Nasa: a laser in space to measure melting ice on Earth

Nasa: a laser in space to measure melting ice on Earth

The US space agency Nasa has planned to launch on Saturday its most advanced laser ever placed in orbit, the ICESat-2, a billion-dollar mission to reveal the extent of melting ice on a land that heats. The half-ton satellite is to be powered by a Delta II rocket from the Vandenberg base of the US Air Force in California. The 40-minute window should open at 5:46 am local time (12:46 GMT). This mission is "extraordinarily important for science," Richard Slonaker, head of the ICESat-2 program at NASA, told reporters. For nearly ten years the agency no longer had an instrument in orbit to measure the thickness of areas covered by ice across the planet.

The previous mission, ICESat, was launched in 2003 and was completed in 2009. Thanks to it, scientists have learned that the pack ice is becoming finer and that ice-covered surfaces are disappearing from the coastal regions of Greenland and the Arctic. Antarctic. Since then, surveys have been conducted by aircraft on a mission called Operation IceBridge that flew over the Arctic and Antarctic. "Height measurements and ice evolution data" were collected, explained Nasa. But an update is urgently needed.

Read also Climate: when NASA is watching the house burn

Temperature increase

The increasing use of fossil fuels by humanity is resulting in a steady rise in greenhouse gas emissions, which are considered to be the main drivers of climate change. The average global temperature is increasing year after year, with the four warmest years of modern times being recorded between 2014 and 2017. The ice sheet is shrinking in the Arctic and Greenland, increasing the phenomenon of rising sea levels which threatens hundreds of millions of people in coastal areas around the world. The all-new ICESat-2 is expected to help scientists understand the extent of the contribution of ice melt to rising sea levels.

"We're going to be able to look specifically at how the ice is changing over a single year," said Tom Wagner, a researcher with NASA's cryosphere (ice) program. Combining these precise records with those collected over the years should give a boost to understanding climate change and improve predictions of rising sea levels, he added.

Read also The melting of Antarctic glaciers is accelerating

A very sophisticated laser

The ICESat-2 is equipped with two lasers – one of which is spare in case – much more advanced than the model on board the previous mission. Despite its power, the beam will not be hot enough to melt the ice from the orbital observation post deployed some 500 kilometers above the Earth, said NASA. He will shoot 10,000 times per second, as opposed to forty times for his predecessor, which will provide much more detailed data. Measurements will be taken every 70 centimeters on the trajectory of the satellite.

"The mission will gather enough data to quantify the annual changes in ice sheet thickness in Greenland and Antarctica, even if it is only four millimeters," the US Space Agency said. . In addition to the thickness and area of ​​the ice cover, the laser will also measure the slope on which it is laid. "One of the things we're trying to do is decipher the changes that are taking place inside the ice, and it's going to enormously improve our understanding of this, especially in areas where we do not know well. still how they evolve, "said Tom Wagner, citing the great depths of Antarctica as one of these mysterious areas. The mission is supposed to last three years but the satellite has enough fuel to last for a decade, if its officials decided to extend its life.

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