For visitors to any Paris air show, one of the most familiar Le Bourget landmarks is the full-scale air and space museum mock-up of an Ariane 5 rocket. While impressive enough, as any 50m structure would be in an otherwise low-rise landscape, the model is so familiar as to be invisible. After all, just about as tall and only a rocket's length away is a mock-up of the earlier Ariane 1, but who has ever paid that more than a passing glance at a Paris air show?
This is unfortunate, for while air museums tend to display classic models hanging from ceilings and decommissioned fighter jets on plinths, Le Bourget's Ariane 5 represents anything but the past. When the show opens, the dust will just have settled at the European Space Agency's Kourou, French Guiana spaceport from its latest Ariane 5 launch, to heft the fourth in its series of Automated Transfer Vehicles to the International Space Station. Loaded with some 7t of cargo - including about 3t of fuel - ATV 4 "Albert Einstein" will also nudge the ISS back up to its full orbit: at its very low orbit of little more than 400km there is still enough residual atmosphere to put a brake on its speed, so without a regular boost the station would soon fall out of orbit.
While Ariane 5 underpins much of ESA's activity and operates between the ISS and the 36,000km geostationary orbits of the telecommunications satellites for which it dominates the launch market, the heavy lifter is also being prepared for a much longer journey - to gaze into the aeons. As the launcher for the James Webb space telescope (JWST), an Ariane 5 will have to carry its cargo 1.5 million km from Earth. Sitting at one of the Lagrange points between the Earth and Sun, this much larger successor to the Hubble space telescope - its 6m (20ft) mirror will have an area almost three times the size of Hubble's - will orbit the Sun at the same rate as the Earth, keeping it in easy communication and, critically, keeping it cool with only one sunshade.
Ariane 5: familiar and reliable, but replaceable?
The Paris air show may not shed much light on the NASA-ESA-Canadian Space Agency JWST, but ESA personnel will be giving the project full attention in preparation for the July delivery of one of the instruments it is supplying. The NIRSpec near-infrared spectrograph will allow continuous observation of 100 galaxies to determine their chemical composition and the rate at which stars are forming. It will also allow astronomers for the first time to detect water on planets around other stars.
Falling water is unlikely to be rare at Le Bourget but ESA's Paris presence may shed a great deal of light on the Milky Way, as the agency prepares for the launch of its own Gaia space telescope. Described by ESA as a "discovery machine" charged with creating a 3D map of our galaxy, Gaia is scheduled for launch by Soyuz rocket from Kourou, in the second half of 2013. The five-year mission plan is to conduct a census of more than a billion stars, hopefully discovering hundreds of thousands of new celestial objects, such as extra-solar planets and failed stars. In our own Solar System, Gaia is expected to discover hundreds of thousands of asteroids.
We can also expect an update on Ariane 6. Earlier this year, EADS's Astrium division was awarded a €108 million ($140 million) ESA contract, formally making it prime contractor for the Ariane 5 ME (Midlife Evolution) project to boost the rocket's payload to geostationary orbit by a fifth, to 12t, from 2017 and to bridge the gap to an all-new Ariane 6, planned for service from 2021.
With any luck, ESA and Astrium will reveal details of what that new launcher will look like. The Ariane 6 concept calls for a modular design based on solid-fuel main stages that can be stored and assembled as required, and a cryogenic, restartable upper stage; the rocket is intended to have a payload capacity of 3-6.5t to geostationary orbit. The key advance is meant to be flexibility as Ariane 5 is reliable, but production is slow and each example must be manufactured for the performance of a specific payload.
ESA director general Jean-Jacques Dordain has labelled 2013 "a busy year for missions", and Paris should provide an early update on the Proba-V Earth observation mission, launched in May by ESA's new Vega light launcher. The V is for "vegetation", and it is hoped Proba-V, in its box the size of a washing machine, will provide the functionality of satellites many times its size.
The second half of 2013 will feature several other dramatic efforts. In addition to the launch of Gaia, the three-satellite Swarm mission, due for launch on 4 October from Plesetsk cosmodrome in Russia, promises to make the best survey yet of Earth's magnetic field and its evolution - at a time when it is showing signs of significant weakening.
The Swarm mission will survey Earth's magnetic field from October
The Swarm spacecraft, which will fly in three different polar orbits, are part of a broader focus to study the effect on Earth, Venus and Mars of solar activity during this current maximum in the Sun's 11-year cycle. ESA spacecraft including Swarm, Mars Express and Venus Express will observe the Sun and interior planets at the same time, providing an unprecedented view of how magnetic fields shield a planet's atmosphere from powerful solar eruptions. Solar storms can damage satellites, cause communications and even power blackouts and are responsible for the Aurora Borealis and Aurora Australis.
One highlight will hail from one of ESA's most successful missions, the Mars Express orbiter. On 2 June, ESA marked the 10th anniversary of the launch of a mission that had a nominal lifespan of 687 days (one Martian year) but which is still monitoring all aspects of the Martian environment in 3D images and assisting NASA's Curiosity rover in its exploration of the surface.
As the spacecraft has so greatly exceeded expectations, on 29 December ESA will risk the closest ever fly-by of one of Mars' moons, Phobos, to measure its mass distribution - critical in the event of any attempt at a sample return mission.
All the while, ESA astronaut Luca Parmitano will be watching from the ISS following his 29 May Soyuz launch from Baikonur, Kazakhstan alongside NASA astronaut Karen Nyberg and Soyuz commander Fyodor Yurchikhin. Parmitano's six-month stay in orbit will feature two spacewalks in July to install new equipment and retrieve experiments.
Parmitano will be unable to see the Ariane 5 mock-up from his outer space lair, of course, but with any luck he will be able to tell us if it is going to rain in Paris.
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