A new look at Earth and a reverence for Vega – Libération

We are moving into a new era at the Guiana Space Center in Kourou, where two historic launches took place this summer: the takeoff of the very first Ariane 6 early July, and that of the very last Vega at the beginning of September. The rocket is to put the Earth observation satellite into orbit during the night from Tuesday to Wednesday Sentinel-2Cbefore definitively handing over the baton to its successor in the family of European light launchers: Vega-C.

Tarnished image

Thirty meters high, three meters in diameter, and twelve years of service: Vega has had a successful career in Guyana with one to three launches per year since 2012. It is a modest rocket, built by the Italian Avio, and designed specifically to launch small satellites into low Earth orbit. But its image has been tarnished by some recent failures: the Emirati satellite Falcon Eye 1 was lost in July 2019, then two satellites including the French scientific mission Taranis, which was to observe storms from space, failed to enter orbit at the end of 2020.

Vega thus contributed to what is now called the “launcher crisis”, which puts Europe in the difficult situation where almost no rocket is capable of taking off from Kourou. The big Ariane 6 has been delayed for years whileAriane 5 has already been retired since 2023; the intermediate pitcher Soyuzmanufactured by the Russians and marketed by the Europeans, has left Kourou since the start of the war in Ukraine, and the small Vega spent months grounded while investigations were carried out into the causes of the failures and corrections were made.

“Trust”

There is no doubt that all the world’s attention will have been focused on the preparations for this final launch, scheduled for Tuesday at 10:50 p.m. local time (Wednesday at 3:50 a.m. Paris time), to close the story of Vega on a success. But it will then be necessary to redouble efforts so that the new version Vega-C to get Europe out of this black series. A little higher and a lot more powerful (430 tons of take-off thrust compared to 230 tons previously), Vega-C opens up new perspectives for orbiting on paper. Once in the sky, it’s a different story… At the end of 2022, for only its second flight, Vega-C got off to a very bad start with an engine problem that prevented it from properly launching the French satellites Pleiades Neo number 5 and number 6. She hasn’t flown since.

After much analysis and corrections, “We did a conclusive test of the Zefiro engine in May and we will do another one at the beginning of October. We are very confident in its success.”assures Toni Tolker-Nielsen, director of space transportation at the European Space Agency, at a press conference. He aims for a return to flight of Vega-C “from the end of November, for a Sentinel satellite of a fairly new model, which could not be launched with Vega” first of the name.

Divorce

What is certain is that the organization will change. Until now, it was the Arianespace company (a subsidiary of Arianegroup) that marketed the flights of European launchers. Ariane et Vega – that is, which was responsible for finding customers looking for a reliable rocket to put their satellites into orbit, negotiating the price of the takeoff, welcoming customers to Kourou to install the satellite in the rocket fairing and prepare for the big day… But after an amicable divorce signed at the Seville space summit in November, Arianespace will now leave it to the Italian manufacturer Avio to sell its own rockets with uncertain reliability. Arianespace is keeping only the large Ariane in his wallet.

The transition will be gradual. “We still have responsibility for six launchessummarizes Stéphane Israël, CEO of Arianespace: two before the end of this year and four next year, before finally handing over to our partner Avio.”

Observing the Earth

For the first of these six transition launches, the Sentinel-2C satellite bears a major responsibility. It must support and then replace the satellites Sentinel-2A et 2B as part of the European Earth observation programme, called Copernicus. Experts in monitoring land, water and the Earth’s atmosphere, the «Sentinel 2» are designed to operate as a duo. The first (the “A”) was launched in 2015 and the second (the “B”) followed in 2017. Each spacecraft has a theoretical lifespan of ten years – which means that, even if the European Space Agency hopes that they will last much longer than that before giving up the ghost, it is time to start planning for their succession. It has already been nine years since the launch of Sentinel-2A…

“We want to avoid one of the two breaking down at all costs.”explains Mauro Facchini, head of the Copernicus programme at the European Commission. In addition to the crucial interest, from a purely scientific point of view, of the Copernicus programme in monitoring the climate for example, many companies base their commercial activity on the data acquired by the Sentinel satellites. “Many manufacturers need data availability to be guaranteed over the long termcontinues Mauro Facchini. Running Sentinel 2-C is a way to anticipate problems that might arise.” by ensuring redundancy. A fourth device, Sentinel-2D, is already on track, “ready to be launched in a few years.”

Backup satellite

For the moment, there is no question of bringing Sentinel-2A, the oldest satellite in the series, back to Earth as long as it is still functional in orbit. A whole strategy has therefore been established to transform the current duo of satellites into a trio, and to make them work as efficiently as possible. “2B will be brought closer to 2C so that they operate together initially: they will take the same images of the Earth. This allows for a seamless transition from one satellite to the other.”explains Constantin Mavrocordatos, project manager of Sentinel 2. Then 2C will officially enter service, and 2-A will become the backup satellite. The old “2A will be placed in the same orbit as the other two to follow their path but slightly offset. It will not be active and will be able to ensure continuity of service in the event of a problem.”

Color and high resolution images of Sentinel 2 allow to photograph “all of the Earth’s land and coastal waters every five days”recalls the ESA on its website, because the two satellites are always positioned on one side and the other of the Earth, diametrically opposed. They observe in particular land use, the evolution of agriculture and ecosystems, and help monitor natural disasters such as forest fires, floods, volcanic eruptions, etc. They also observe glaciers, snow cover and water pollution.