TORONTO — The Japan Aerospace Exploration Agency on Sept. 29 said that for the next launch of its new Epsilon small-satellite rocket, its upper stage will be discarded in an orbit low enough to re-enter Earth’s atmosphere in keeping with international debris-mitigation guidelines, avoiding the problem following the vehicle’s September 2013 inaugural flight.
Epsilon’s first flight, which was a success, left two large objects — the rocket’s upper stage and a smaller post-boost stage — in an orbit with a perigee of some 800 kilometers, meaning neither will fall into the atmosphere for a century or longer. In the meantime, they will add to the population of orbiting garbage that poses a threat to active satellites traversing this orbit.
Japan is an active member of the Inter-Agency Space Debris Coordination Committee, a grouping of most nations that conduct space launches that sets guidelines on debris mitigation. One of those guidelines is that rocket bodies and satellites in low Earth orbit be removed from orbital highways through retirement at altitudes that will force their re-entry within 25 years.
Addressing the 65th International Astronautical Congress here, Epsilon Program Manager Yasuhiro Morita of JAXA said Epsilon’s next launch, set to occur in late 2015 or early 2016, will end with Epsilon components being sent into an orbit that will assure their re-entry.
“We’ll deorbit it so that it does not produce debris,” Morita said. It was unclear whether the deorbit maneuver — using rocket fuel to propel the upper stage into a lower-perigee orbit — would be done systematically or would depend on the fuel requirements and orbit of each individual Epsilon mission.
JAXA and IHI Aerospace Ltd., which builds Epsilon components that are then integrated by JAXA, have high hopes for the vehicle on the global commercial market. Operators of small satellites intended for low Earth orbit routinely complain of the lack of affordable launch options.
The current Epsilon configuration can place a satellite weighing 1,200 kilograms into a low Earth orbit and a 450-kilogram satellite into a sun-synchronous orbit. Its solid-fueled stages borrow heavily from Japan’s H-2A heavy-lift vehicle, and JAXA is designing an upgraded Epsilon to increase payload mass and to reduce costs.
Morita said the Japanese government is likely to use Epsilon enough to assure one launch per year. That rate will have to be increased to generate substantial savings in vehicle cost. Morita said the goal is to reduce by 30 percent the vehicle’s cost of production, which for the inaugural flight a JAXA official said was around $50 million.
One of the particularities of Epsilon’s low-cost approach is its mobile launch-control center, which requires the presence of only a handful of people and can be transferred at little cost. “We could perform launch control from anywhere in the world,” Morita said.
The control center is located outside the 2-kilometer-radius high-security area of Japan’s Uchinoura Space Center, increasing safety and lowering security-related costs.
The enhanced Epsilon version will be introduced at least in part as soon as the second flight. Most of the modifications to increase power are in the vehicle’s second stage, which in the enhanced version will be longer.
Morita said Epsilon program managers are looking at what it would take to provide a dual-launch capability for the rocket to give it “better user-friendly characteristics” as IHI turns to marketing Epsilon services worldwide.
