This morning everybody and their dog is reporting on the achievement of Jeff Bezos’s Blue Origin rocket company, but they’re doing it wrong.
“Jeff Bezos beats Elon Musk’s SpaceX in the reusable rocket race” was Engadget’s headline, while Gizmodo added “take that, SpaceX” in its facebook commentary, and PopSci breathlessly titled their report “Blue Origin Beats SpaceX In Landing Reusable Rocket.”
The problem is they aren’t even in the same race.
Blue Origin is trying to, in the words of Randall Munroe, get to orbital height. SpaceX is trying to get to orbit. The difference is about 17,000 miles per hour sideways. I’ll explain.
Basically, the way orbiting the Earth works is that you’re moving so fast sideways that as you fall toward the Earth you continually “miss.” The curve of your fall always pulls you out of the way of the Earth. That (very fast indeed) speed sideways is called orbital velocity, and it’s the hardest part of getting to orbit. In order to get to orbital velocity, your rocket goes up a little and sideways a lot.
Orbital velocity, by the way, is the reason things burn up in the atmosphere. Just falling from a great height won’t get you going fast enough to burn up, because the air slows you down to your own personal terminal velocity. This is why a man can parachute from a balloon at the edge of space, but astronauts can’t parachute down from the International Space Station. This is also why, once you’re at orbital velocity, it’s really impractical to “just” use a rocket to land.
What Blue Origin is doing is going straight up and coming straight down. They’re a lot like SpaceX’s grasshopper tests, but with a higher altitude. And the rockets are reusable. This is super useful for lowering the cost of space tourism (which is excellent), but not useful for getting things like satellites or people into orbit.
What SpaceX is trying to do is get satellites and things into orbit while reusing the rockets, which is very, very different. First, it’s really impractical to “boost-back” from orbital velocity because you’d need to boost all that extra fuel up there in the first place. So SpaceX’s Falcon 9 R rocket “just” has a reusable first stage. This detaches at about 80km up and at about 7600 mph, reaches apogee at 140km up, and starts its engines back up to slow down further at around 70km. Once it’s in “re-entry” — something parachutists and Blue Origin’s rocket don’t need to deal with — it has guidance fins (“grid fins”) which steer it to its new location (at this point a barge with an endearing name) before the final burns which attempt to land it safe and sound.
Blue Origin has indeed completed its return safely. SpaceX has not (yet). But the two are very different things, and not really even worth comparing. They’re both done by hard-working and very intelligent people with very different goals.
So congratulations to the Blue Origin team on a very successful trip to orbital height and back. And best of luck to SpaceX in December (we hope) for another test of a trip to (roughly half) orbital velocity and back. I can’t wait.
Update (25 Nov 2015): I had originally reported that the New Shepard used parachutes to descend to 5000 feet before engaging its engines to land, when in fact it is only the capsule that uses chutes. The New Shepard booster does not, and lands under its own power. This post has been updated to reflect these changes.
Richard Ford Burley is a writer and doctoral candidate at Boston College, as well as an editor at Ledger, the first academic journal devoted to Bitcoin and other cryptocurrencies. In his spare time he writes about science, skepticism, feminism, and techno-futurism here at This Week In Tomorrow.
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