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Soyuz launches Resurs-P4 imaging satellite A Soyuz-2-1b rocket lifted off on a mission to revive Russia's prematurely defunct Resurs-P satellite constellation on March 31, 2024. The vehicle carried the fourth spacecraft in the series designed to provide the highest-resolution imagery of the Earth's surface among the country's civilian orbital assets.
The Resurs-P4 mission at a glance:
Development of Resurs-P4 On Dec. 22, 2014, Roskosmos issued contract No. 353-S083/14/407, assigning RKTs Progress, the country's leading developer of imaging satellites, the construction of the Resurs No. 4 and 5 satellites. The fresh pair was expected to introduce notable improvements in comparison with the trio of their predecessors. First of all, Roskosmos planned to replace a wide-angle camera, ShMSA-SR, with a resolution between 60 and 120 meters with a second high-resolution camera, ShMSA-VR, on vehicles No. 4 and No. 5 in response to demand from users. The Izvestiya newspaper quoted head of RKTs Progress Aleksandr Kirilin as saying that the new satellites would be equipped with a dual high-resolution lens system which would nearly double the swath of Earth's surface imaged by the satellite. The upgraded multi-spectral system would be supported by common avionics, Kirilin said. In addition, after technical problems with the data-transmission system on two previous satellites, RKTs Progress subcontracted the development of its new version to RKS Corporation, in Moscow, which promised to double the downlink rates for imagery from the satellite to the ground to 600 megabits per second. Roskosmos also dropped the Nuklon science instrument and the BRK AIS ship identification system hitchhiker payloads from the satellite's instrumentation package. (1036) Known specifications of the Resurs P4 satellite:
However, the start of active work on Resurs-P4 and -P5 coincided with the new Western sanctions on the supply of aerospace components, first of all electronics, to Russia after the Kremlin's annexation of Crimea. It was now required to either find replacements on the world market or to develop domestic equivalents. After around two years of searching for a solution, Roskosmos issued another contract (No. 353-8532A/16/279) on Dec. 2, 2016, ordering RKTs Progress to re-work the design documentation to incorporate domestically built avionics across seven different systems of Resurs-P satellites, including the imaging payload, radio equipment, onboard storage, telemetry measurement system and flight control computers. The effort required years to complete. As of 2015, launches of Resurs-P4 and -P5 were scheduled for 2017 and 2018 respectively, but in the course of 2017, the satellites were first promised to fly in 2018 and 2019 and then in 2019 and 2020, respectively. In early 2019, as the pair was reported to be well under construction, the launch of Resurs-P4 was set for November 2020, however by the beginning of that year, the launch had shifted to the first quarter of 2021. The situation was complicated by the fact that orbiting Resurs-P2 failed way ahead of its time in 2017, while Resurs-P3 was seriously crippled by technical problems in the same year. Ironically, the original Resurs-P1 lasted the longest, before going out of business in the Fall of 2021, thus leaving Roskosmos and its customers without a spacecraft in this class. By early 2022, Resurs-P4 was largely assembled and undergoing testing at RKTs Progress in Samara, but at least some of its equipment was not expected until Spring of that year, according to company head Aleksandr Kirilin. He likely referred to a new-generation data transmission system, which ended up being severely behind schedule. By the end of 2022, the launch of Resurs-P4 slipped to 2023, while Resurs-P No. 5 moved to 2025. Resurs-P development team:
Resurs-P4 launch campaign The Resurs-P No. 4 preparation at the launch site included the following steps:
On May 20, 2023, RKTs Progress announced that the assembly of the Resurs-P No. 4 satellite had been completed and that the spacecraft would be shipped to the Baikonur Cosmodrome in the near future. As of September 2023, the launch was expected in mid-November 2023, but by that time, it had slipped into 2024. In the early 2024, the launch was set for March 30, 2024. According to Roskosmos, the preparation for the fueling of the spacecraft started in Baikonur around March 7, 2024, and the spacecraft itself was delivered to the launch site by March 11, 2024. At the time, the launch was still expected on March 30, 2024, but on March 27, the KazTAG news agency reported that it had been postponed for 24 hours to March 31, 2024, apparently due to the processing of the launch facility at Site 31, after a 48-hour delay of the Soyuz MS-25 launch from March 21 to March 23, 2024. The rollout of the Soyuz-2-1b rocket to the launch pad took place as planned on March 29, 2024. A backup launch opportunity was available exactly 24 hours later.
A Soyuz-2-1b rocket, carrying the Resurs-P4 satellite, lifted off on March 31, 2024, at 12:36:45.626 Moscow Time (5:36 a.m. EDT) from Site 31 in Baikonur. To deliver Resurs-P4 into a near-polar orbit, the launch vehicle headed almost exactly north from Baikonur to align its ground track with an orbit inclined 97.276 degrees toward the Equator in order to give the satellite an almost global coverage of the Earth's surface. The four strap-on boosters of the first stage dropped off less than two minutes after the liftoff and then fell into Drop Zone No. 120 in Aktyubinsk and Kostanai Regions in Kazakhstan. The core (second) stage of the rocket continued firing until 4.7 minutes into the flight and then separated, reentering the dense atmosphere and crashing in Drop Zone No. 401 near the border of the Sverdlovsk and Perm Regions of Russia. In the next two seconds, the tail section of the third stage, which served as an interface with the core stage, split into three sections and separated from the third stage, aiming to impact same drop zone as the second stage. The same area also received the two halves of the payload fairing, which were jettisoned 1.2 seconds after the separation of the tail section. After firing for 9 minutes 17 seconds, the third stage firing completed the orbital insertion of the satellite into a 260 by 475-kilometer initial orbit, releasing it around three seconds after the engine cutoff. Operations in orbit During the fifth day of the flight, Resurs-P4 will likely fire its own propulsion system during the 54th and 64th orbits to enter a near-circular Sun-synchronous orbit with an altitude of between 468 and 477 kilometers. The orbital parameters should allow the satellite to revisit same areas of the Earth under similar lighting conditions from the Sun, thus resulting in consistent imagery. Resurs-P4 has a projected life span of at least five years and should have a capability for a controlled deorbiting over a safe area of the ocean after the end of service. As expected, between April 2 and April 3, 2024, Resurs-P4 was tracked maneuvering from the 291 by 465-kilometer elliptical orbit to a near-circular 464 by 469-kilometer orbit. By April 4, 2024, the satellite climbed to a 469 by 472-kilometer orbit. Its orbital inclination remained largely unchanged at 97.18 degrees. On April 5, 2024, Roskosmos announced that the Geoton-L1 high-resolution instrument produced its first images and, on April 19, the State Corporation said that Geoton-L1 aboard Resurs-P4 had been used for imaging city of Orsk devastated by a catastrophic flood.
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