Spaceflight Insider

A new era in Earth observation set to begin with launch of Sentinel-1

The European Space Agency's Sentinel 1A spacecraft is set for launch tomorrow from Kourou, French Guiana. Photo Credit: S. Corvaja / ESA

A new fleet of European Space Agency (ESA) satellites, are set to deliver the wealth of data and imagery that are central to Europe’s new Copernicus Earth observation program. If everything goes according to plan? It will all start tomorrow with the launch of Sentinel 1. Tomorrow’s flight – is the first of the two Sentinel spacecraft which will comprise the Copernicus Program.

The first satellite in the series, Sentinel-1, is set to launch from Kourou, French Guiana on April 3 at 5:02:26 p.m. EDT (2102:26 GMT) on a Soyuz STA rocket.

The venerable Soyuz launch system has been tapped to send the first of the Sentinels on its way into the black of space. Photo Credit: S. Corvaja / ESA

The venerable Soyuz launch system has been tapped to send the first of the Sentinels on its way into the black of space. Photo Credit: S. Corvaja / ESA

Sentinel 1, carries an advanced radar instrument which will provide an all-weather, day-and-night supply of imagery of the Earth’s surface. When the next Sentinel satellite joins Sentinel 1 in 2015 the two spacecraft will be orbiting the Earth some 180° apart, taking images of  the entire surface of our world every six days.

As well as transmitting data to a number of ground stations across the globe for rapid dissemination, Sentinel 1 also carries a laser to transmit data to the geostationary European Data Relay System for continual data delivery. The C-band Synthetic Aperture Radar (SAR) aboard Sentinel 1 builds on ESA’s and Canada’s heritage SAR systems on ERS-1, ERS-2, Envisat and Radarsat satellites.

By offering a set of key information services for a broad range of applications, this global monitoring program makes a step change in the way we manage our environment, understand and tackle the effects of climate change, and safeguard everyday lives.

The mission will benefit a variety of services. For example, services that relate to the monitoring of Arctic sea-ice extent, routine sea-ice mapping, surveillance of the marine environment, including oil-spill monitoring and ship detection for maritime security, monitoring land-surface for motion risks, mapping for forest, water and soil management and mapping to support humanitarian aid and crisis situations.

The Sentinel 1 satellite will operate in a Polar, Sun-synchronous orbit around the Earth at an altitude of 430 miles (693 kilometers).

“Once safely in orbit around Earth, this new satellite will provide essential radar imagery for Europe’s Copernicus program – a program that will make a step change in the way we care for our planet,” said ESA’s Sentinel 1 Project Manager, Ramón Torres.

Sentinel 1 is 9 feet (2.8 meters) long, 8 feet (2.5 meters) wide, 13 feet (4 meters) high and it has two 32 foot (10 meters) – long solar arrays and a 39 foot (12 meter) – long radar antenna. The 5,700 pound (2,300 kilogram) Sentinel-1 satellite is expected to operate for about seven years.

Tomorrow's launch will mark the seventh time one  of the venerable boosters has taken off from Kourou, French Guiana. Photo Credit: Arianespace

Tomorrow’s launch will mark the seventh time one of the venerable boosters has taken off from Kourou, French Guiana. Photo Credit: Arianespace

This three-stage Soyuz-2 version of the rocket used at Europe’s Spaceport is a Soyuz-STA (which includes a Fregat upper stage). This will be the seventh Soyuz launch from Kourou, French Guiana since the rockets first launch in 2011.

The Soyuz launch area in Kourou is almost identical to the other Soyuz sites located in Kazakhstan and Russia, although it has been adapted to conform to European safety regulations.

The Sentinel 1 spacecraft was integrated onto the Soyuz STA booster on March 31. Photo Credit: S. Corvaja / ESA

The Sentinel 1 spacecraft was integrated onto the Soyuz STA booster on March 31. Photo Credit: S. Corvaja / ESA

The site consists of three main zones: the launch platform, the preparation area (known in Russian as монтажно-испытательный корпус; montazhno-ispytatelniy korpus, or MIK), where the three stages are assembled horizontally and checked out, and the launch control center itself.

