Responding to demand for more cost-effective choices in the market for launching geostationary-orbiting satellites, International Launch Services (ILS) is introducing two lighter variants of the Russian Proton rocket to be available starting in 2018.

Both new variants will use the same basic hardware – including engines, fuel tanks and avionics – as the standard three-stage Proton Breeze M vehicle, a heavy-lift workhorse whose legacy dates back some 50 years. But there is one less stage in the planned Proton Medium and Proton Light rockets, yielding lower-cost alternatives in a market that in recent years has shifted toward lighter-weight satellites.

“Our customers have been asking for more tailored solutions and we’re responding,” ILS President Kirk Pysher explained. “The launch marketplace continues to be dynamic, and thanks in large part to our Russian-industry partners we’re able to quickly adapt.”

ILS will continue to market the Proton Breeze M, built by Khrunichev State Research and Production Space Center of Moscow, at least until 2020, ILS officials say. That rocket is capable of launching payloads weighing up to 6.3 metric tons to geostationary transfer orbit, which is where most commercial communications satellites separate from their launch vehicle en route to geostationary orbit 36,000 kilometers above the equator.

The Proton Light and Proton Medium vehicles will be capable of launching payloads weighing between 3 and 5 metric tons, to geostationary transfer orbit, ILS officials said. Proton Medium is expected to debut in 2018, with the smaller vehicle to follow in 2019.

Proton Medium and Proton Light give ILS a more competitive offering for satellites weighing 5 metric tons or less, which now make up more than half the commercial market. This shift has been driven in part by the introduction of electric propulsion systems that reduce – and in some cases eliminate – the need for the dense chemical propellant that satellites have traditionally used to fuel their climb to their final geostationary orbit.

ILS’s main competitors are Arianespace of Europe, whose Ariane 5 rocket is designed to launch two geostationary satellites at a time, one large and one relatively small; and SpaceX’s Falcon 9, which has established itself as the market’s low-cost option but recently was grounded following a launch pad accident. SpaceX has also sold commercial launches aboard its Falcon Heavy vehicle, which has yet to make its first flight.

On its website, SpaceX – a relative newcomer to the market – advertises an 8.3-metric-ton Falcon 9 lift capability to geostationary transfer orbit. But the commercial telecom satellites launched on the rocket to date have, with one exception, weighed less than 5 metric tons, and this is the market ILS is addressing with the new Proton Variants.

Industry officials say Falcon 9’s availability has nudged satellite operators and manufacturers toward the 5-ton weight class, which is less than ideal for both the Ariane 5 and standard heavy-lift Proton.

Proton Medium is effectively sharpening ILS’s competitive edge in this growing market niche, whereas the Proton Light likely will compete for satellites that otherwise would launch on Falcon 9 or in the Ariane 5’s lower berth, which is reserved for the smaller satellite in paired missions.

The Falcon 9’s near-term availability, meanwhile, is now in question following a Sept. 1 launch pad explosion that destroyed the vehicle, which was being fueled in preparation for a launch rehearsal, and its payload, a telecommunications satellite owned by Spacecom of Israel.

The new Proton variants eliminate the second stage of the existing Proton and partially offset the resulting power reduction by stretching out the first and third stages, which are then stacked together. Like the existing vehicle, the Proton Medium has six first-stage strap on boosters, while the Proton-Light has four.

“No test flights are planned of the new vehicles because of the proven reliability of their building-block components,” said Jim Kramer, ILS vice president of engineering and mission assurance. “Over the past 50 plus years, the Proton vehicle has flight proven experience in launching in a wide variety of configurations and conditions.”

Also like the standard Proton Breeze M, the Proton Medium and Proton Light will come with a 4-meter fairing, ILS officials said.

Though primarily focused on the geostationary market, ILS also is marketing the new Khrunichev-built Angara 1.2 vehicle with an advertised capability to launch up to 3 metric tons to low Earth orbit. ILS recently announced its first Angara 1.2 contract, to launch a radar imaging satellite for the Korean Aerospace Research Institute around 2020.

This post was produced by ILS and is being presented on as partner content.