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Europe to launch pioneering space plane

Anatoly Zak, Spaceflight Correspondent
Feb 7, 2015, 18:59 UTC

Sen—After an almost three-month delay due to a safety problem, European engineers are finishing preparations for liftoff of an innovative space glider on Feb. 11.

A wedge-shaped unmanned IXV vehicle will ride into space on top of a light-weight Vega rocket from the European Space Agency’s launch site in Kourou, French Guiana, on the Atlantic coast of South America.

After separation from Vega’s fourth stage at an altitude of 320 km, an experimental spacecraft will climb for another 100 km before starting its descent back to Earth. Zooming down with a speed of 7.5 km per second (the velocity of a typical orbiting spacecraft), the IXV will encounter a discernable atmosphere at an altitude of 120 km.

At this point, the real test for the IXV space plane will begin, as it attempts to use its exotic aerodynamic shape to slow down from its enormous speed to a soft splashdown under a parachute around 100 minutes after liftoff. A recovery vessel will be on hand in the Pacific Ocean to fish out the vehicle for the post-flight analysis of the daring mission.

The launch of IXV was originally planned for Nov. 18, however an unexpected safety issue stalled preparations around Oct. 24. As it turned out, in the unlikely event of veering off course during its first eastbound flight from Kourou, the Vega rocket could crash in populated areas on the coast of French Guiana.

“Of course in a nominal path, we don’t go over any populated area, but when you do a safety analysis, you have to take into the account 360° of all potential off-nominal cases and you have to preserve the compliance with all the safety measures,” says Giorgio Tumino, the manager of the IXV project.

By Nov. 21, the problem was resolved by re-programming Vega to make an initial ascent along its more routine northbound path, followed by a quick return to a prescribed trajectory across the Atlantic, along the Equator. Fortunately, the rocket had enough extra lifting capability to make this energy-hungry move, known as "dog-leg maneuver," with a two-ton IXV space plane.

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The new IXV space plane. Image credit: ESA

The IXV, or Intermediate eXperimental Vehicle, belongs to a very rare class of flying machines known as “lifting bodies” that rely on fuselage rather than wings to achieve an aerodynamic lift.

For spacecraft designers, the lifting body provides a compromise between a more maneuverable winged vehicle, which requires complex, heavy and failure-prone heat shield to protect its wings during a fiery reentry, and a capsule, which gives very little maneuverability.

According to Tumino, the IXV glider has a capability to veer as far as 400 km either to the right or to the left from its straight-line descent trajectory.

By most accounts, the IXV mission will be the world’s first attempt to return a pure lifting body from space. (In the past, the US and the USSR flew various experimental gliders with lifting body designs either at lower speed and altitude or augmented with some rudimentary wings.)

European engineers bank on the low-cost IXV project to catch up with the most advanced space powers like the US and Russia in the sophisticated field of atmospheric reentry technology. However the IXV project is undertaken not for a benefit of the particular future spacecraft but rather aims to give the European Space Agency, ESA, a broad experience, which could have a variety of future applications.

Tumino singled out such missions as the return of soil samples from other planetary bodies back to Earth, refueling and servicing satellites in orbit or even clearing space junk from busy orbital routes with the help of a reusable garbage truck. 

The future European space plane could also be used for sensitive microgravity experiments delivering alloys and chemicals produced in weightlessness back to Earth or for carrying scientific sensors into the stratosphere within a range of altitudes too high for an aircraft but too low for satellites.

Unfortunately, the European space budget does not currently provide for the development of the manned spacecraft, which would be the most obvious beneficiary of such a technology. Tumino also categorically denied any plans for military use of the project, due to strictly civilian nature of all ESA’s programs.

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An artist's impression of the IXV space plane working at a satellite in orbit. Image credit: ESA

With the recently approved funding, the IXV team hopes to build a follow-on returnable vehicle known as PRIDE, which stands for Programme for Reusable In-orbit Demonstrator for Europe. Unlike its purely experimental predecessor, PRIDE will have at least one practical job to do in the Earth orbit, Tumino explains.

“With respect to what to do in orbit, we will start after the IXV (flight) brainstorming in Europe and, potentially (in cooperation) with international partners, to define the objective and the mission for the PRIDE spacecraft.

Tumino named US, Russia and Japan as potential partners in the project. He reminded that early hopes to involve Russian specialists into the IXV project had never materialized. “The mission ultimately chosen for the vehicle, will determine its shape,” Tumino says.

Contrary to popular depictions of the PRIDE vehicle as a winged mini-Shuttle, Tumino hinted that a wingless lifting body chosen for the IXV project is currently seen as a favorite. “In the end, you use the wings in last four minutes of your flight just to do a runway landing, but you can also do a runway landing without wings, so it is not necessarily true that we will go for a winged vehicle,” Tumino said.

“We have to land on the ground, preferably on the runway, but, if in the end, we can land on grass to avoid wings and rudders, we could use a parafoil. So, all the design choices for the PRIDE are open,” Tumino added. 

What is certain is that PRIDE will again rely on the light-weight and low-cost Vega booster, keeping its mass and size roughly within the parameters of the IXV space plane: 2 tons, 5 x 2.2 x 1.5 meters. All key specifications and the mission for the PRIDE space plane should be determined during initial stages of the project known as Phase A and B. They are to be completed before the end of next year, clearing the way to a full-scale development in 2017.

If everything goes as planned, (which it rarely does in such complex and innovative projects), the PRIDE could debut in 2020.