Russian Proton-M lofts new geostationary weather satellite

by William Graham

Russia has launched a new geostationary weather satellite, Elektro-L No.3, on Tuesday aboard a Proton-M rocket which flew from the Baikonur Cosmodrome. Liftoff occurred on time at 18:03 local time (12:03 UTC), conducting a six-and-a-half-hour mission for Russia’s veteran heavy-lift rocket.

Elektro-L No.3 is the third in a series of weather satellites that Russia is deploying to geostationary orbit, from where the satellites can image and monitor the full disc of the Earth. The Elektro satellites complement Russia’s low-orbit Meteor satellites in returning data that meteorologists can use to build forecasts and study the climate.

From their vantage points high above the Earth’s equator, Elektro-L satellites monitor wide areas of the planet’s surface. Elektro-L No.3 will be positioned over the Pacific Ocean at a longitude of 165.8 degrees East. This will allow it to observe Russia’s far eastern regions, as well as Oceania and parts of Asia.

The satellite will join the Elektro-L No.1 and No.2 satellites in orbit. These were launched aboard Zenit-3F rockets in January 2011 and December 2015 and operate at longitudes of 14.5 and 77.8 degrees East respectively.

Weighing in at 2,094 kilograms (4,616 lb), Elektro-L No.3 is slightly heavier than its two predecessors. This is likely due to additional propellant – the Proton rocket that will launch No.3 is more powerful than the Zenit vehicles used to launch the last two satellites, which were launched with part-empty tanks to keep them within Zenit’s payload envelope. The additional propellant will allow Elektro-L No.3 to station-keep for longer, giving it a better chance of exceeding its planned ten-year design life.

The Elektro-L satellites were built by NPO Lavochkin and are based around the Navigator bus. Its primary instrument is the 106-kilogram (234-pound) Multispectral Scanner – Geostationary (MSU-GS), an imager operating at ten visible and infrared wavelengths which can image the full disc of the Earth twice per hour. It can produce visible-light images at resolutions of up to one kilometer (0.6 miles, 0.5 nautical miles), and infrared images at resolutions up to four kilometers (2.5 miles, 2.2 nautical miles).

Visible-light and midwave infrared observations will help monitor cloud cover and water vapor in the Earth’s atmosphere, while observations at thermal infrared wavelengths will be used to keep track of sea surface temperatures.

As well as terrestrial weather forecasting, Elektro-L satellites have a role in monitoring space weather which can affect the Earth. The satellite’s heliogeophysical instrument complex, GGAK-E, is a suite of sensors to study solar radiation, charged particles in the ionosphere and the Earth’s magnetic field. GGAK-E contains seven individual instruments.

The SKIF-6 and SKL-E spectrometers which will monitor electron and proton densities, while GALS-E is a cosmic ray detector. Three instruments will monitor radiation from the sun: ISP-2M will study the total irradiance, while VUSS-E and DIR-E will respectively monitor ultraviolet and x-ray radiation. The FM-E magnetometer will study the magnetic fields that the satellite passes through as it orbits the Earth.

Elektro-L also carries a communications payload. This serves two purposes: relaying data from remote research stations around Russia back to central ground stations and carrying emergency communications as part of the KOSPAS-SARSAT network.

Tuesday’s launch completes the initial Elektro-L constellation, giving Russia three satellites in orbit for global coverage. The next Elektro-L satellite is currently slated for launch in 2021 to replace Elektro-L No.1 as it reaches the end of its design life.

Tuesday’s launch used a four-stage Proton-M/DM-03 rocket. This consisted of the Proton-M carrier rocket and a Blok DM-03 upper stage, a powerful combination that allows Russia to place satellites directly into near-geostationary orbit from its high-latitude launch sites. The last two Elektro-L satellites rode Ukrainian-built Zenit rockets to orbit, however, political developments between Russia and Ukraine have led to a suspension of Zenit launches, necessitating the switch to Proton.

The rocket that performed Tuesday’s launch consisted of Proton-M number 93-566, coupled with Blok DM-03 No.3L. Proton was built by Russia’s Khrunichev State Research and Production Space Centre, Blok DM-03 was manufactured by RKK Energia.

