Mike Wall, Space. com (March 25, 2011)
"Spaceships powered primarily by water could open up the solar system to exploration, making flights to Mars and other far-flung locales far cheaper, a recent study has found.
"A journey to Mars and back in a water-fueled vehicle could cost as little as one space shuttle launch costs today, researchers said. And the idea is to keep these 'space coaches' in orbit between trips, so their relative value would grow over time, as the vehicles reduce the need for expensive one-off missions that launch from Earth.
"The water-powered space coach is just a concept at the moment, but it could become a reality soon enough, researchers said....
"...The space coach concept vehicle is water-driven and water-centric, starting with its solar-powered electrothermal engines. These engines would super-heat water, and the resulting steam would then be vented out of a nozzle, producing the necessary amount of thrust.
"Electrothermal engines are very efficient, and they're well-suited for sustained, low-thrust travel, researchers said. This mode of propulsion would do the lion's share of the work, pushing the space coach from Earth orbit to Mars...."
The study's lead author is Brian McConnell, "a software engineer and technology entrepreneur," as the article puts it. Which doesn't mean he knows his physics.
Or that he doesn't.
The idea of using water as reaction mass is old - the stuff's common as, well, as water; is so dense that a lot of mass can be packed into a relatively small tank; and can be stored with fairly common materials.
One reason that we don't have spaceships with water-driven rocket engines is that water also needs a whole lot of energy to heat. Which gets the Lemming into ideas like specific heat, magnetohydrodynamics, and - those are other topics.
- "Commercial Flight to Mars: Maybe, in 15 Years or So"
(September 1, 2010)
- "The Incredible Electric Rocket"
(March 6, 2010)
- "New Rocket Fuel: Aluminum and - - - Water?!"
(October 21, 2009)
- "Rocket Racing League: Really"
(August 3, 2008)
- "Into Space Without Rockets? This Just Might Work"
(January 12, 2008)
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