How the holy grail of spaceflight could soon become reality

Long-time spaceflight the dream could soon come back in full force.

This month, Washington-based Radian Aerospace announced it was building a single-stage orbiting spaceplane that takes off and lands horizontally. The revelation sparked excitement for what could be considered the holy grail of the decades-old industry.

Christie Maddock, a lecturer in mechanical and aerospace engineering at the University of Strathclyde, says the “seductive concept” has been around for almost a century.

“Radian Aerospace’s announcement is exciting, primarily in that it signifies that work in this area, towards this goal, is underway,” Maddock said. Reverse. “What exactly this work is, and how successful it can be, is impossible to say without knowing the technical details.”

If Radian can pull it off, it could mean rockets that work more like planes. That means better reuse, faster reuse, and in Radian’s case, the ability to land on a wide variety of tracks.

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Here’s what you need to know about the technology:

Single-stage in orbit: why do we have stages?

First, a quick introduction. Space rockets do not fire their engines and head straight to their destination like a car: they are actually made up of several mini-rockets that fall off after use.

everyday astronaut note that the German Rocket V2 was the first to go into space, when in 1944 he reached an altitude of 109 miles. This placed it beyond the 62-mile Kármán line, generally accepted as the limit of space.

A replica of a V2 alliance/photo alliance/Getty Images

It’s fine for a short demonstration, but the rockets have to go faster to reach orbit. The goal is to break away from Earth’s gravity. The speed at which an object can escape Earth’s gravitational forces is its escape velocity, and for Earth it is approximately 25,000mph.

The problem with reaching this speed is that the rockets are heavy. More fuel gives more power, but it makes the rocket heavier. You find yourself in a game of cat and mouse trying to add enough fuel to power your increasingly heavy rocket.

That of the Soviet Union R-7 rocket family, which sent the first satellite into space, circumvented this problem by discarding engines and fuel tanks after the fuel ran out. The rocket would then use another smaller set of engines and fuel tanks to continue climbing.

“Same thrust, lighter mass, means higher acceleration,” says Maddock.

This process of losing weight, known as “staging,” fuels the space industry as it stands today. NASA’s Saturn V, which sent the first humans to the Moon, used three stages. SpaceX’s Falcon 9 uses two stages.

Saturn V from NASA.Congressional Quarterly/CQ-Roll Call, Inc./Getty Images

What is single-stage orbiting?

The problem with staging is that you dump components at launch time. This makes it more difficult to reuse a rocket.

SpaceX has focused on making the first stage of its fully reusable Falcon 9 rocket, but the second stage is still expendable. SpaceX CEO Elon Musk has pointed to airplanes as an ideal for why spaceflight companies should reuse rockets — it would be unreasonable to crash the plane or lose components on every flight.

“It’s really crazy that we build these fancy rockets and smash them every time they fly,” Musk said in 2017. SpaceX is currently developing a fully reusable spacecraft, where the booster and the craft land every two safely.

Airplanes, in a sense, are the ultimate example of why a single stage in orbit would be ideal – more durable, cheaper, less manufacturing involved.

Radian wants to use a concept known as a rocket sled launch, which starts horizontally, descending a track to gain speed before pulling up a ramp at the end, starting the rocket at an angle as it lifts off in opposition to a vertical launch that gradually rounds its trajectory to reach orbit.

How to make a single-stage rocket into orbit?

Maddock explains that there are a few techniques that researchers have explored:

  • Lifting surfaces as wings could help generate lift and reduce the need for more propellant – assuming the mass of the wings is less than the mass of the propellant
  • Use of air from the atmosphere as part of the propulsion system, replacing the oxidizer used in a propulsion system. Unfortunately, it would still have to revert to a more traditional rocket engine as the vehicle moved through the thinner atmosphere at higher altitudes.
  • The use of lighter materials make the mass smaller

What does Radian Aerospace promise?

We know little so far, but Radian is making big promises with the Radian One vehicle:

  • A rocket that take off horizontally with sleigh assistance
  • A comfortable ascent with lesser forces against the crew
  • Soft landings on any 10,000 foot runway
  • The ability to land and fly again in just 48 hours

Radian plans to use it to send crew and light cargo to low Earth orbit. It claims to have already entered into launch service agreements with “commercial space stations, in-space manufacturers, satellite and cargo companies”, as well as US and foreign governments.

In its latest reveal, Radian announced that it has closed $27.5 million in seed funding. Its advisory team includes Michael López-Alegría, who will fly as one of the first crew members on Axiom Space’s Ax-1 mission in late March.

Who else has tried to do a single-stage orbit?

Radian isn’t the first to consider a luge. Maddock notes that in 1933 Eugen Sänger unveiled the plans for the Silbervogel. This would have used a Radian-type rocket sled to accelerate the vehicle to 1,200 mph using a series of V2 rockets.

Jalopnik reports that the idea was dropped by the German government, but the US Air Force has explored a similar idea. Boeing’s X-20 Dyna-Soar replaced the V2s with Titan IIIs, but that too was discontinued in the 1960s. The concepts eventually helped build NASA’s multi-stage space shuttle.

In the 1986 State of the Union Address, President Ronald Reagan expressed his support for a new single-stage project in orbit:

“We are continuing our research into a new Orient Express that could, by the end of the next decade, take off from Dulles Airport, accelerate up to 25 times the speed of sound, reach low Earth orbit or fly to Tokyo in two hours.”

The National Aero-Space Plane, a NASA project, promised to reach orbit from virtually any airport. the New York Times reports that it promised to reach speeds of up to 17,000 mph and circle the globe in 90 minutes.

Unfortunately, the technical obstacles proved to be too many. In 1994, after spending $1.6 billion, the project was canceled.

Also in the 1980s, Rolls-Royce and British Aerospace explored the HOTEL space vehicle. This vehicle, with the acronym HOrizontal TakeOff and Landing, promised to travel from the United Kingdom to Australia in about an hour. It would have carried 15,400 pounds into low Earth orbit.

Whether Radian can succeed where others have failed remains to be seen.


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