Arianespace will make its third and final orbital launch of 2024 on Thursday, Nov. 5, as the Vega-C rocket returns to flight two years after its previous mission failed to reach orbit. Thursday’s launch will carry Sentinel-1C, a radar-imaging satellite for the Copernicus Earth science program. Liftoff is scheduled for 21:20 UTC (6:20 p.m. local time) from Kourou, French Guiana, with spacecraft separation expected 103 minutes later.
The launch, which is designated VV25, had been scheduled for Wednesday, Dec. 4, but was postponed due to an issue with the mobile gantry. This flight comes during a time of transition for the European satellite launch provider.
Development delays with the Ariane 6 rocket and Vega-C’s failure during its previous launch in December 2022 have meant that the company’s previous-generation Ariane 5 and Vega vehicles were both retired before their replacements were fully in service. The political fallout from Russia’s 2022 invasion of Ukraine has also suspended Arianespace’s operation of the Soyuz rocket out of Kourou.
VV25 is the third mission for Vega-C, which first flew in July 2022. An enhanced version of the earlier Vega rocket, it features new, larger, first and second stages, upgrades to the third and fourth stages, and a larger payload fairing. The first stage is powered by a P120C solid rocket motor (SRM), the same motor used in Ariane 6’s boosters, providing a measure of commonality across Arianespace’s fleet intended to help drive down costs. The second stage is a Zefiro Z40, instead of the smaller Z23 used on the original Vega.
Although Vega-C’s first launch was successful, its second was unable to reach orbit. During this mission, the Z40 experienced a loss of thrust from 151 seconds after liftoff. An investigation after the mishap determined that a carbon-carbon material used in a throat insert in the motor’s nozzle had been unexpectedly eroded. Vega-C has been grounded while the insert was redesigned to use a different carbon-carbon material which was previously used on the Z23.
Since then, Arianespace has launched only five missions prior to Wednesday’s: the final two Ariane 5 rockets flew in April and July 2023; the original version of Vega made its last two launches in October 2023 and September 2024; and Ariane 6 lifted off for its first demonstration flight in July 2024. This latter launch was declared a success, however, the rocket’s upper-stage engine failed to restart for a planned deorbit burn at the end of the mission after its auxiliary propulsion unit shut down during a cost phase after an out-of-limit temperature sensor reading.
Despite the deorbit issue, Arianespace is moving forward with the next Ariane 6 mission, which will be the first to carry a customer payload — a French military reconnaissance satellite. This is currently slated for the end of February.
Sentinel-1C during integration with Vega-C’s payload adaptor. (Credit: ESA/CNES/Arianespace/CSG)
The Sentinel-1C satellite that will launch aboard VV25 is the third in a series of radar imaging satellites that form one of the core elements of the Copernicus program, which forms part of the European Union’s space program — carried out in partnership with the separate European Space Agency (ESA).
Copernicus uses a fleet of satellites to carry out studies of the Earth and its environment. The Sentinel-1 satellites carry radar-imaging payloads, Sentinel-2 satellites carry out optical imaging, Sentinel-3 spacecraft are used for land monitoring and oceanography, and Sentinel-6 missions collect sea level data through radar altimetry.
Sentinel-4 and Sentinel-5 missions will collect data on the composition of the atmosphere. These will not be dedicated satellites but will instead fly as instruments on weather satellites in geostationary and polar orbit respectively. A Sentinel-5 Precursor mission was launched in 2017 to resume the collection of this data after the Envisat satellite had abruptly ceased operations in 2012. The first weather satellites carrying Sentinel-4 and 5 payloads are expected to begin launching next year.
Higher-numbered Sentinel missions have been commissioned for specific research objectives as part of the project’s next generation of satellites.
The initial Sentinel-1, 2, and 3 satellites were launched between 2014 and 2018, with a pair of each type of spacecraft deployed in separate launches to carry out complementary research. Sentinel-1A was deployed by a Soyuz-Fregat rocket flying from Kourou in April 2014, with Sentinel-1B following two years later. Having been designed for between seven and 12 years of service, Sentinel-1A remains in operation while Sentinel-1B was deactivated in 2022 after an electrical failure the previous December had left its radar imaging system inoperable.
Sentinel-1C undergoing preparations for testing at Thales Alenia Space. (Credit: ESA/M. Pedoussaut)
A new series of satellites are being launched to replace those already in orbit. This began with the deployment of Sentinel-2C in September on the final launch of the original Vega rocket and continues with Wednesday’s launch of Sentinel-1C. This will replace Sentinel-1B and bring the Sentinel-1 part of the constellation back up to full strength before Sentinel-1D joins it in orbit as the replacement for Sentinel-1A. A fourth Sentinel-2 and another pair of Sentinel-3 satellites are also expected to be deployed on future launches.
Like Sentinel-1A and 1B, the Sentinel-1C satellite carries a C-band synthetic aperture radar (SAR) payload, allowing it to image the Earth’s surface without consideration for light conditions or cloud cover. Uses for Sentinel-1 data have included monitoring land use, tracking shipping and sea ice, studying ocean phenomena such as algae blooms and oil slicks, and disaster management.
Sentinel-1C introduces a new capability for the constellation with the addition of Automatic Identification System (AIS) receivers, allowing it to collect and relay tracking data from ships at sea, which will complement the use of radar to determine their positions. The satellite will also carry out an on-orbit test of the Galileo navigation system’s High Accuracy Service (HAS) signal which will attempt to determine the satellite’s position to within 20 cm.
The four-stage Vega-C rocket will launch from the Zone de Lancement Vega (ZLV) at the Centre Spatial Guyanais (CSG), or Guiana Space Centre, located near Kourou in French Guiana. ZLV was rebuilt ahead of the first Vega launch in 2012, having served from 1979 to 1989 as a launch pad for the Ariane 1, 2, and 3 vehicles. Before that, it was the site of an earlier pad used by the Europa II rocket for a single unsuccessful launch in 1971.
Vega-C uses three solid-propellant stages: P120C, Zefiro Z40, and Zefiro-9A, which burn sequentially. The fourth stage, the Attitude and Vernier Upper Module+ (AVUM+) has a restartable liquid-fuelled RD-843 engine to provide for a precise orbital insertion. At the nose of the vehicle, Sentinel-1C is enclosed within a 3.3-m diameter payload fairing which will protect it during the climb through the atmosphere. The fairing will separate shortly after third stage ignition.
After the third stage burns out and separates, AVUM+ will make a series of three burns to insert Sentinel-1C into its planned orbit. The first will begin at the eight-minute, 16-second mark in the flight — about 68 seconds after third stage separation. Following a coast phase, a second burn will commence 53 minutes and 27 seconds after liftoff, with a third burn at one hour, 40 minutes, and 29 seconds mission elapsed time completing the ascent.
Separation of the Sentinel-1C satellite is expected one hour, 43 minutes, and 41 seconds after launch. The first signals from the satellite should be acquired about 13 minutes later as it transitions into the on-orbit checkout and commissioning phase of its mission.
(Lead image: Vega-C with Sentinel-1C at the launch pad. Credit: ESA/Manuel Pedoussaut)
The post Europe’s Vega-C to return to flight with Sentinel-1C mission appeared first on NASASpaceFlight.com.
Comments
Post a Comment