WASHINGTON — Elon Musk took to Twitter to remind Jeff Bezos — not to mention the SpaceX founder’s 2.9 million Twitter followers — that Blue Origin was not the first to vertically launch and land a reusable suborbital rocket.
“The rarest of beasts — a used rocket,” Bezos tweeted early Tuesday, the day after Blue Origin’s New Shepard successfully landed at its West Texas test site after launching to an altitude of 100.5 kilometers. “Controlled landing not easy, but done right, can look easy.” (The tweet itself is the rarest of beasts — the characteristically tight-lipped Amazon.com founder has only one tweet to his name, even though he joined Twitter in 2008).
Musk tweeted his congratulations but couldn’t resist quibbling with Bezos’ use of the word “rarest.”
— Elon Musk (@elonmusk) November 24, 2015
Musk followed up with another tweet reminding folks that SpaceX has been practicing vertical take offs and landings since 2012, albeit not to the same altitude New Shepard achieved Monday. SpaceX’s Grasshopper test rig — essentially a Falcon 9 first stage with a single Merlin engine —reached an altitude of 744 meters on its eighth and final flight. Its successor, the Falcon 9 Reusable Development Vehicle, safely landed after reaching 1,000 meters in a May 2014 test flight.
“Jeff maybe unaware SpaceX suborbital [vertical takeoff and landing] flight began 2013. Orbital water landing 2014. Orbital land landing next,” Musk tweeted.
Bezos on SpaceX
During a teleconference with reporters Tuesday, Bezos was asked about SpaceX’s efforts to field a partially reusable Falcon 9 rocket.”I would make three comments about some of the things that I’ve heard from SpaceX,” Bezos said. “One is that, you have to remember, SpaceX is only trying to recover their first stage booster, which is suborbital. So, of course, the first stage is suborbital.
“The second point that I would make is that the SpaceX first stage does an in-space deceleration burn to make their reentry environment more benign. So, if anything, the Blue Origin booster that we just flew and demonstrated may be the one that flies through the harsher reentry environment,” Bezos continued.
“And then finally, the hardest part of vertical landing and reusability is probably the final landing segment, which is the same for both boosters,” Bezos said.
Bezos’ and Musk’s entire (largely one-sided) Twitter conversation is reproduced here:
Congrats to Jeff Bezos and the BO team for achieving VTOL on their booster — Elon Musk (@elonmusk) November 24, 2015
Getting to space needs ~Mach 3, but GTO orbit requires ~Mach 30. The energy needed is the square, i.e. 9 units for space and 900 for orbit. — Elon Musk (@elonmusk) November 24, 2015