A Russian Soyuz rocket launched from the Vostochny Cosmodrome at 3:57 p.m. EDT (1957 GMT) Saturday with three Gonets data relay payloads and a demonstrator spacecraft for a proposed constellation of Russian broadband internet satellites.
The three-stage Soyuz-2.1b rocket, topped by a Fregat upper stage, took off at 4:57 a.m. local time from Vostochny, Russia’s newest spaceport near the country’s border with China in the far eastern Amur Oblast. The rocket shed its first stage boosters about two minutes after liftoff, then jettisoned its payload fairing and core stage. A third stage engine fired several minutes before releasing the Fregat upper stage to begin maneuvers before deploying the four satellite payloads.
The Soyuz headed north from the remote spaceport to target a near-polar orbit, using its Fregat upper stage to place the three Gonets-M data relay satellites into an orbit about 932 miles (1,500 kilometers) above Earth.
The three 617-pound (280-kilogram) Gonets-M satellites will separate first from the Fregat upper stage, which will then reignite multiple times to inject Russia’s 352-pound (160-kilogram) Skif-D tech demo satellite into a much higher orbit about 5,014 miles (8,070 kilometers) above Earth. The entire launch sequence will take about four hours from liftoff until separation of the final satellite.
Russian government ministries and civilian authorities use the Gonets-M satellites to relay secure messages between mobile terminals and fixed operators.
The Gonets fleet is effective in Russia’s far northern regions out of reach of conventional satellite communications systems. Messages relayed by the Gonets network are transmitted from the ground to a satellite passing overhead, then stored in the craft’s memory until it flies over the message’s recipient.
The payloads launched Saturday are designated Gonets-M satellites No. 33, No. 34 and No. 35. The Gonets system is operated by a public-private partnership between Roscosmos — the Russian space agency — and Russian industry.
Gonets means “messenger” in Russian.
According to ISS Reshetnev, the manufacturer of the Gonets satellites, the network is used for tracking cargo and vehicles, monitoring industrial activity, provides communications in remote areas, supports emergency responders, and helps in other global corporate and government data transmission networks.
The Skif-D satellite is the first spacecraft to launch for Russia’s Sphere constellation, a program established by the Russian government in 2018 to provide broadband internet connectivity, message relay capability, video broadcasts, and remote sensing services. The Sphere constellation is envisioned to consist of 162 satellites.
Skif-D, built by ISS Reshetnev like Gonets satellites, will demonstrate technology for one component of the Sphere constellation, called Skif, that is designed to operate at a medium-altitude orbit to transmit and receive high-speed internet signals.
The launch Saturday marked the first time a Soyuz rocket has been entirely fueled with naphthyl, a hydrocarbon similar to the kerosene fuel previously fed into Soyuz engines. Russia’s space agency says the naphthyl fuel is an environmentally safe type of hydrocarbon fuel. The naphthyl fuel also slightly improves the Soyuz rocket’s engine performance, allowing it to haul heavier cargo into orbit.
“The quality indicators, physical and chemical properties and operational characteristics of the hydrocarbon fuel naphthyl are close to those of kerosene,” said Progress Rocket Space Center in Samara, Russia, the manufacturer of Russia’s Soyuz rocket family.
The switch in fuel type did not require any significant changes to the Soyuz engines, since there are only minor differences in thermal properties, viscosity, and surface tension between kerosene and naphthyl. Naphthyl has fewer aromatic compounds than kerosene, according to the Soyuz rocket contractor.
The change required ground testing of Soyuz engines to ensure they would handle the new fuel type. Naphtyl fuel was previously flown only on the Soyuz third stage, but the launch Saturday was the first time the first and second stage engines also burned the new fuel.
Saturday’s mission was the 15th flight of a Russian Soyuz rocket this year, and the 1,968th launch of a rocket in the Soyuz family since the 1950s.
Email the author.
Follow Stephen Clark on Twitter: @StephenClark1.