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Why you shouldn't compare Blue Origin's rocket landing to SpaceX

Why you shouldn't compare Blue Origin's rocket landing to SpaceX

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For the past year, SpaceX has been trying to gently land its Falcon 9 rocket after launching it into space. The goal is for a large portion of the Falcon 9 to touchdown on a floating barge at sea post-launch, but the two times SpaceX has tried it after a return from space, the rocket was unable to stick the landing. A recovery of the rocket would be a major step toward making a fully reusable rocket — something that’s never been done before.

Then this morning, Jeff Bezos-backed spaceflight company Blue Origin blindsided everyone. The company revealed it had accomplished a rocket landing of its own. After launching the New Shepard rocket to the edge of space, the vehicle gently touched down on the ground at Blue Origin’s test facility.

Is it fair to compare the two companies? Not exactly

The feat was immediately compared to what SpaceX has been trying to do all year. It seemed that Bezos had beaten Musk in the race to reusability. SpaceX has had successful tests of its rocket’s landing capabilities, although those test flights didn’t go into space first. Still, the comparison struck a nerve with Musk, who issued a few tweets downplaying the historicalness of the event.

Musk has a point, though. Is it fair to compare the two companies and the types of landings they're trying to achieve for their vehicles? Not exactly.

SpaceX versus Blue Origin

The New Shepard and the Falcon 9 have very different designs, which stem from their very different mission goals. SpaceX's Falcon 9 rocket is meant to launch payloads — such as satellites and cargo — into orbit around Earth and beyond. It's why the rocket's shape is so thin and tall; it creates less drag on the vehicle, allowing it to break free from the atmosphere more easily and go deeper into space. But such a shape also makes it much harder for the rocket to land upright back on Earth. The engines on the bottom of the rocket help to orient it vertically during descent, but it's almost like dropping a lead pipe from the roof and having it land on its end. The rocket is prone to tilt and fall over.

The New Shepard and the Falcon 9 have very different designs

The New Shepard isn't meant to go as far up as the Falcon 9, however, which is echoed in the rocket's shape. The vehicle is only designed to take people to sub-orbital space for about four minutes. An object at this height isn't going fast enough to make a full rotation around Earth, so it hasn't quite broken free of the bonds of the planet's gravity and will eventually be pulled back down to the surface. Because New Shepard doesn't need go to the same heights as the Falcon 9, its shape doesn't need to be as tall and thin. Blue Origin's rocket sports a thicker and shorter structure, making it a tad easier to land vertically — albeit a still challenging task.

To be fair, the part of the Falcon 9 that SpaceX is trying to recover doesn't actually reach orbit, either. The company is only looking to land the first stage of the vehicle — the long rocket body that houses the main engines and most of the fuel. This section breaks apart from the rest of the rocket in sub-orbital space before falling back to Earth. Yet it reaches an ultimate height of 124 miles, twice the height of the 62-mile height at which New Shepard starts falling. And since the Falcon 9's ultimate goal is to achieve orbit, the first stage is traveling at a much greater speed than New Shepard when it begins its descent to the ground. New Shepard reaches a maximum velocity of Mach 3 during its trip, whereas the Falcon 9's first stage reaches between Mach 5.5 and Mach 7.5 before falling.

The Falcon 9 also has a lot more thrust and energy behind it when it's going into space, too. A whopping 1.5 million pounds of thrust lift the vehicle off the ground, compared to the maximum thrust of 100,000 pounds that New Shepard achieves. That means the Falcon 9 has a lot more force behind it as it starts its final descent. If these differences weren't enough, the Falcon 9 is also oriented completely different at the time of descent. It's at a horizontal configuration compared to Earth, meaning the company must do a complicated flip maneuver to get the Falcon 9 in position for landing. The New Shepard remains mostly vertical for the entirety of its flight.

Overall, comparing sub-orbital spaceflight to orbital spaceflight is pretty controversial. It's almost like comparing mountain climbing at the gym with climbing Mount Denali. The types of landing techniques involved can hardly be viewed on the same playing field, since New Shepard and Falcon 9 are drastically different vehicles.

Comparing sub-orbital spaceflight to orbital spaceflight is pretty controversial

"Blue Origin has designed their rocket to be reusable from day one. Elon is trying to take the first stage of his rocket, which was expendable, make some tweaks to it, and then make it reusable," said Charles Miller, president of NexGen Space LLC. "These are very interesting differences between how Musk and Bezos are approaching their rockets."

A first? Depends on your definition

Blue Origin's achievement has been lauded as the first landing of a commercial sub-orbital rocket, but it's only a "first" depending how you actually define the word "rocket." These days, the term is typically used to describe the cylindrical, vertical take-off vehicles that transport objects into space — like the Falcon 9 or the United Launch Alliance's Atlas V. If that's how you use the term rocket, then yes, this is the first time a rocket has reached sub-orbital space and then landed vertically on the ground afterward.

It's only a "first" depending how you actually define the word "rocket"

However, "rocket" has been used to describe any vehicle with a rocket engine. If that's your definition, then Blue Origin isn't the first commercial company to build and successfully test a reusable sub-orbital rocket. Scaled Composites had them beat on that with its SpaceShipOne spaceplane, which won the Ansari X Prize in 2004. That vehicle didn't launch vertically, though. It was transported to a high altitude by a carrier aircraft, where it then launched into sub-orbital space.

Predating them all is the North American X-15, an experimental rocket-powered aircraft used by the US Air Force in the 1960s. Like SpaceShipTwo, the X-15 was also designed to be carried to a predetermined height and then launch into sub-orbital space, which it did twice.

Regardless of what the word rocket means to you, Blue Origin's achievement is still impressive. Landing a rocket vertically after it reaches the edges of space is an incredible challenge that no one has quite mastered before. The feat belongs in the record books, though it's unclear the exact record that Blue Origin now holds.

Update November 25th 8:40 am: The article was updated to clarify what constitutes sub-orbital spaceflight.

Correction: SpaceShipOne is one of the few commercial vehicles to have made the trip to sub-orbital space, not SpaceShipTwo.