Rockot delivers Sentinel-5P
After a long string of political problems, a veteran Soviet ballistic missile converted into a space launcher successfully delivered into orbit a European Earth-watching satellite for the world's largest environment-monitoring constellation after a liftoff from Plesetsk on October 13, 2017, at 12:27:30 Moscow Time.
Sentinel-5P mission at a glance:
Political problems for Sentinel-5P
According to original plans, the launch of the Sentinel-5 satellite on the Rockot booster was expected in 2014. As of January of that year, the mission was expected at the beginning of 2016 and it was later planned for mid-April and mid-July 2016. However like Zenit, Dnepr and other space vehicles built in cooperation between Russia and Ukraine, the Rockot program was affected by Moscow's annexation of Crimea. Rockot used a Ukrainian built flight control system on its Briz-KM upper stage which was responsible for the operation of all three stages of the rocket.
Still, after the Russian-Ukrainian conflict broke out in 2014, six Rockot missions were able to fly. However, Moscow-based GKNPTs Khrunichev, which developed Rockot, had an increasingly hard time getting necessary avionics and other assistance from Ukraine as the bloody conflict on the border between the two former Soviet republics continued unabated.
After several delays of the Sentinel-5P mission, it reportedly required a personal intervention from the Ukrainian president Petro Poroshenko to authorize the shipment from Ukraine to Russia of the necessary hardware for the launch, a European source said. Under the cover of that exception, GKNPTs Khrunichev apparently attempted to procure from Ukraine extra sets of onboard equipment for the Rockot as backup units. Obviously, if the first set of Ukrainian avionics intended for the Sentinel-5P mission operated as planned, the extra hardware would be critical for flying Russia's own future missions on the Rockot, which otherwise could be grounded by the anti-Russian sanctions. With the assistance of European officials, a deal to acquire the Ukrainian hardware had been successful, but all the additional negotiations further delayed the Sentinel-5P mission. There were also reports that problems with components of the Rockot booster provided by the Russian company PO Polyot in the city of Omsk further contributed to the delays of Sentinel-5P.
All the problems with the Sentinel-5P mission reportedly prompted European space officials to consider switching the follow-on Sentinel-3B spacecraft from Rockot to the much more expensive European Vega launcher, even if this would mean its own associated delays. The European Commission, which uses the Sentinel satellites, was expected to make a decision on the launcher for Sentinel-3B this month.
Around the beginning of February 2017, Sentinel-5P was mated for the first time with its launch vehicle adapter designed to serve as an interface with the Briz-KM space tug. The so-called fit checks were conducted at facilities of Intespace in Toulouse, on February 3 and 4.
On May 25, 2017, the Russian government issued formal decision No. 1020-r, authorizing the military personnel in Plesetsk to support the Sentinel-5P mission. At that time, the launch was expected on Sept. 21, 2017, but by July it was reported to be scheduled between Oct. 9 and Oct. 31, 2017. In a manifest published by Roskosmos on Aug. 28, 2017, the launch of the Sentinel-5P satellite was identified as under consideration between October 9 and 12, 2017.
At the end of August 2017, the Sentinel-5P's "advanced team" arrived at Plesetsk and the satellite itself departed England for Plesetsk on August 30, 2017. The container with the satellite was driven from Airbus Defense and Space facility in Stevenage, where the satellite was built, to London Stansted Airport where it boarded an Antonov-124 transport plane. After a short stop in Moscow for customs, the aircraft carrying the satellite and its support equipment landed at Arkhangelsk's Talagi airport on August 31. The container with the spacecraft was then loaded on a train for the 250-kilometer trip to Plesetsk, which took around 1o hours to complete due to speed restrictions when carrying this sensitive cargo. The spacecraft arrived at Plesetsk on the morning of October 1, 2017. After the container was cleaned, it was moved into a dedicated clean room facility, No. 101 B inside the spacecraft processing building. After a week of preparatory work, the satellite was extracted from its container and successfully powered up. The satellite then went through pneumatic and electric tests. Specialists also conducted communications checks between the satellite and its mission control.
Irreversible operations of the Sentinel-5P launch campaign started on Sept. 20, 2017, with preparations for fueling of the spacecraft with hypergolic propellant. Loading of the propellant was successfully completed by a team from the ArianeGroup site in Lampoldshausen on September 22.
During the same week, the launch vehicle underwent a dry run on the launch pad which proved that the Briz-KM upper stage fitted to the booster. The flight version of Briz-KM then made a 30-kilometer trip by rail to its fueling station.
On September 26, the Director General of the European Space Agency publicly announced that the launch of the Sentinel-5P was set for October 13, 2017.
Joint operations between the launch vehicle and the spacecraft began on September 28, when Sentinel-5P was integrated with the launch vehicle adapter.
By October 2, the satellite and its adapter were mounted onto the Briz-KM upper stage and the next day, the spacecraft was encapsulated under the launch vehicle payload fairing, completing the assembly of the upper composite section.
Once the upper composite was assembled and a mission logo was glued to the payload fairing, it was signed by the members of the Sentinel launch team on October 5. The structure was then wrapped into thermal blankets to protect it from the elements during the trip to the launch pad.
The upper composite with the Sentinel-5P made the four-hour rail trip to the launch complex 14P25 at Site 133 on the morning of Oct. 7, 2017. The mobile service tower was then used to lift the satellite and its Briz-KM upper stage and mount it on top of the two-stage booster.
Electrical check-outs and calibration runs on Sentinel-5P were then conducted in order to confirm the flawless functioning of the spacecraft after its rollout to the launch site. According to ESA, the spacecraft team was expected to pay regular visits to the payload on the pad until shortly before launch in order to ensure the continuous purging of the satellite's main instrument with nitrogen gas as a protective measure against contamination on the ground.
