Ebb and Flow are the new names of twin NASA spacecraft that orbited the moon on New Year's Eve and New Year's Day.

The names were among 890 submitted in a contest that invited ideas from U.S. students from five to 18 years old.

GradeĀ 4 students at Emily Dickinson Elementary School in Bozeman, Mont., had the winning entry.

The washing machine-sized spacecraft, previously named Gravity Recovery And Interior Laboratory, or GRAIL A and B, are to begin science operations in March. As they study the moon, they will undergo nearly the same motion as the tides we feel here on Earth.

The students hit the nail on the head in coming up with the names, said Maria Zuber, GRAIL principal investigator from the Massachusetts Institute of Technology.

"We were really impressed that the students drew theirĀ inspiration by researching GRAIL and its goal of measuring gravity. Ebb and Flow truly capture the spirit and excitement of our mission."

GRAIL is billed as NASA's first planetary mission carrying instruments fully dedicated to education and public outreach. Each spacecraft carries a small camera called GRAIL MoonKAM (Moon Knowledge Acquired by Middle school students).

Thousands of students in Grades 5 to 8 will select target areas on the lunar surface and send requests for study to the GRAIL MoonKAM Mission Operations Center in San Diego. The Dickinson students get to choose the first camera images.

Launched in September 2011, Ebb and Flow will be placed in a near-polar, near-circular orbit with an altitude of about 55 kilometres. During their science mission, the duo will answer longstanding questions about the moon and give scientists a better understanding of how Earth and other rocky planets in the solar system formed.