PARIS — Europe’s heavy-lift Ariane 5 rocket will be unable to launch any commercial missions for the next six months because of worsening payload compatibility issues that Ariane 5 designers hope to solve with the vehicle’s planned upgrade.

But that modification, called Ariane 5 Midlife Evolution (ME), will not make its first flight before 2016 at the earliest and will not be in regular service before 2018 — and then only if European governments approve the program’s remaining development budget, estimated at about 1.5 billion euros ($2 billion).

Following an agreement between France and Germany on Ariane 5 ME, the 19-nation European Space Agency (ESA) is expected to approve the program during a conference in late 2012.

For the next seven years then, Europe’s Arianespace commercial launch consortium will have to cope with the gradually increasing weight of the average telecommunications satellite by matching payloads as best it can while staying within Ariane 5’s current limits.

Sometimes it cannot, as is the case now. The Sept. 21 launch of an Ariane 5 rocket carrying the vehicle’s customary two telecommunications satellites will be the vehicle’s last in 2011. An annual mission count of just five launches will make it difficult for Evry, France-based Arianespace to turn a profit. The company has posted small losses in each of the past two years despite the continued reliability of Ariane 5, whose Sept. 21 launch was its 46th consecutive success.

The Ariane 5 vehicle’s business model depends on carrying two commercial customers at a time into geostationary transfer orbit. The model was developed for the previous Ariane 4 vehicle and perfected in the 1990s.

Ariane’s main competitors, then and now, focus on delivering one heavy satellite into orbit per launch. Rare are the commercial satellites that are so large they cannot fit onto the International Launch Services Russian-built Proton rocket, operated from Russia’s Baikonur Cosmodrome in Kazakhstan; or the Sea Launch vehicle, operated from the Pacific Ocean by a Russian-based consortium.

The Ariane 5 rocket’s record for satellite weight was set in April, when the rocket lifted two satellites weighing a combined 8,956 kilograms into geostationary transfer orbit. The structure used to keep the satellites stable and separated during the ride through the atmosphere, plus other adaptors, put the entire weight carried into orbit at 10,050 kilograms.

In the past several years, heavy commercial telecommunications satellites have grown heavier. Many weigh 6,000 kilograms today. Even the lighter satellites have put on weight, with many reaching 3,000 kilograms once filled with fuel and ready for launch.

While Ariane 5 prime contractor Astrium Space Transportation and its subcontractors continue to make strides with incremental improvements in the vehicle’s performance, it is typically a matter of several kilograms here and there, no more.

Arianespace today offers a maximum of 9,300 kilograms of combined payload capacity aboard the Ariane 5. Keeping within that limit for two satellites involves occasionally sophisticated planning, months in advance, when satellite launches are booked. Some customers are in more of a hurry than others. What if one is late? The latest satellite operator to find that out is Sky Perfect JSat Corp. of Tokyo, a big customer for Arianespace. The company’s JCSat-13 satellite, which when ordered from Lockheed Martin Space Systems in 2009 was aiming for a flight in 2013, is ready for a launch now.

Sky Perfect JSat announced that it would fly on an Ariane 5 rocket in late 2011. The satellite is expected to weigh about 4,500 kilograms at launch — a midrange satellite for which Arianespace needed to find a co-passenger weighing 4,800 kilograms or less.

Several potential candidates came and went, either because their owners decided on other vehicles or because the satellites would not be ready in time.

On Aug. 3, Sky Perfect JSat announced that its 2011 launch was scrapped, and that JCSat-13 would not be launched by Arianespace before April “due to the launch service provider’s reasons.”

The launch schedule problem has been exacerbated by the fact that ESA’s ATV-3 unmanned space station cargo carrier had previously booked a late-February or early-March flight aboard an Ariane 5. Arianespace has ruffled European government feathers in the past by appearing to move ESA missions around to favor commercial customers, and there was no question of doing that this time around.

The current ATV-3 launch dates are Feb. 29 or March 7.

It is still unclear whether the arrival of Russia’s medium-lift Soyuz rocket at Europe’s Guiana Space Center spaceport will affect Ariane 5’s business. While intended mainly for European government satellites, the Soyuz variant to be used next-door to Ariane 5 is able to launch a 3,000-kilogram telecommunications satellite into geostationary transfer orbit and could nibble at the edges of the Ariane 5 market.

At the Space Access conference here Sept. 21-23 organized by Astech Paris Region, officials from ESA, Astrium Space Transportation and the French space agency, CNES, outlined the status of the Ariane 5 ME program.

The current performance target, they said, is 11,300 kilograms into geostationary transfer orbit. Subtracting the adaptors and the Sylda structure to separate the satellites means two satellites weighing a combined 10,500 kilograms could be launched by the Ariane 5 ME vehicle now planned for 2018. Program managers said they expect the vehicle’s performance to rise to 10,700 kilograms.

ESA, CNES and Astrium designers appear to have reached a consensus that the successor to Ariane 5 will be a modular rocket designed to carry satellites weighing between 3,000 and 8,000 kilograms into geostationary transfer orbit — one at a time.



Arianespace is Rethinking its Dual-Launch Strategy

Le Gall Makes Appeal for Starting Ariane 5 Successor

ESA Putting Arianespace Finances Under the Microscope

Peter B. de Selding was the Paris bureau chief for SpaceNews.