In the meantime, the personnel of the Russian Space Forces installed the pipelines connecting the rocket with the fuel and oxidizer tank storage.
The dress rehearsal for the launch was planned for October 10, 2o17. The fueling of the first two rocket stages was scheduled to take place two days before launch and the Russian State Commission overseeing the launch was to meet on October 12 to issue a formal permission for the liftoff.
Sentinel-5P finally lifts off
The launch of the Rockot booster with a Briz-KM upper stage took place as scheduled on Oct. 13, 2017, at 12:27:30 Moscow Time (09:27 GMT; 11:27 CEST; 5:27 a.m. EDT) from Site 133 in Plesetsk. The vehicle carried the 900-kilogram Sentinel-5P satellite for the European Space Agency, ESA. Despite overcast skies over the launch site, very low winds allowed mission to proceed, ESA said.
Following the ignition of the first stage, the rocket emerged from the Transport and Launch Container which is attached to the stationary column holding it in place.
After a short vertical ascent, the rocket headed northwest to align its ground track with an orbital inclination of 98.75 degrees toward the Equator, in order to reach a near Sun-synchronous orbit.
The first stage of the rocket separated two minutes and two seconds into the flight, followed by the separation of the payload fairing, which split in two halves and dropped off nearly three minutes into the flight.
The rocket's second stage completed its burn and separated five minutes and five seconds after liftoff (L+319 seconds), leaving the Briz-KM stage and its payload on a suborbital trajectory. Moments later, Briz-KM initiated its first firing inserting itself and the satellite into an initial orbit.
The second maneuver of the Briz-KM was conducted around an hour later, when the stack reached an apogee of its initial orbit and made it nearly circular.
Upon entering its target orbit, which was expected to have an altitude of 824 kilometers and an inclination of 98.7 degrees toward the Equator, pyrotechnic charges of the special clamp-band mechanism fired, separating the spacecraft from its Briz-KM upper stage at 13:46 Moscow Time (6:46 a.m. EDT). Then, 93 minutes after liftoff and 14.5 minutes after the separation from the upper stage, Sentinel-5P established first contact with its mission control center in Darmstadt, Germany, via a ground station in Sweden at 11:01 GMT (7:01 a.m. EDT).
The NORAD data then showed an object associated with the launch in a 816 by 820-kilometer orbit. Another object was in a 413 by 767-kilometer orbit, which could be the Briz-KM stage after it had entered a burial orbit.
Design of the Sentinel-5P satellite
The Sentinel-5P, where P stands for "precursor" is the sixth member of the Copernicus remote-sensing constellation developed by the European Space Agency for monitoring various aspects of the Earth's environment.
This particular spacecraft is designed to conduct global mapping of the chemical composition of the Earth's atmosphere with a resolution as high as 7 by 3.5 kilometers every 24 hours, ESA said. That accuracy will allow to monitor air pollution over individual cities.
Within the atmosphere monitoring capabilities of the European Space Agency, the Sentinel-5P will serve as a bridge between the ENIVISAT and EOS-Aura missions and the more sophisticated Sentinel-5 satellite to be launched no earlier than 2020.
As its main payload, the Sentinel-5P carries the state-of-the-art Tropospheric Monitoring Instrument, Tropomi, which is an absorption spectrometer, developed at Dutch Space. The instrument is designed to map a multitude of trace gases such as nitrogen dioxide, ozone, formaldehyde, sulphur dioxide, methane, carbon monoxide and aerosols. It will allow an increased frequency of cloud-free observations required for the study of troposphere variability.
The range of sensitivity for the Tropomi spectrometer on the Sentinel-5P satellite.
The mission will contribute to EU Copernicus services such as volcanic ash monitoring for aviation safety and for services that warn of high levels of UV radiation which can cause skin damage. In addition, the measurements will improve knowledge of important processes in the atmosphere related to the climate and to the formation of holes in the ozone layer.
The scientific side of the mission is managed by Royal Netherlands Meteorological Institute, KNMI, and the Netherlands Institute for Space Research, SRON.
Tropomi is a collaboration between Airbus Defense and Space Netherlands, KNMI, SRON and the Netherlands Organization for Applied Scientific Research, TNO. It was commissioned by the Netherlands Space Office, NSO, and ESA. Airbus Defense and Space Netherlands were the principal contractor for developing the instrument, while scientific management is in the hands of KNMI and SRON. Funding for TROPOMI was provided by the Ministry of Economic Affairs, the Ministry of Education, Culture and Science and the Ministry of Infrastructure and the Environment in the Netherlands.
The Dutch government has invested a total of €80 million in the development of the space project under a 2009 agreement with ESA. This allowed the NSO to award the contract to the consortium that developed Tropomi.
Known specifications of the Sentinel-5P satellite:
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A logo for Sentinel-5P launch on the Russian Rockot booster. Credit: ESA
An internal design of the Sentinal-5P satellite. Click to enlarge. Credit: ESA
The Tropomi instrument for Sentinel-5P. Click to enlarge. Credit: ESA
A fully assembled Sentinel-5P satellite. Credit: ESA
Pre-launch processing of the Sentinal-5P satellite in Plesetsk in September 2017. Click to enlarge. Credit: ESA
Sentinel-5P is being integrated with Briz-KM upper stage on . Click to enlarge. Credit: ESA
An artist rendering depicting payload fairing separation during the ascent of the Sentinel-5P satellite into orbit. Click to enlarge. Credit: ESA
Sentinel-5P rides Briz-KM upper stage. Credit: ESA
Sentinel-5P separates from Briz-KM upper stage. Credit: ESA
Click to enlarge. Credit: ESA
Sentinel-5P lifts off on Oct. 13, 2017. Credit: ESA