The 28th carnival of space is now online at the Planetary Society's blog.
An especially interesting entry is about
collecting natural antimatter.
Antimatter readily annihilates when it contacts with normal matter, and releases the whole energy corresponding to its mass (E=mc2). This makes it especially useful for spacecraft propulsion.
The recently finished report for the Nasa Institute for Advanced Concepts says:
For example, 100 nanograms of antiprotons can be used to catalyze sub-critical nuclear reactions and drive a one metric ton of payload to 100 km/sec. [...] In comparison, if traditional chemical propellants were used for the same task, nearly 109 metric tons of hydrogen and oxygen would have to be launched into space.
And that would mean about 500,000 shuttle launches.
Currently antimatter is generated at CERN and Fermilab, with capacities about 1 nanogram/year (10-9 grams). The production costs are estimated to be about $100 trillion per gram.
The report investigates trapping and collecting the naturally produced antimatter in the environment of Earth and the other planets. It claims it would be both technically feasible, and would be able to bring down the cost of antimatter production by 5 orders of magnitude.