March 13, 2015 News

ESA re-entry vehicle could pave way for reusable launcher

Artist’s concept of the Intermediate Experimental Vehicle. Credit: ESA

European engineers are eager to test an experimental re-entry demonstrator Wednesday to validate technologies for future robotic exploration probes, winged space planes, and reusable rocket boosters.

The European Space Agency’s Intermediate Experimental Vehicle — about the size of a family car — will take off at 8 a.m. EST (1300 GMT) Wednesday aboard a Vega rocket from the Guiana Space Center on the northern coast of South America.

The launch window extends for an hour and 43 minutes for the 98-foot-tall Vega rocket to blast off and propel the IXV spaceship on a suborbital trajectory around the world, aiming for a precision parachute-assisted splashdown in the Pacific Ocean about 102 minutes later.

The mission passed a launch readiness review Monday, clearing the Vega launch team for final preparations for liftoff Wednesday.

“We have done the preparations for the IXV,” said Giorgio Tumino, EXA’s IXV program manager, in a phone interview from the launch site in Kourou, French Guiana. “Everything went smooth, and we are ready for the launch on the 11th. All our ground segment works perfectly, and our spacecraft is also ready. We do not expect any delay, apart from meteorological issues.”

Built by Thales Alenia Space of Italy, the European mini-shuttle weighs nearly 2 metric tons — about 4,000 pounds — and measures 5 meters long, or more than 16 feet. The IXV’s aerodynamic lifting body shape will help the craft steer its way to a landing point in the equatorial Pacific Ocean nearly 3,000 miles west of Colombia.

Tumino says the mission will help Europe perfect space systems that work from launch, through in-space operations, then return to Earth.

“Europe has leadership in going to orbit,” Tumino said. “We have the long history of the Ariane family up to the Ariane 5, and we have also the success of the new Vega launcher. We believe the European know-how in getting to orbit is quite good. We also believe that European competencies in operating advanced systems in space is among the best worldwide, with the ATV (space station supply ship) and the Rosetta mission (to comet 67P/Churyumov-Gerasimenko).

“We believe the return capability is running behind,” Tumino said. “We never closed the loop on the capability to go to orbit, operate in orbit and come back from orbit. The first objective of the IXV mission is we need to gain experience on these type of missions — the capability to return from orbit.”

The IXV mission has cost about 150 million euros — around $170 million — since its design phase started in 2002. The figure does not include the cost of the Vega launcher, which is paid from a separate ESA account.

A recovery team on the Italian Nos Aries vessel will pluck the IXV from the Pacific Ocean and return it to Europe for analysis.

“The mission will prove that in Europe we are able to master re-entry technologies,” said Roberto Provera, director of human spaceflight and transportation programs for Thales Alenia Space. “This is the first time in Europe we have flown a shape like this. It’s a lifting body, and at the moment in europe we don’t have this type of experience.”

Provera said the IXV mission is a “big step forward” for Europe.

“We dream of a space plane in the future,” Provera said. “It will take some time to develop, but I think with this flight we could make a move toward this path.”

The IXV’s flight is fully automated, but more than 300 sensors will record data on temperatures, pressures, loads, and other conditions throughout the flight.

The four-stage Vega launcher will boost the miniature shuttle to a speed just shy of the velocity required to reach Earth orbit, then deploy the payload about 18 minutes after liftoff.

The spacecraft will prime its 90-pound-thrust rocket thrusters, and coast to a peak altitude of 260 miles (420 kilometers), passing over ground stations in Gabon and Kenya staffed with engineers monitoring the flight.

“The vehicle has a pre-programmed landing site, so it will be heading toward the landing site after the separation from the Vega launcher, independently from where the Vega launcher will separate it,” Tumino said. “It will be heading toward the landing spot, and what it will do is after separation it will activate the subsystems. We have to perform priming operations in orbit, then prepare the vehicle itself to meet the atmosphere at 120 kilometers (74 miles).”

The spaceship will drop back into the atmosphere about an hour after launch, initially using thrusters to steer toward the landing site in the Pacific Ocean. Once the IXV reaches the lower atmosphere, where air offers more aerodynamic resistance, it will activate two rear-mounted flags to control the craft’s roll, pitch and yaw.

The IXV’s thrusters and electromechanical actuator components for the craft’s flaps were borrowed from the Ariane 5 and Vega launchers.

“We have built a lot on our launcher technology,” Tumino said. “It was very important because we could use this mission to help create reusable launcher technology.”

ESA director-general Jean-Jacques Dordain called the IXV mission a “key mission” as the space agency and contractors study the development of a reusable launcher. The Ariane 5 rocket’s replacement — the Ariane 6 — is an expendable design, but the following vehicle could have the capability to fly back to Earth for refurbishment and reuse.

Two ESA member states, Germany and France, have engineers studying the concept.

On the glide toward the splashdown site — located at approximately 3 degrees north latitude and 123 degrees west longitude — the IXV will perform a series of banking maneuvers to slow down, using inertial and GPS navigation to aim for the landing point.

The rolls are similar to maneuvers used by re-entering space shuttles to bleed off speed.

“It will need to do these banking maneuvers,” Tumino said. “It’s not that we do it for fun or the shuttle did it for fun. We need to go it to moderate the profile to stay within our own corridor. Every spacecraft has to navigate between two extremes. On one side is not to come in too steep, otherwise it burns up, and on the other side not to come in too shallow, otherwise it misses the target. So there is a need to moderate the lift and the drag in order to stay within these two boundaries, in order to truly fly while heading toward the landing point.”

The IXV will deploy a supersonic parachute made by U.S.-based Zodiac Aerospace, the same company which produced the parachutes for NASA’s Curiosity Mars rover landing system and the space shuttle’s drag chutes.

Splashdown in the Pacific Ocean is expected around 9:42 a.m. EST (1442 GMT) if the Vega rocket blasts off on time Wednesday.

A recovery team in the Pacific Ocean will purge the spacecraft of leftover toxic hydrazine and hoist it aboard the deck of the Nos Aries for a 40-day trek back to port in Genoa, Italy.

Engineers will inspect the spacecraft to evaluate how it performed during the flight. Data from the IXV’s sensor suite will also help analysts design future re-entry vehicles.

“There are a lot of new technolgoies that we will be flying on the IXV,” Provera said in an interview. “First of all, the thermal protection systems, both ceramic and ablative. We have an advanced guidance, navigation and control system. Besides just the technologies, I think one of the major points is to merge all the technologies all together into one flight vehicle. This is the real challenge for us as the prime contractor — to build a flight vehicle made of all-new technologies for Europe.”

ESA member states approved a follow-on space plane program called PRIDE, or the Program for Reusable In-orbit Demonstrator for Europe, that could launch by the end of the decade.

PRIDE will be about the same size as the IXV, but will enter orbit and return to Earth with a touchdown on land, perhaps on a runway. European officials say it is a smaller, civilian-run counterpart to the U.S. military’s X-37B space plane.

“I think there are many other technologies to prove before going for an operational system, such as orbital maneuver capabilities, precise landing, and so on,” Provera said. “I think PRIDE will be another step on this path, and hopefully we will have it flying in three or four years, so the lessons learned from IXV will not be lost.”

Follow Stephen Clark on Twitter: @StephenClark1.

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