The orientation also makes for a much lower center of gravity than a typical fuel-cell car.

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Lifting heavy spacecraft and fuel out of the Earth's gravity is expensive.

CNN: Bush: 'It is time for America to take the next steps' in space

Scientists said they launched the satellite from midair to save money, compared with an expendable rocket launched from the ground, because it doesn't take as much fuel to break free of the planet's gravity.

WSJ: NASA NuStar Telescope to Hunt for Black Holes