Satellites: The Earth should be monitored more carefully
ON APRIL 8th Envisat, Europe’s largest Earth-observing satellite, unexpectedly stopped talking to its users on the Earth below. Since then those users have been frantically trying to re-establish contact. They rely on Envisat’s radars and other sensors for a wide range of measurements, from the temperature of the oceans to the chemistry of the stratosphere. Scientists have used it to gauge ocean conditions for shipping and to investigate earthquakes; its data have been the basis of thousands of scientific papers.
Envisat had, unlike much of Europe, forgone early retirement: designed for five years of operation, it was on its tenth. Given its advanced years, you would think that planning for its eventual end would be well in hand. You would expect that successor instruments would already be in orbit, their measurements carefully cross-correlated with Envisat’s so that the elucidation of the scope and pace of global environmental change could continue seamlessly. You would be wrong.
Providing earthlings with a reliable, continuous record of their planet’s condition would seem a sensible aim in any circumstances. With the state of the atmosphere and oceans (see article) upset in ways whose consequences are not easily foreseen, and may well prove catastrophic, it becomes an imperative. You do not need to know every little thing about the environment in order to make policy about it. But only long-term measurements will allow researchers to get a reliable grip on the science of climate change and other environmental stresses. A firm grasp of the basic trends is a necessary precondition for understanding and for informed policy.
The governments that build and operate satellites like Envisat are not taking that necessity seriously. According to a damning report from America’s National Academies, the number of civilian Earth-observing satellites flown by the United States government looks likely to fall from 23 today to just six in 2020, and the number of instruments in orbit could drop from 90 to 20. The situation in Europe is somewhat less disastrous, but has its own problems. The European Space Agency is unwilling to move forward with a new generation of satellites that can monitor the environment continuously until the European Union promises to pay their operating costs.
Several of the parties involved must share the blame for this failure. The scientists who have a say in setting the priorities for Earth observation often fixate on pet projects and new sorts of measurement, as scientists are wont to do; that can lead to the vital business of long-term monitoring getting downplayed. Co-operation and co-ordination between agencies and countries is not what it should be. Then there is bad luck (or poor judgment): in recent years the National Aeronautics and Space Administration (NASA) lost two Earth-observing missions in a row because of a second-rate rocket for which it has yet to find an adequate replacement.
But the main culprits are governments, which are spending too little on the job. In 2010 the World Meteorological Organisation estimated that getting satellite observations up to scratch in terms of climate monitoring would cost an extra $1 billion a year. In the late 1990s NASA used to spend $2 billion a year on Earth observations, but by 2007 that had fallen to $1.3 billion (the costs of a successor to the Hubble Space Telescope rose from around $2 billion to $9 billion over roughly the same period). Properly co-ordinated, modest increases in the budget in America and the EU, and contributions from other powers (China is now flying very capable Earth-observing satellites; India and Brazil have been in the game for a while), could sort the problem out. Without them, the world will feel its way into the future blind and ill-prepared.
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