[ad_1]
This weekend, NASA plans to launch a spacecraft that will use half a dozen light green laser beams to measure the seasonal and annual variations of the frozen poles of the Earth.
The mission, called the Ice Elevation Satellite, Clouds and Lands (ICESat-2), will take incredibly accurate measurements of the depth of the ice cap, allowing scientists to add the lost third dimension when they look at aerial or spatial images. spread of ice.
It's a crucial piece of information when it comes to making an accurate picture of ice changes over time, because smaller ice is as troubling as shrinking ice. But the fact that it is an important type of data does not mean that it is easy to collect, which is part of NASA's affection for space lasers. [How Satellites Watched Birth of a Giant Iceberg in Antarctica (Photos)]
ICESat-2 will only be equipped with one instrument, called Advanced Topographic Laser Altimetry System (ATLAS). ATLAS produces six laser beams of bright, finely tuned green light, which it broadcasts to bounce off the surface of the Earth. (Do not worry, the laser is not strong enough to melt the ice.)
Many of these photons are lost, scattering in all directions. But some precious bounce perfectly to find the satellite. Scientists can then translate the incredibly precise measurement of the travel time of each photon – within a billionth of a second – of the space probe into the distance traveled, essentially by measuring the height of the earth's surface at that location.
For sea ice, the top of the ice is compared to the surface of the ocean that surrounds it. Then scientists can calculate how much extra ice should be hidden by floating in the water. For the Earth's ice, the process is a bit more complicated but works on similar principles.
The spacecraft produces 10,000 photon pulses per second and for each pulse the same process occurs. ICESat-2 will orbit from one pole to the other, taking measurements along the way, but offering the densest height charts near the poles.
Every three months, the spacecraft will travel a total of 1,387 orbital trajectories, then begin to retrace its steps, ensuring that it revisits the same band of ice in 91-day increments. And because the instrument creates six separate laser beams in three pairs, scientists can adapt the data if the satellite ends up moving away from its intended trajectory.
This is a major advance over the original ICESat mission, which ran from 2003 to 2010, but only produced data using a single laser beam. Nevertheless, this mission provided crucial evidence that the Greenland icecap was thinning.
The ICESat-2 mission cost a little over a billion dollars and the spacecraft is about the size of a smart car. The initial mission is expected to last three years, starting approximately two months after launch to allow the team to calibrate the instruments. That said, the spacecraft carries enough fuel for 10 years, so the mission could be extended.
The satellite is due to take off from Vandenberg Air Force Base in California on Saturday, September 15, during a launch window that opens at 5:46 am local time (8:46 am EDT and 12:46 GMT) and will last 40 minutes. . You can watch the live launch from 8:10 am EDT (12:10 GMT) on Space.com, courtesy of NASA TV. The launch will be the last voyage of the Delta II rocket, which has been flying for 29 years.
Email Meghan Bartels at [email protected] or follow her @meghanbartels. follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.
[ad_2]
Source link
