Return to Flight – May 27, 2020


It’s Science Wednesday – and today is a historic day in spaceflight! For the first time in nearly a decade, US astronauts are launching from US soil again. Not only that, this is the first-ever manned launch for SpaceX in its 18-year history and the first time ever that a privately developed spacecraft will launch humans into Earth’s orbit. The two astronauts aboard the Demo-2 are NASA veterans – Robert Behnken and Doug Hurley, who served as pilot on the shuttle Atlantis for its final flight in 2011.

The coastal region of Florida, home to the Kennedy Space Center, offers a number of logistical advantages for launch. This includes proximity to the ocean, so rocket debris can fall into the sea, and the Equator, which makes launches more efficient. Imagine you’re on a merry-go-round with your friend. She is near the middle and you are on the edge. You both have the same rotation rate (angular velocity) but since you have a much greater distance to go (all the way around the outside), you have to go faster.

If the magnitude of the angular velocity is represented by ω then the speed will be: v = ωr, where r in this case is the distance from the axis of rotation. Now suppose you try to launch a rocket from the North Pole. In this case, the distance from the axis of rotation would be zero meters. You would get no “speed bonus”. The speed “boost” comes at the equator since that is the farthest from the axis of rotation. When it costs thousands of dollars per kilogram of cargo and fuel, every bit of energy savings helps!

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photo: U. Horodyskyj