Sunday, 16 August 2009

Britain's ice man ready for a second space shot with rebuilt CryoSat probe

High hopes for global warming satellite after first probe plunged into the Arctic Ocean
Robin McKie, science editor
The Observer, Sunday 16 August 2009
It was rated one of the most damaging setbacks to hit the study of global warming: on 8 October, 2005, a £100m probe designed to measure ice thickness at the poles plunged into the Arctic ocean minutes after launch on an old Soviet SS-19 missile from Plesetsk, northern Russia.
The blow seemed irreparable but, as a result of a remarkable technological comeback, the satellite's UK creator, Duncan Wingham, will soon watch as a rebuilt version of his CryoSat probe, funded by the European Space Agency (Esa), makes its attempt to reach orbit.
"It is one thing to get the chance to build a satellite, but to get a second chance when things have gone wrong is remarkable," said Wingham, professor of Climate Physics at University College London.
Dignitaries and scientists, including Wingham, gathered at Europe's Esrin space centre in Frascati, Italy, to watch the original launch and cheered as television monitors showed the rocket rising into the atmosphere. Minutes after lift-off, however, transmissions from the probe stopped. A celebratory cocktail party was halted and anxious scientists huddled round monitors.
Then the truth emerged. The SS-19's second stage had failed to separate from the third stage, because of a computer programming error, and the whole assembly, including the satellite, had plunged into the Arctic ocean, the sea whose icy secrets CryoSat had been designed to study.
"This is a tragedy for all the scientists who have spent years putting together this mission," said an Esa official.
Wingham was the worst affected: he had worked on CryoSat since 1999 and his grey, shoulder-length hair and increasingly dejected demeanour made him the most distinctive figure at the launch gathering.
"I was stunned," he admitted last week. "Statistically there is an 8% chance things will go pop, that you will lose a satellite at launch – I hadn't worried about that. But it soon became clear that something had gone very wrong. I remember texting a friend, 'I think we've lost her'."
The main problem for Wingham was that, in order to keep down construction costs, Esa had not built a back-up probe. The project looked dead and buried, or – more precisely – drowned. But only a couple of hours after the failed launch, Wingham had started lobbying senior Esa executives to build a replacement.
"I told them, this satellite is too important to lose." Remarkably they agreed within 24 hours, and a few weeks later this decision was backed by Esa.
It was a testament to Wingham's persuasive powers and the design and importance of his satellite that this replacement was supported by the agency – though he is also quick to praise "scientific committees, delegates and organisations across Europe" for their campaigning as well. Thanks to them, CryoSat 2 will now rise like a phoenix, it is hoped, when it is launched in November, this time from Kazakhstan on a Dnieper rocket.
Like its predecessor, CryoSat 2 will be fitted with a device known as an interferometric radar altimeter. This will be used to measure the height of ice as it floats on the sea, which in turn will reveal the overall thickness of ice covering the Arctic ocean.
This latter measurement is crucial for scientists. Satellites have already shown that the geographical area of the Arctic covered by ice is dwindling significantly. However, other research suggests that this ice may also have been thinning markedly. If so, polar caps could shrink far more quickly than is predicted at present. Less solar radiation would then be reflected back into space from Earth's white ice caps, and the rate of global warming would jump. In addition, land ice sheets would no longer be propped by sea ice and would crumble into the oceans, raising sea levels round the planet.
"We are altering the Arctic climate far faster than anywhere else on Earth," said Wingham. "We're changing the whole structure of the Arctic ocean, but we still don't know what the consequences will be. We have to find out what is going on up there. CryoSat will do that."
However, it will take some time to achieve this goal. Once CryoSat2 is in orbit, it will take at least a year to return enough data to make reasonable estimates of the rate of ice thinning.
After three years, the satellite's expected lifetime, that data should be compelling, said Wingham. "And after that, you never know – we might even get CryoSat 3 and a whole series of follow-up satellites."