DARMSTADT, Germany —Europe’s CryoSat-2 polar-ice-monitoring Earth observation satellite was successfully launched April 8 aboard a Russian-Ukrainian Dnepr rocket and is expected to undergo a six-month checkout period before starting three years of radar observations this fall.

Operating from Russia’s Baikonur Cosmodrome in Kazakhstan, the Dnepr silo-launched rocket — a converted SS-18 ballistic missile marketed by Kosmotras of Moscow — placed the 720-kilogram CryoSat-2 satellite into a 720-kilometer near-polar orbit inclined at 92 degrees relative to the equator.

A European Space Agency (ESA) ground tracking station in Malindi, Kenya, confirmed the satellite’s successful separation from the rocket and initial in-orbit health.

The launch, which came four-and-one-half years after the original CryoSat satellite was destroyed in a launch failure of a Russian Rockot vehicle, followed months of delays related to the availability of Dnepr.

The launch had also been delayed because of a last-minute concern that Dnepr would not be able to carry CryoSat-2 to the intended altitude of 720 kilometers. That issue was resolved when Dnepr designers modified the fuel to the vehicle’s second-stage steering engines to permit the 720-kilometer orbit.

It was not only CryoSat-2’s weight that pushed Dnepr to its performance limit. At 4.6 meters in length, CryoSat-2 required Dnepr’s extended fairing, which meant that the rocket’s underground silo was left uncovered leading up to launch.

Taking account of the expense of the first satellite, the CryoSat mission will have cost the 18-member ESA about 254 million euros, or $339.4 million at current exchange rates. That figure includes 145 million euros for CryoSat-1 and 109 million euros needed to build CryoSat-2. The budget also includes three years of in-orbit operations.

Astrium Satellites of Friedrichshafen, Germany, built CryoSat-2 under a contract valued at 75 million euros. While the mission is scheduled to last for three years following the six-month checkout, the satellite’s fuel, batteries and other consumables are sufficient to last for at least five years, said Eckard Settelmeyer, director of Earth observation at Astrium Satellites.

CryoSat-2 is not an exact duplicate of the original CryoSat. Unlike the first version, CryoSat-2 features a backup Siral radar instrument, to be used in the event of a failure of the primary Siral, or SAR Interferometric Radar Altimeter.

Thales Alenia Space of France and Italy built Siral, which follows on a series of satellite radar altimeters including those flying on the U.S.-French Jason ocean-observing satellites.

ESA Earth Observation Director Volker Liebig said CryoSat-2’s ability to measure, with centimeter-level accuracy, the polar ice caps is of obvious environmental importance given that the caps contain an estimated 77 percent of Earth’s fresh water resources.

Some 10 percent of Earth’s land surface is permanently covered by ice, and one of CryoSat-2’s missions is to furnish data permitting better estimates of global warming and associated rises in sea levels.

But in a presentation made just before the launch, Liebig said that as the Arctic regions become more navigable with the reduction of ice coverage, the regions have a geopolitical interest as well for their suspected reserves of oil and gas.

Peter B. de Selding was the Paris bureau chief for SpaceNews.