I believe you are thinking of the aerogel that was used in the Stardust experiment, to send a satellite through the tail of a comet, capture material (with the aerogel), and return it to earth. Because the entire experiement was devoted to samples, the collector medium (aerogel) had to be as free of contaminanats and such as much as possible.JohnsonsEvilTwin wrote:I keep getting different answers on this.
But has anyone heard of AeroGel? But apparently this stuff costs $300,000,000,000(billion) per milligram
http://stardust.jpl.nasa.gov/tech/aerogel.html
Actually, ballast isn't that cheap for racing cars. The standard is tungsten, and it can cost $35 per kilo.
Up here in Toronto we're in the middle of an election for a new mayor, and the buzz is improving transit. The most recent figures bouced around are; a kilometre of light rail costs about $100 million, a kilometre of subway runs around $300 million, and above-ground subways are about $250 million per kilometre.