|January 18, 2016|
SpaceX launches satellite to monitor sea level, global warming
|A SpaceX Falcon 9 rocket thundered away from a foggy California coast Sunday and boosted a $364 million science satellite into orbit Sunday, the latest in a series of spacecraft designed to precisely measure sea levels around the world -- a key indicator of global warming -- and to monitor ocean conditions responsible for extreme weather.|
It was the second SpaceX launch in less than a month and the second in a row to attempt recovery of the Falcon 9's first stage. During a launching Dec. 21 at the Cape Canaveral Air Force Station in Florida, a Falcon 9 first stage carried out the company's first successful touchdown on land.
Because environmental impact requirements at Vandenberg Air Force Base in California are still being worked out, SpaceX used a landing barge -- the "Just Read the Instructions" -- for Sunday's recovery. SpaceX founder Elon Musk said the descent proceeded smoothly, but one of four landing legs did not lock in place and the rocket tipped over after touchdown.
"Definitely harder to land on a ship," Musk tweeted. "Similar to an aircraft carrier vs land: much smaller target area, that's also translating & rotating. However, that was not what prevented it being good. Touchdown speed was ok, but a leg lockout didn't latch, so it tipped over after landing."
Amazon-founder Jeff Bezos, whose company Blue Origin also is focused on recovery and reuse of rocket stages, tweeted: "Impressive launch and @SpaceX will soon make Falcon 9 landings routine - so good for space! Kudos SpaceX!"
By recovering, refurbishing and eventually relaunching rocket stages, Musk hopes to dramatically reduce launch costs. The rocket stage that landed in Florida last month was mounted on SpaceX's launch pad at Cape Canaveral last week and its nine-first stage engines successfully test fired Saturday.
But given the mixed results Sunday, SpaceX still has work to do. The company's record now stands at one success on land, and three failures, or near misses, at sea.
But Sunday's landing try, like the ones that preceded it, was a strictly secondary objective. The primary goal of the launch was to boost the Jason-3 satellite into orbit for NASA, the National Oceanic and Atmospheric Administration, the French space agency CNES and EUMETSAT, the European agency that manages weather satellite data.
Jason-3 is the fourth in a series of satellites that use state-of-the-art radar altimeters to measure the distance to the ocean surface below with extraordinary accuracy, allowing researchers to calculate ocean elevation, deep ocean temperatures, the velocity of currents, wave height and wind speed.
Jason-3 is "designed expressly for monitoring sea level rise, one of the clearest symptoms of global warming," said Laury Miller, NOAA's Jason-3 program scientist.
"It's now generally understood we've entered into a new era, a new norm, marked by rapid and persistent changes to the entire whole Earth system. What may not be widely understood is the role of the ocean in this complex process. More than 90 percent of all the heat now being trapped in the Earth system due to the greenhouse effect is actually going into the ocean.
"This makes the ocean perhaps the biggest player in the climate change story," he said. "Jason allows us to get the big picture in terms of sea level change in the years to come."
Jason-3's instruments also will collect data helping weather researchers and forecasters improve modeling of extreme weather, from hurricanes to tropical storms.
"In terms of severe weather, you don't have to look very far to find examples," Miller said. "Heavy rainfall, flooding, tornadoes out of season, droughts, all of these might seem like separate, isolated events, but many, if not all, of these are actually connected, linked to changes in the ocean occurring half a world away. The massive, turbo-charged El Nino that's currently battering the U.S. is perhaps one of the best examples."
Data from Jason-3 and its predecessors are "incredibly useful, especially to NOAA," Miller said, "because it allows us to not only track the sea level change that is impacting our coastal features right now but also to help forecast extreme weather."
Flying through heavy fog, the Falcon 9 climbed away from Space Launch Complex 4 at Vandenberg, on the California coast northwest of Los Angeles, at 1:42:18 p.m. EST (GMT-5; 10:42 a.m. local time), arcing away to the south toward a steeply inclined orbit around Earth's poles.
The Falcon 9's nine Merlin 1D first-stage engines shut down about two-and-a-half-minutes after launch and the single engine powering the rocket's second stage ignited for the first of two "burns" to continue the boost to orbit. A 12-second burn 55 minutes into flight finished the job, putting Jason-3 into its planned preliminary orbit.
Over the next 17 days, Jason-3 will be maneuvered into an nearly identical orbit with Jason-2, launched in 2008. Both spacecraft will fly over the same points, at the same time, allowing engineers to precisely calibrate Jason-3's instruments so its data are consistent with Jason-2's.
After about six months of flying in tandem, Jason-2 will be moved to a different orbital slot to improve global coverage.
"Jason-3, much like its predecessor Jason-2, will be able to measure the height of the ocean in an area that's about six miles across from 800 miles up with an accuracy of about one inch, so about the width of a quarter," said Josh Willis, Jason-3 project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"It's really quite an amazing feat. And if you average the data from one of these cycles of the Jason-3 or Jason-2 missions, you can actually get an accuracy for the levels of the oceans as a whole to better than half a centimeter, so really small. So we can really see the rise of the global oceans."
Since NOAA's first ocean altimetry mission in 1992 -- Topex/Poseidon -- and the first two follow-on Jason missions, global sea level has risen by about three millimeters per year, or about 2.8 inches over the past 23 years. It is expected to increase more rapidly in the years ahead.
"This is one of the most important yardsticks we have for human-caused climate change," Willis said. "With all the extra heat that's being absorbed by the oceans, the waters are expanding and of course, they are collecting the extra runoff from melting glaciers and ice sheets, which are also reacting to the warming climate.
"So these two things together cause global sea levels to rise. And in fact, that global rise is really our most powerful tool for measuring human-caused climate change."
Jason-3 is an international project with $177 million in funding from NOAA, which pays NASA for launch services, $119 million from EUMETSAT, the European Organization for the Exploitation of Meteorological Satellites, and $68 million from the French space agency CNES.