The MIK is connected to the launch pad by a 2,296 foot (700 meter) – long railway, which is used to transport the rocket in a horizontal position. The launch control center is a kilometer from the pad. A 148 foot (45 meter) – tall mobile gantry provides a protected environment as the payloads are installed on the vertical launcher. Its internal movable work platforms provide access to the Soyuz at various levels.

The Russian Soyuz launcher is the workhorse of the Russian space program, in continuous production since the 1960s, and is a descendant of the R-7 rocket that launched Sputnik in 1957.

Soyuz has performed more than 1,700 manned and unmanned missions. It is designed to extremely high reliability levels for manned missions – today supporting operations to the International Space Station.

If everything goes as advertised tomorrow, this is what one should expect to see:

When the countdown clock reaches zero, the Soyuz STA booster will announce its intentions to the surrounding landscape. It will the roar aloft on a pillar of fire and begin its ascent up through the atmosphere.

At about a minute into the flight, the rocket will pass through the what is known as “max-q” – this is where the launch vehicle’s speed, when coupled with the pressure of the atmosphere – place the rocket and payload under the greatest amount of stress.

Just shy of two minutes after liftoff, stage separation will occur. Leaving the core stage to boost Sentinel-1 the remainder of the way to the spacecraft’s final destination.

The Soyuz 1A satellite will ride safely cocooned with the payload fairing. At about three minutes into the flight, the fairing is jettisoned. Image Credit: P. Carril / ESA

The Soyuz 1A satellite will ride safely cocooned with the payload fairing. At about three minutes into the flight, the fairing is jettisoned. Image Credit: P. Carril / ESA

After approximately two minutes total mission elapsed time, the Soyuz rocket’s four liquid-fueled (kerosene and oxygen) boosters which are attached to the core stage of the rocket will be spent. Now little more than dead weight – they will be jettisoned and will fall back to Earth.

At about three minutes and seven seconds into the mission – the fairing, the protective shield which covered the satellite through Earth’s atmosphere – is no longer needed. It will be jettisoned and left to fall back to Earth.

The Soyuz STA is a two-stage rocket with four strap-on boosters, all elements of which are fueled by a combination of RP-1 (a highly-refined form of kerosene) and liquid oxygen (LOX). The side-mounted boosters, which will burn for the first 118 seconds of tomorrow’s flight, before falling away, are each equipped with an RD-107A engine providing an estimated 188,502 lbs of thrust at near surface level.  The first stage, powered by a single RD-108A engine, generates some 178,161 lbs of thrust and should burn for a total of about 280 seconds. Finally, after the first stage has fallen away, the second stage will ignite, it will grant 66,993 lbs of thrust for approximately 230 seconds from its single RD -0110 engine. This should be sufficient to grant the Sentinel 1 spacecraft with all the velocity the spacecraft needs.

For the team who has worked to get Sentinel 1 on its way to orbit – the coming launch is the culmination of years of work.

“It is thanks to the outstanding technical excellence and collaborative efforts from industry and ESA that have brought us to this point, and we all look forward to a successful launch on 3 April,” Torres said.  “After being involved in the Sentinel-1 mission for more than seven years, these last few days before launch are very rewarding.”

 

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A native of the Netherlands, van Oene became ‘infected’ with the ‘space virus’ by an enthusiastic school teacher in 1981. Since 1994 he has been a freelance space photographer and writer for magazines and websites in Holland, Belgium and ‘Spaceflight’, the magazine of the British Interplanetary Society. van Oene is also the co-founder and CFO of SPACEPATCHES.NL. This Netherlands-based foundation currently produces all the official Soyuz crew patches for the Russian Space Agency, Roscosmos.

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