuss a propulsion system its designer refers to as the ‘Bussard Buzz Bomb?’ I’ll explain the origins of that name in the upcoming article.