A European satellite built to monitor trends in polar ice will be grounded for up to a week because of an issue with the steering system on its Dnepr launcher.

Inside the Dnepr rocket's space head module, CryoSat 2 is loaded aboard a transporter earlier to ship to the launch silo earlier this week. Credit: ESA/Cyril Soulez-Lariviere

The CryoSat 2 satellite was supposed to launch Feb. 25 at 1357 GMT (8:57 a.m. EST) on a converted Ukrainian SS-18 ballistic missile from an underground silo at the Baikonur Cosmodrome in Kazakhstan.

In a statement released Friday, the European Space Agency blamed the delay on the steering system of the Dnepr rocket's second stage.

"Although the fuel supply of the second stage engine should be sufficient to get CryoSat into orbit, the fuel reserve is not as large as they would like it to be, according to the Ukrainian company Yuzhnoye, who developed and is responsible for the launcher," the ESA statement said.

Engineers are still reviewing the situation, and "measures will be taken to resolve this concern," according to ESA.

The Dnepr second stage is unmodified from the system used on the SS-18 ballistic missile, according to Kosmotras, the joint Russian-Ukrainian company that manages commercial flights of the booster.

Mission officials did not announce a new target launch date, although the delay is expected to be at least a week. Kosmotras will inform of ESA of a new date shortly, according to the statement.

Shrouded inside the booster's nose cone, the 1,587-pound spacecraft was transported to the Dnepr silo on Monday to be bolted to the 111-foot-tall rocket.

Artist's concept of CryoSat 2's separation from the Dnepr rocket in orbit. Credit: ESA

The $189 million mission will measure the precise thickness of land and sea ice with an Italian synthetic aperture radar altimeter system. The instrument will be able to determine ice thickness with a precision of less than an inch.

CryoSat 2 will replace a satellite destroyed in a launch mishap in October 2005. ESA chartered an almost identical spacecraft, added a few instrument upgrades, and selected a new rocket to launch the satellite.

The craft will circle Earth at an altitude of 435 miles, passing over latitudes as high as 88 degrees in the north and south polar regions. In such an orbit, CryoSat 2 will peer down on Arctic Ocean sea ice and land ice sheets covering Antarctica and Greenland.

Scientists expect CryoSat 2 will shed light on how fast ice coverage is diminishing and determine the overall mass of ice, which is critical for predicting sea level rise.