This was the fifth flight of the Blok DM-03 upper stage, which was introduced in 2010 as an enlarged and upgraded version of the earlier Blok DM-2. The new stage’s first two launches failed – although in neither case because of a problem with the Blok DM-03 itself.

On the maiden flight in December 2010 the stage was fuelled according to protocols developed for the Blok DM-2, which resulted in too much propellant being loaded making the rocket too heavy to reach orbit. The second Blok DM-03 was launched in July 2013 but was lost seconds later when its Proton-M booster went out of control as soon as it left the launch pad. An incorrectly-installed sensor in the vehicle’s first stage was blamed for the failure. Both of these launches had been intended to deploy groups of three GLONASS navigation satellites.

Proton-M and Blok DM-03 achieved success at the third time of asking in September 2015, deploying the Ekspress AM-8 communications satellite, and followed this up with the successful launch of the Spektr-RG x-ray astronomy satellite earlier this year.

The rocket used two different combinations of liquid propellants. All three of the Proton-M stages burned storable hypergolic propellants: unsymmetrical dimethylhydrazine oxidized by dinitrogen tetroxide. Blok DM-03 was fuelled with RG-1 kerosene and liquid oxygen.

The Proton-M booster itself is a descendent of Vladimir Chelomei’s UR-500 missile, designed as part of his Universalnaya Raketa – Universal Rocket or UR – series. With UR, Chelomei proposed a set of rockets sharing common technologies and components to cover a full spectrum of classes of ballistic missile and satellite launcher. UR-500 was conceived as a two-stage intercontinental ballistic missile, capable of carrying the Soviet Union’s heaviest nuclear weapons. The vehicle proved too large to be a practical missile, however with the addition of a third and optional fourth stage, it proved a capable vehicle for delivering heavy satellites to low Earth orbit, or smaller spacecraft to higher orbits and interplanetary trajectories.

After the two-stage UR-500 had flown four times with physics research satellites in 1965 and 1966, the three-stage UR-500K was introduced. This version, soon renamed Proton-K, initially suffered from poor reliability but once these issues were resolved it became a capable and dependable workhorse. Proton-K remained in service until 2012.

Proton-M was developed as a modernized version of Proton-K, incorporating upgraded engines and a digital flight control system. It first flew in April 2001 and was phased in, first with commercial payloads and later military satellites. The rocket has undergone incremental “phase” upgrades, further increasing its performance and payload capacity. Depending on mission requirements, Proton-M can fly with a Briz-M or Blok DM-03 upper stage. The now-retired Blok DM-2 was previously flown on Proton-M, while next year’s planned launch of the International Space Station’s Nauka module will use a three-stage Proton-M with no upper stage.
From the late 1990s until the mid-2010s, Proton attracted significant interest for commercial launches of geostationary communications satellites, carried out by International Launch Services. Proton reached a relatively high launch rate in this period, but in later years it was plagued by quality control issues and launch failures: from February 2006 to May 2015, eleven out of 86 Proton launches failed to reach their planned orbits. Reliability concerns, coupled with increased competition, have reduced Proton’s share of the market. This has resulted in reduced launch rates, although the rocket has not failed since.

Proton lifted off from Pad 24 at Site 81 of the Baikonur Cosmodrome, in what may have been the last launch from this complex. Pad 24 would be due to enter a maintenance period in the next few months, but with Proton’s reduced flight rate and impending retirement, the pad is expected to be decommissioned instead. With the next Proton launch not scheduled to take place until March, it is unclear whether Pad 24 will still be available when this comes around.

The original Proton launch facility at Baikonur, Site 81 was built with two launch pads: Pads 23 and 24. Pad 23 was the venue for the maiden flight of the UR-500 – the original two-stage version of Proton – in July 1965, while Pad 24 came online in November 1967 with a Proton-K launch. Two additional launch pads were built at Site 200 in the 1970s, with Pad 40 entering service in July 1977 and Pad 39 in February 1980. With the retirement of Pad 24 – which is not yet confirmed – Site 200/39 will be the last operational Proton launch complex. Site 200/40 has not been used since 1991, while Site 81/23 left service in 2004.
Site 81 supported many historic launches under the Soviet space program, including probes to the Moon, Mars and Venus as well as space stations and prototypes for crewed spacecraft which never got to carry cosmonauts into orbit. Some of the earliest Proton-K launches from the site carried Soyuz 7K-L1 spacecraft, a stripped-down version of the Soyuz designed to fly around the Moon and return to Earth without entering Lunar orbit. A number of uncrewed test flights were conducted, with mixed results, however, Soyuz 7K-L1 never carried crew.

