Carbon dioxide satellite launch fails through rocket fault
24 February 2009
The launch of NASA's Orbiting Carbon Observatory (OCO) satellite has failed after the Taurus XL rocket meant to deliver it into orbit did not jettison its casing at the planned time.
An artist's impression of the OCO satellite
The remains of the rocket and the satellite, which had taken a large team of scientists and engineers almost eight years to design and build, plunged into the ocean just short of Antarctica a few minutes after launch.
Scientists had hoped the satellite would provide revolutionary new insights into how carbon moves between the atmosphere, land and sea, by measuring carbon dioxide concentrations all over the world from space.
'We share the huge disappointment of the science community,' Chuck Dovale, NASA Launch Director, told journalists at a press conference. But he noted that 'the reason not everybody does this is because it [launching satellites] is hard. When you try to do it, sometimes you fail.'
John Brunschwyler, programme manager for the Taurus rockets, said the problem arose when the rocket was due to jettison the fairing of its third stage. The signal to trigger this was sent correctly, but for reasons that aren't yet known the rocket did not respond as expected.
The launch team had several signals the fairing had not detatched properly - wires that are supposed to break when this happens remained intact; temperatures on the fairing stayed at levels that suggested it was still attached to the rocket engines; and the rocket did not show the sudden burst of acceleration that would be expected when its weight was suddenly reduced by the loss of the bulky fairing.
'Because of that extra weight, the satellite did not have enough delta-V to make it into orbit,' commented Brunschwyler. In simple terms, the weight of the fairing meant the satellite couldn't go fast enough to escape from Earth's gravity field into orbit.
He said that identical fairing has been used many times before without trouble, and noted that 56 of 57 Taurus launches have gone successfully.
The first sign of trouble came when NASA launch commentator, George Diller, said, 'This is Taurus launch control. We have declared a launch contingency, meaning that we did not have a successful launch tonight.'
At the least, scientists' hopes for OCO will now have to wait until a replacement satellite is built and an opportunity arises to launch it. But it's far from certain that NASA will try again.
'We will discuss this with our international partners and take a careful look at what flight spares we have before deciding on how to move forwards,' said Michael Freilich, director of NASA's Earth Sciences division. 'We are committed to advancing earth system science, and we will have to take a long, thoughtful look at how we can best do that.'
Japan launched a satellite with similar goals, called the Greenhouse Observing SATellite (GOSAT), in late January. Freilich noted that GOSAT can provide similar data on CO2 to what OCO would have made available, and that in the years since work started on OCO, algorithms have been developed to let scientists get some CO2 measurements using other satellites that are already in orbit.
'The UK and European science community is a major partner in OCO and the loss of this instrument is a serious setback,' commented Professor John Burrows, director of Biogeochemistry Programme at the UK Centre for Ecology & Hydrology (CEH) and a co-investigator on the OCO initiative in his capacity as a member of the University of Bremen in Germany.
'The OCO mission aimed to make unique and high quality measurements of the atmospheric column of carbon dioxide at high spatial resolution,' he added. 'This information is urgently required to constrain our understanding of CO2 fluxes at the Earth's surface (uptake by both the land surface and the oceans) and emissions from fossil fuel combustion.'
"Detailed understanding of the surface emissions and uptake of CO2 is key to the accurate prediction of global climate change,' Burrows explained. 'We urgently need to invest in new European investment satellite based instruments to measure greenhouse gases from space as the first generation of such instruments, which have limited measurement capability, will stop operating by 2013."
'The failure of the OCO satellite is a major loss,' said Dr Chris Huntingford, climate modeller at CEH. 'The planned measurements from OCO would have helped refine our description of the carbon cycle in climate models, and thus allow more accurate predictions of future global warming,' he added.
He explains there is still considerable uncertainty in precisely how and where the land and ocean currently extract carbon dioxide from the atmosphere, and how this will be affected by climate change; OCO would have helped reduce this uncertainty.
'This is hugely disappointing, and I have the utmost sympathy with the team, who have put so much work into OCO over the last seven years,' commented Professor Paul Monks, an atmospheric chemist at the University of Leicester. 'But to try to look on the bright side, all these efforts have not been entirely wasted, as we should be able to do much of the same work with the GOSAT platform, which was successfully launched earlier this year.'
He notes that while the two systems were designed to complement each other, and hence have slightly different strengths, most of what would have been possible with OCO will be possible with GOSAT.
NASA will shortly launch an investigation to find out what went wrong. Officials confirmed that planned satellite launches won't take place until they understand what went wrong with this one. This includes Glory, a satellite intended to collect data on aerosols and black carbon in Earth's atmosphere and on the effects of changes in solar radiation on the climate. NASA had planned to launch this mission in 2009.
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