The US space agency said it is sending a team of scientists on the second and final mission of a Nasa field study of how melting Arctic ice is changing the life cycles of sea creatures.
The five-week mission, which kicks off on Saturday, focuses on tiny organisms called phytoplankton, whose population blooms can offer clues about the wider health of the ocean ecosystem and how a warming climate may change the ocean’s ability to absorb carbon from the atmosphere.
Phytoplankton blooms in the Arctic have been observed to peak as many as 50 days earlier than they did a dozen years ago, a development that could have implications for the larger food web, scientists have said.
The microscopic organisms are the base of the food chain and drive the food and reproductive cycles of fish, seabirds and polar bears. How larger animals may react to phytoplankton changes remains unknown.
The mission, known formally as Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment, or Icecape, combines satellite data with on-site measurements of the Chukchi and Beaufort seas along Alaska’s coast.
“Last year, Icecape nailed down quite a few things in terms of the phytoplankton work,” said chief scientist Kevin Arrigo of Stanford University in Palo Alto, California.
“We know pretty well now how fast they are growing and what they are responding to. The repeat measurements from this voyage will help us confirm what’s going on.”
Nasa said this year’s mission begins about three weeks later than it did last year, meaning that the Healy icebreaker should be able to better navigate the thinner, summer ice and explore the ecosystem.
Between 2004 and 2008, “multi-year ice cover shrank 1.5 million square kilometres – nearly the size of Alaska’s land area,” said a 2009 report of the findings from Nasa’s Ice, Cloud and Land Satellite.
From 2003 to 2009, the ICESat mission provided multi-year elevation data needed to determine ice sheet mass balance as well as cloud property information, especially for stratospheric clouds common over polar areas.
It also provided topography and vegetation data around the globe, in addition to the polar-specific coverage over the Greenland and Antarctic ice sheets.
Last August the Ice, Cloud, and Land Elevation Satellite was successfully decommissioned from operations.
As part of the final stage of mission decommissioning, the flight operations team passivated the spacecraft in compliance with Nasa policy and regulations that seek to “minimise the creation of orbital debris by government and non-government operations in space in order to preserve the space environment for future generations”.
To passivate ICESat, the team sent and activated a series of commands previously stored in the on-board computer to remove all forms of stored energy from the spacecraft.
The team verified successful passivation after confirming negative acquisition of signal by ground network tracking stations. Re-entry information will be issued by the Nasa Orbital Debris Program Office from data provided by the US Space Surveillance Network.