Late missions in the Luna program were also launched from Site 81 after the E-8 series spacecraft outgrew the Molniya rocket and made the switch to Proton. The Luna 17 and Luna 21 missions, which deployed Lunokhod rovers onto the Moon’s surface, both flew from pad 81/23, while an earlier failed launch was made from 81/24. E-8-5 spacecraft were launched from both pads on sample-return missions, with the successful Luna 16, 20 and 24 launching from pads 23, 24 and 23 respectively. Two orbiter missions, Lunas 19 and 22, lifted off from Pad 24.

Missions to Mars and Venus were flown from Site 81 in the 1970s. These followed on from a pair of failed launches in 1969 – one of which suffered an engine failure on departure from Pad 24 and flew at low level before impacting near the pad, about half a minute after liftoff. A similar failure, caused by an incorrectly-installed sensor, would occur at the same pad years later during the 2013 Proton-M/DM-03 GLONASS launch.

Following another failure in early May 1971, two probes were launched successfully later in the month as Mars 2 and 3 – using both pads to ensure a quick turnaround. Mars 3 became the first spacecraft to land on Mars six months later, however, it failed after about fifteen seconds on the surface. In late July and early August 1973, the two pads of Site 81 were used for a salvo of four launches to the Red Planet: the Mars 4 and 5 orbiters were launched four days apart. Eleven days later the Mars 6 lander lifted off from Pad 23, with another lander, Mars 7, flying from Pad 24 after another four days.

Four Venera missions to Venus – Veneras 9 and 10 in June 1975, and 11 and 12 in September 1978, also flew from Site 81. In the mid-1970s Site 81 was the scene of the Soviet Union’s first geostationary satellite launches: Kosmos 637, a mass simulator for the Raduga military communications satellite, was deployed to a near-geostationary orbit by a Proton-K rocket with a Blok DM upper stage, flying from Pad 23 in March 1974. Four months later, another Proton-K/DM lifted off from Pad 24 with the Molniya-1S No.38L communications satellite.

On 19 April 1971, a Proton-K rocket lifted off from Site 84/24 to deploy the world’s first space station, Salyut 1. The later Salyut 4 and Salyut 6 stations both launched from the same pad, while Salyuts 2, 3 and 5 – along with two more failed stations – flew from Pad 23. Pad 23 was also used for the launch of two modules of the Mir space station – Spektr and Priroda – and the Zarya and Zvezda modules of the International Space Station. Zarya, the first module of the ISS, was launched in November 1998.

When Site 200 came into service in the late 1970s, launches from Site 81 decreased except for a small number of TKS launches from Pad 24. TKS was designed for both crewed and uncrewed missions in support of Soviet military space stations, however, after several uncrewed test flights, the spacecraft was largely abandoned. Leftover hardware later formed the basis of several space station modules. After these few launches, Site 81 fell into disuse and from May 1979 until December 1989, no launches occurred from the complex.

Pad 23 was reactivated in 1989 and for the next six years supported Proton rockets with mostly military payloads bound for geostationary or Medium Earth orbit. In April 1996 it was the site of Proton’s first commercial launch under International Launch Services (ILS), which carried the Astra 1F satellite for SES Astra. Pad 24 remained inactive until July 1999 when it returned to service with upgrades to accommodate the then-new Briz-M upper stage. The first launch after refurbishment carried an obsolete Gran’ military communications satellite in a test of the Briz-M’s capabilities, however, failed because of a malfunction with the second stage of the carrier rocket. Briz-M flew successfully a year later and began to supplant the Blok-D and DM series upper stages for most Proton launches. Site 200/39 was later modified so it could also launch Protons with Briz-M upper stages.

