Europe is preparing to launch a new satellite to unravel the mysteries of Earth's water cycle, shedding new light on how moisture is absorped into the atmosphere and the process's link to climate change.

Artist's concept of the Rockot launcher with SMOS. Credit: ESA

The Soil Moisture and Ocean Salinity, or SMOS, satellite is awaiting launch early Monday aboard a Rockot launcher. The Rockot, made of retired ballistic missile parts, will take off from Complex 133 at the Plesetsk Cosmodrome about 500 miles north of Moscow.

The European Space Agency and the French space agency, CNES, are leading the project to measure moisture levels in soil and salt quantities in the uppermost layers of the oceans. These factors play critical roles in the water cycle, determining how much water can be evaporated to fuel storms and the pattern of ocean currents across the globe.

"The importance of the mission is to provide measurements of soil moisture and ocean salinity, which are two very dominant variables in the water cycle," said Susanne Mecklenburg, SMOS mission manager.

"Thus, we will be able to actually improve our knowledge of our water and energy cycles on the Earth, which will also support us in understanding better how the Earth system actually works and also corresponds to present changes in the Earth climate," Mecklenburg said.

SMOS is the first satellite designed to directly study soil moisture and ocean salinity, according to scientists.

Liftoff is scheduled for 0150:51 GMT Monday (8:50:51 p.m. EST Sunday), or in the predawn hours at Plesetsk.

The Rockot will fly north from Plesetsk, shedding its first two stages and protective payload shround within five minutes. The launcher will pass out of range of Russian communications stations a few minutes after launch, leaving engineers on the ground with no insight on the mission's progress.

"We leave the coverage of the Russian tracking system. So as of then, we are basically blind," said Achim Hahne, SMOS project manager. "The only thing we can verify is the separation itself by our satellite downlinking down the telemetry on its own once it is separated."

Artist's concept of the SMOS satellite with deployed solar arrays and instruments. Credit: ESA

The Breeze KM upper stage will take over for two major engine firings, first to propel the the rocket to a temporary parking orbit, then to hone in on a trajectory to deploy the SMOS payload.

The Breeze upper stage is aiming for an orbit ranging in altitude from 465 miles to 476 miles, with an inclination to the equator of about 98.4 degrees.

The rocket will release SMOS at 0300 GMT (10 p.m. EST) as it flies just south of Madagascar.

A few minutes later, officials will receive the first signals from the satellite since shortly after launch.

"The next signal we get is a station in South Africa, which is called Hartebeesthoek," Hahne said.

By that time, SMOS should be executing a programmed series of events to activate the 1,451-pound spacecraft, including unfurling its two solar panels for electricity.

"The separation itself will trigger on the satellite an automatic sequence, which means that within three minutes we will deploy the solar arrays on the satellite," Hahne said.

"We can say the satellite is in a safe state because it has acquired some pointing attitude by then. The solar arrays are out so the batteries can be charged," Hahne said. "There is power for thermal control, and basically what we do is wait for thermal stabilization and so on, but we could stay for a long time in this status."

The Breeze third stage will fire its small steering thruster system twice over the next hour to reach a circular orbit 449 miles high. The rocket will jettison part of a conical adapter to expose ESA's Proba 2 satellite, a 287-pound secondary payload designed to test new space technologies.

Proba 2 will be deployed at 0450 GMT (11:50 p.m. EST).

Artist's concept of Proba 2 separating from the Breeze KM upper stage. Credit: ESA

"This Proba satellite has an automatic sequence and once it is released it starts doing it's own things like deploying its solar array and getting in contact with Redu, which is a Belgian ground station, in order to dump down data saying, 'look, I have deployed and am in a safe state.'"

SMOS will deploy the three Y-shaped arms of its L-band radiometer instrument Tuesday, beginning a six-month commissioning phase to verify the integrity of the payload and calibrate data.

The satellite's instrument, called MIRAS, includes 69 individual antennas to create an array of sensors to provide high resolution data that would normally require a much larger spacecraft.

Engineers hope to have the MIRAS payload fully activated within two weeks to begin testing.

Thales Alenia Space built the SMOS spacecraft and the high-tech instrument was manufactured by EADS CASA in Spain.

SMOS will operate for at least two-and-a-half years in ESA's fleet of small Earth Explorers. The mission could last much longer, if funding is available, according to Hahne.