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One could argue that the US's appeasement of environmentalists in using liquid Hydrogen has cost us 14 astronaut lives.

The Russians stuck with petrolieum based fuels (Kerosine) in their rockets including their workhorse of manned spaceflight, the Soyuz rocket. It's safety is legendary due primarily to it's simplicity.

The US space shuttle was directed to use liquid Hydrogen back in the 1970s principally to counteract complaints about how previous petrieum based rocket propellants "harmed" the environment. Cryogenic rocket engine technology is tricky and dangerous.

The reason that there is insulation on the External Tank is to keep the cryogenic liquid Hydrogen from boiling off. The Russians don't worry about chunks of foam and ice falling off of their rockets.

The recent change in ET insulation foam was driven by the edict to not use Freon in the foam manufacturing process. The non-Freon foam isn't as structurally sound as the Freon foam, and tends to flake off during launch like what hit the Columbia orbiter's left wing.

The Russians also stick with all room temperature liquid propellants, that lets them launch reliably in all kinds of weather (including blizzards.) The shuttle has solid rocket boosters (with suspect o-rings between the segment joints), to give the shuttle an extra boost of thrust. Since Hydrogen is so light, it is high on exhaust speed (Isp), but low on thrust (Ft), therefore has great performance once you get moving out in space, but not so great at liftoff.

So next time you see a protesting eco-fascist, remind them that their political push for Hydrogen killed the Challenger and Columbia astronauts.*

* For propaganda purposes only, but grounded in more scientific fact than any eco-fascist will use to support the use of Hydrogen.

Hydrogen back in the 1970s principally to counteract complaints about how previous petrieum based

Thought I read that lH2 was used because of highest available energy for any liquid fuel (by weight).

Good points.