The European Space Agency (ESA) racked up a triple success today with the launch of its three-satellite Swarm mission, a four-year quest to study the Earth’s magnetic field in unprecedented detail.
The launch – by Rockot from Plesetsk Cosmodrome in north Russia, near the Arctic circle – went off with apparent perfection. Critically, the simultaneous release of all three satellites, which had been packed like sardines, just centimetres apart inside the rocket’s fairing, was achieved without collision.
With all three spacecraft transmitting and receiving their first maneouvering commands, a jubilant ESA director general Jean-Jacques Dordain tells programme participants and mission controllers gathered at the European Space Operations Centre (ESOC) in Darmstadt, about 20 minutes’ drive from Frankfurt, that recent positive experience suggests that the four-year Swarm programme could easily end up providing “a decade of scientific data, and many decades of science” as researchers around the world tap the measurements set to begin flowing from Swarm after its three-month commissioning phase.
Praising the quality of work from ESA’s own people, prime contractor Astrium and other industrial partners, Dordain added: “The only way to reconcile risk and success is expertise.”
In the two days following launch, mission control in Darmstadt will monitor all three satellites and begin activating their systems, including deployment of their distinctive 4m trailing booms, at the end of which are their sensitive magnetic field instruments, which need to sit as far from the body of the spacecraft as possible, to set in “clean” electromagnetic space.
During the mission, two of the units will chase each other in a 300km polar orbit. The third will be raised to about 530km, and its orbit will be let to drift over the mission to a much lower latitude, complementing measurements taken by the other two. The programme team will decide which spacecraft to push to the higher orbit later in the commissioning phase, after each unit’s specific performance in orbit is assessed.
Swarm is the fourth mission in ESA’s Earth Explorer series, after GOCE (gravity field, launched 2009), SMOS (soil moisture and ocean salinity, 2009) and Cryosat (sea ice thickness, 2010). The mission is designed to tease apart the effects on Earth’s magnetic field of its molten, rotating core, mantle, magnetosphere and solar wind.
The launch was delayed by 16 months owing to availability of the Rockot launcher, but the delay was put to good use to improve the spacecraft. According to Eckhard Settelmeyer, Earth observation director at Astrium Friedrichshafen, an earlier iteration of the super-rigid but very lightweight silicon carbide material used to make the boom was found to contain some ferromagnetic particles, which would have decreased by at least some degree the sensitivity of the onboard instruments. A more pure version was ultimately devised for the structure as launched.
Observers at ESOC watched a video link of the Plesetsk launch in silence, notably not breaking in to applause as the Rockot launcher left the pad. Rockot, derived from the Soviet SS-19 ballistic missile, has been used for years with extreme reliability but the Breeze upper stage, however, has in various versions been associated with a smattering of failed Russian launches. In the event, Swarm was delivered to orbit flawlessly; on hearing that communication from the first two satellites had been picked up by ESA ground stations in Kiruna, Sweden an hour and 32 minutes after launch and the third by Svalborg several minutes later – more or less precisely to schedule - programme stakeholders let rip with a hearty round of applause.
The critical phase of the mission runs through the weekend, and there are many orbital manoeuvres needed over the coming three months to array the spacecraft for their data-gathering mission. But for now, with the heart-in-throat launch phase completed without a hitch, Swarm is settling down into a phase where mission controllers are reasonably confident.
Or, at least, they are in control as ESA’s head of mission operations Paolo Ferri observed about an hour before lift-off, during the time running up to payload separation the mission control team were merely “passengers” – along for the ride but not in control. Indeed, during that first 1:32 following ignition at 12:02 Frankfurt time, most of them broke for a rather splendid buffet lunch.
Rockot’s performance is comparable to ESA’s new Vega light launcher, which flies from its spaceport in Kourou, French Guiana and has to-date made two trips to orbit. The next Earth Explorer – Aeolus, to measure wind profiles from space and attempt to validate weather forecasting models – will fly in 2015 by Vega, which is now ESA’s first-choice for this type of mission, to which it is ideally suited. Ferri says there isn’t much cost difference between the two (Vega is expected to settle down to €35-40 million per launch once it is running at its planned rate of three to four flights per year, after 2015), but the Vega is the clear political preference, as it keeps a mission – operationally and industrially – inside the European Union.
However, adds ESA’s Earth observations programme director Volker Liebig, missions will have to be designed to fly on either vehicle, whichever may be decided on at the start. That way, if a launcher becomes unavailable for any reason the mission has a chance of switching, and perhaps holding to schedule.