A high-powered radar on a Nasa satellite designed to improve flood forecasting and monitor climate change has failed.
The key instrument, capable of collecting data from swathes of land as compact as 3km across, failed in July after less than three months in operation, NASA said, though the cause of the failure is currently unknown.
The $1bn (£657m) Soil Moisture Active Passive (SMAP) satellite was designed to spend at least three years in orbit taking measurements on the amount of water in the upper 5cm of the Earth's soil, but while its second instrument remains operational the level of detail it is capable of is far more limited.
"The project will do all it can to meet the expectations of the science community," lead researcher Dara Entekhabi, a professor at the Massachusetts Institute of Technology, told Reuters in an email.
Nasa had hoped to combine SMAP's high-resolution measurements with data from the lower-resolution instrument to get a better understanding of how much water, ice and slush is in the planet's top soil, but Entekhabi said scientists would rely on advanced data processing, coupled with other data from the mission, to help fill in gaps.
"What I will miss most about the SMAP radar is the opportunity for chance discovery. It was unique among the other instruments in orbit now because it provided frequent microwave mapping of the Earth's surface," he said.
Efforts to troubleshoot the problem were not successful and NASA this week declared the radar system failed.
Currently, scientists estimate soil moisture using computer modelling, but getting an accurate reading would be hugely helpful to scientists as the less than one per cent of the planet's total water locked into soil links Earth's environmental systems - its water, energy and carbon cycles - as well as determining whether particular regions are afflicted with drought or flooding.
"It's the metabolism of the system," Entekhabi told reporters before SMAP's launch in January.