Taken by astronaut William Anders from the Apollo 8 spacecraft, this December 1968 photo of Earth rising over the lunar surface would become one of the most famous images of the 20th century. Credit: NASA

NASA heads into 2010 with the bittersweet assignment of retiring the space shuttle after nearly three decades. But that’s not all the agency has planned: There are also launches of three new satellites aimed at better understanding the Earth’s climate and oceans, and the sun.

Two of the probes will examine Earth — specifically the concentration of salt in the world’s oceans and the presence of aerosol particles, such as soot, in the atmosphere. A third mission will study the sun and its effect on space weather including solar flares that can disrupt communication on Earth.

All three come at a critical time for NASA. Data from the two Earth probes will likely influence global-warming research, and the trio of launches could serve as bright spots in a year otherwise dominated by debate over the future of the agency’s manned space program.

“They are extraordinary timely,” said Michael Freilich, head of NASA’s Earth-science division, of the two Earth probes. “It is a quest for understanding of the Earth system and [to improve] our ability to predict how our wonderful environment and our planet is going to change in the future.”

Combined, the three missions will cost more than $1.5 billion.

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