Japan's Advanced Land Observing Satellite, one of the world's foremost remote sensing platforms, inexplicably lost power Friday, likely ending its mission mapping Earth and monitoring natural disasters, according to the Japan Aerospace Exploration Agency.

Artist's concept of ALOS in space. Credit: JAXA
 
The spacecraft switched to a low-power mode around 7:30 a.m. Japan time Friday (2230 GMT Thursday), where the satellite's three observation instruments shut down to conserve electricity.

Telemetry indicated ALOS lost all power later Friday, according to JAXA.

"Since then, the power generation has been rapidly deteriorating, and we currently cannot confirm power generation," a JAXA press release said.

Nicknamed Daichi, the Japanese word for land, ALOS launched aboard an H-2A rocket Jan. 24, 2006. The satellite unfurled a 72-foot-long solar panel, the largest single deployable array on any Japanese spacecraft. It was designed to produce at least 4 kilowatts of power at the end of the satellite's life.

The ALOS mission was supposed to last at least three years, and the craft narrowly achieved JAXA's stated goal of five years of operations.

"JAXA is investigating the cause of this phenomenon while taking necessary measures," the statement said.

Two other electrical system failures have ended major Japanese satellite observation missions in the last 15 years.

The ALOS anomaly signature is similar to the failure of the Advanced Earth Observing Satellite 2, or ADEOS 2, which lost electricity in October 2003 and was never heard from again.

ADEOS 2 replaced another satellite that succumbed to structural damage on its solar panel less than a year after it launched.

JAXA did not announce what part of the power generation system could be at fault on ALOS, or if the declining electricity levels were a symptom of another issue.

ALOS captured this image with the AVNIR 2 radiometer instrument showing the flooded Sendai airport and other parts of Japan's Miyagi prefecture. Credit: JAXA
 
In its five-year mission, ALOS mapped the Earth's surface, created three-dimensional terrain models, snapped thousands of pictures and observed the aftermath of earthquakes, volcanos, hurricanes and the March 11 tsunami that ravaged Japan.

ALOS imagery showed Japan's inundated northeast coastline in the days after the tsunami, and its radar instrument detected parts of the Japanese island of Honshu were displaced by up to 10 feet by the 9.0-magnitude earthquake that spawned the tsunami.

The spacecraft's three payloads included PRISM, a stereo mapping imager to derive 3D elevation maps with a resolution of 2.5 meters, or 8.2 feet. AVNIR 2, an advanced visible and near-infrared radiometer, collected data on land use and vegetation. A synthetic aperture radar named PALSAR bounced radar signals off Earth's surface for day-and-night observations in all weather conditions.