NASA’s Cassini spacecraft burns up in skies over Saturn

In this March 26, 1997 file photo, a technician checks the heat shield of the space probe Huygens in the cleanroom of Dornier Satellitensysteme GmbH in Ottobrunn, Germany, near Munich. The probe will be carried by NASA's Cassini orbiter and is designed to explore Saturn's moon Titan. (AP Photo/Uwe Lein)
Updated 15 September 2017
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NASA’s Cassini spacecraft burns up in skies over Saturn

CAPE CANAVERAL, Florida: NASA’s Cassini spacecraft disintegrated in the skies above Saturn early Friday in a final, fateful blaze of cosmic glory, following a remarkable journey of 20 years.
Confirmation of Cassini’s expected demise came about 7:55 a.m. EDT. That’s when radio signals from the spacecraft — its last scientific gifts to Earth — came to an abrupt halt. The radio waves went flat, and the spacecraft fell silent.
Cassini actually burned up like a meteor 83 minutes earlier as it dove through Saturn’s atmosphere, becoming one with the giant gas planet it set out in 1997 to explore. But it took that long for the news to reach Earth a billion miles away.
The only spacecraft to ever orbit Saturn, Cassini showed us the planet, its rings and moons up close in all their splendor. Perhaps most tantalizing, ocean worlds were unveiled on the moons Enceladus and Titan, which could possibly harbor life.
Dutiful to the end, the Cassini snapped its “last memento photos” Thursday and sampled Saturn’s atmosphere Friday morning as it made its final plunge.
Program manager Earl Maize made the official pronouncement:
“This has been an incredible mission, an incredible spacecraft and you’re all an incredible team,” Maize said. “I’ll call this the end of mission.”
Flight controllers wearing matching purple shirts stood and embraced and shook hands.
More than 1,500 people, many of them past and present team members, had gathered at California’s Jet Propulsion Laboratory for what was described as both a vigil and celebration. Even more congregated at nearby California Institute of Technology, which runs the lab for NASA.

NASA’s science mission director, Thomas Zurbuchen, made note of all the tissues inside JPL’s Mission Control, along with the customary lucky peanuts. Team members were clearly emotional, he said.
“These worlds that they found, we never knew were there, are changing how we think about life itself,” he said. “And so for me, that’s why it’s truly a civilization-scale mission, one that will stand out among other missions, anywhere.”
Project scientist Linda Spilker noted Cassini has been running “a marathon of scientific discovery” for 13 years at Saturn.
“So we’re here today to cheer as Cassini finishes that race,” she said.
The spacecraft tumbled out of control while plummeting at more than 76,000 mph (122,000 kph). Project officials invited ground telescopes to look for Cassini’s last-gasp flash, but weren’t hopeful it would be spotted against the vast backdrop of the solar system’s second biggest planet.
This Grand Finale, as NASA called it, came about as Cassini’s fuel tank started getting low after 13 years exploring the planet. Scientists wanted to prevent Cassini from crashing into Enceladus or Titan — and contaminating those pristine worlds. And so in April, Cassini was directed into the previously unexplored gap between Saturn’s cloud tops and the rings. Twenty-two times, Cassini entered the gap and came out again. The last time was last week.
The leader of Cassini’s imaging team, Carolyn Porco, a visiting scholar at the University of California, Berkeley, was so involved with the mission for so long that now, “I consider it the start of life, part two.”
Cassini departed Earth in 1997 and arrived at the sixth planet from our sun in 2004. The hitchhiking European Huygens landed on big moon Titan in 2005. Nothing from Earth has landed farther. Three other spacecraft previously flew past Saturn, but Cassini was the only one to actually circle the planet.
In all, Cassini collected more than 453,000 images and traveled 4.9 billion miles. It was an international endeavor, with 27 nations taking part. The final price tag was $3.9 billion.
European space officials joined their US colleagues to bid Cassini farewell.
“It’s a very historical moment,” said the Italian Space Agency’s president, Roberto Battiston.
There were lighthearted touches as well. During its broadcast NASA played a video clip of the Cassini Virtual Singers, spacecraft team members who belted out, “Tonight, tonight, we take the plunge tonight ...” to the music from “West Side Story.”
Scientists are already eager to go back and delve into the wet, wild worlds of Enceladus and Titan. Proposals are under consideration by NASA, but there’s nothing official yet. In the meantime, NASA plans sometime in the 2020s to send an orbiter and lander to Europa, a moon of Jupiter believed to have a global ocean that might be compatible for life.
“Yes, we really want to go back” to Saturn, Zurbuchen said. “It’s such a wonderful system, we don’t want to leave it alone.”


Thaw of Antarctic ice lifts up land, might slow sea level rise

Updated 22 June 2018
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Thaw of Antarctic ice lifts up land, might slow sea level rise

  • The fast rise of the bedrock beneath will lift ever more of the ice onto land, reducing the risks of a breakup of the sheet caused by warming ocean water seeping beneath the ice
  • The process was too slow to save the ice sheet from a possible collapse triggered by global warming

OSLO: Antarctica’s bedrock is rising surprisingly fast as a vast mass of ice melts into the oceans, a trend that might slow an ascent in sea levels caused by global warming, scientists said on Thursday.
The Earth’s crust in West Antarctica is rising by up to 4.1 centimeters (1.61 inches) a year, an international team wrote in the journal Science, in a continental-scale version of a foam mattress reforming after someone sitting on it gets up.
The rate, among the fastest ever recorded, is likely to accelerate and could total 8 meters (26.25 feet) this century, they said, helping to stabilize the ice and brake a rise in sea levels that threatens coasts from Bangladesh to Florida.
“It’s good news for Antarctica,” lead author Valentina Barletta of the Technical University of Denmark and Ohio State University told Reuters of the findings, based on GPS sensors placed on bedrock around the Amundsen Sea in West Antarctica.
Much of the West Antarctic ice sheet, which has enough ice to raise world sea levels by more than three meters (10 feet) if it ever all melted, rests on the seabed, pinned down by the weight of ice above.
The fast rise of the bedrock beneath will lift ever more of the ice onto land, reducing the risks of a breakup of the sheet caused by warming ocean water seeping beneath the ice.
The uplift “increases the potential stability of the West Antarctic Ice Sheet against catastrophic collapse,” the scientists wrote.
Last week, another study said that three trillion tons of ice had thawed off from Antarctica since 1992, raising sea levels by almost a centimeter — a worsening trend.
It often takes thousands of years for the Earth’s crust to reshape after a loss of ice. Parts of Scandinavia or Alaska, for instance, are still rising since the end of the last Ice Age removed a blanket of ice more than a kilometer thick.
A further report this month found that the West Antarctic ice sheet expanded about 10,000 years ago, interrupting a long-term retreat after the last Ice Age, because of a rise of the land beneath.
But it said the process was too slow to save the ice sheet from a possible collapse triggered by global warming.
One of the lead authors of that study, Torsten Albrecht at the Potsdam Institute for Climate Impact Research, told Reuters on Thursday: “The expected eight-meter (26.4-foot) uplift in 100 years in the Amundsen Sea region ... seems rather small in order to prohibit future collapse.”