Over the last fifteen years, Russia has mostly used Pad 81/24 for military and government launches and Pad 200/39 for commercial missions, however a handful of commercial launches have flown from Pad 24, and launches for the state-owned Russian Satellite Communications Company have used both pads. If Tuesday’s launch has marked the end of Site 81/24’s many years of service, Site 200/39 will take over all launch operations until Proton’s retirement – which is expected in the late 2020s.

Tuesday’s launch was the ninetieth to take place from Pad 24, and the 194th overall from Site 81.

As the countdown reached zero, Proton’s six RD-275 main engines roared to life propelling the rocket into the sky above Baikonur. Each first-stage engine is affixed to the bottom of a fuel tank, with the six tanks clustered around a central oxidizer tank. This unusual configuration was developed to make Proton easier to transport – as all components can travel by rail and are integrated when the rocket reaches the horizontal assembly building – or MIK – at the launch site.

The first stage burned for 123.8 seconds. Moments before burnout, Proton’s second stage engines ignited, and the two stages separated. This “fire-in-the-hole” stage separation simplified the startup of Proton’s second stage by using the rocket’s continuing acceleration to keep propellant settled in its tanks. By doing this Proton avoids needing to carry ullage motors for this purpose. A lattice interstage structure at the top of Proton’s first stage allowed exhaust gases to escape from the second stage engines prior to separation.

Proton’s second stage was powered by four engines: three RD-0210s and an RD-0211. The RD-0211 was a modified RD-0210, incorporating additional hardware to pressurize the stage’s propellant tanks, however, otherwise all four engines were identical. They burned for three minutes and 27.6 seconds as Proton continued the climb to orbit. At the end of this burn, Proton’s second and third stages separated from each other.

The third stage was powered by the RD-0212 propulsion system, consisting of two individual engines: and RD-0213 main engine and a four-chamber RD-0214 vernier engine which helps to control the rocket’s attitude. This burned for four minutes and 12.5 seconds, delivering Blok DM-03 and its payload to an initial suborbital trajectory. Shortly after third stage ignition, Proton’s payload fairing was jettisoned. The fairing, used to protect the rocket’s payload during ascent through the atmosphere, is not needed once the rocket reaches space and was therefore discarded to save weight.

Shortly after the end of its burn, Proton’s third stage was jettisoned. Blok DM-03 carried on alone with Elektro-L No.3, with three engine burns needed to reach a near-geostationary orbit. The first burn started six minutes after separation, establishing an initial 175.5 by 208.8 kilometer (109.1 by 129.7 mile, 94.8 by 112.7 nautical mile) parking orbit.
Seventy-two minutes and fifty-nine seconds after liftoff, Blok DM-03 relit its engine for the second burn, targeting a 251.8 by 35,487.4 kilometer (156.5 by 22,050.8 mile, 136 by 19,161.7 nautical mile) geostationary transfer orbit. After a lengthy coast phase as the upper stage and payload climb towards the highest point – or apogee – of their trajectory, DM-03 began its third and final burn at six hours, 25 minutes and 19 seconds mission elapsed time.

This circularized the orbit at 35,405.5 kilometers (22000.0 miles, 19,117.4 nautical miles) altitude – a few hundred kilometers below the geostationary belt. With the circularisation burn complete, Elektro-L No.3 separated from Blok DM-03 to begin its own mission.

Tuesday’s launch was the fifth and final Proton launch of 2019, following successful launches in May, July, August and October. May’s launch deployed the Yamal 601 communications satellite before July’s mission carried the Spektr-RG observatory into orbit. In August a military Blagovest communications satellite, Kosmos 2439, was launched before October’s commercial launch carried the Eutelsat 5 West B satellite and Northrop Grumman’s first Mission Extension Vehicle (MEV).

It is Russia’s penultimate launch of the year – the country’s smaller Rokot rocket, a distant relative of the Proton, will close the year by launching a cluster of low-orbit Gonets-M communications satellites on Friday, in what is expected to be its final flight.

Proton’s next launch is currently expected at the end of March next year, with a pair of Ekspress communications satellites. The next Elektro-L satellite will be launched in late 2021.

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