SpaceX’s Falcon 9 Rocket Gets Its Legs

“All four landing legs now mounted on Falcon 9…”

Wait! What??!

That was SpaceX CEO Elon Musk’s tweet on 25 February, 2013.  And there was a linked picture of it all, too.

SpaceX is doing something NASA and the United States Air Force can’t do:  adding legs to its Falcon 9 rocket.  That’s right, the gradual successful steps during tests of SpaceX’s Grasshopper Vertical Takeoff Vertical Landing vehicle (videos of launch and landing below) is encouraging SpaceX to take the next logical step of adding legs to its bigger rockets.  Why?  Because SpaceX would like to eventually not only launch its rockets, but also land them.  Not landing them like a shuttle–but landing them nearly the same way the rockets are launched:  vertical, with the fiery side aimed down.  Then SpaceX believes it has everything pretty much nailed down for reusable launch vehicles.

If SpaceX is successful in making rockets reusable, then it means the company’s $54 million price tag to launch objects into space will be much lower.  In comparison, according to a 2004 Space Systems Forecast paper, the Air Force’s Evolved Expendable Launch Vehicle (EELV) costs on average $149.6 million per launch vehicle (probably more, now), not including space launch complex upgrades.  Space suddenly becomes affordable for many more companies.

Another anticipated benefit of SpaceX’s Falcon 9 rocket legs design?  Quick launch turnaround times.  SpaceX thinks it will be fairly easy to get a rocket that just landed all fueled up and ready to go.  This may depend more on external regulations than what SpaceX can do.  Certainly, it wouldn’t take very long to go over the rocket, like a pilot inspects an airplane.  Then refuel it, and send it back up.  Quick turnaround would also be key to cutting costs in space launch, as the less time the rocket spends on the ground being cared for by maintainers, engineers, and so on, the less money SpaceX spends on that sort of thing.  But again, that also may depend on what kind of regulation changes SpaceX can wrangle from the Air Force and US government.

SpaceX has already tried some interesting things with its Falcon 9 rocket.  On September 29, 2013, SpaceX launched a Falcon 9 to deliver the Canadian CASSIOPE satellite into orbit.  Already, before the launch, there was plenty to talk about.  Among the many different new designs and items on this particular Falcon 9, SpaceX had fitted it with brand new, more powerful, rocket engines—9 of them.  Those engines were also placed in a much different configuration using a structure SpaceX calls Octaweb.  This was so new, SpaceX gave a hefty discount to the Canadian satellite owners as a way to offset the potential risk of these new technologies.

When Falcon 9 was launched, everything worked and the satellite was placed in orbit.  But, and here’s where the legs come in, SpaceX also tried something a little different with the rocket stages during that launch:  relighting them.  SpaceX successfully relit both stages, something no other launch company has done with their rockets—at least on purpose.  Relighting a stage implies the stage can possibly be controlled in its descent towards the Earth.  The second stage was relit only once, but had a few issues.  The first stage relit twice, with SpaceX attempting to control the stage enough for it survive reentry through Earth’s atmosphere.  SpaceX seemed happy with that first stage controlled descent attempt.

From SpaceX’s “News” page about that mission:  “This particular stage was not equipped with landing gear which could have helped stabilize the stage like fins would on an aircraft.”  This means that the addition of legs on SpaceX’s Falcon 9 serves two purposes.  First, the legs will help stabilize the first stage during reentry.  Second, and more obvious, is for the legs to extend, giving the base of a rocket around a 60 ft span, and help the rocket land safely back on the launch pad.

The particular Falcon 9 rocket legs Mr. Musk tweeted about is meant to launch the International Space Station’s servicing and resupply flight.  And in an earlier tweet, Mr. Musk has stated that Falcon 9 will continue to use the ocean as the rocket stages landing area until SpaceX has proven they have full control of the stages “from hypersonic thru subsonic regimes.”

They will be testing a Falcon 9 Reusable (F9R) landing prototype, probably at SpaceX’s McGregor, Texas facilities, for low altitude flights.  Then SpaceX will move F9R to Spaceport America in New Mexico for high altitude testing.  Roswell might yet see hovering spaceships and flame in the skies—real ones.