Collis, a third-grader from Scottsdale, Arizona, was born in Siberia and had been adopted by an America family at the age two. Her submissions were selected from 10,000 entries.

"She has in her heritage and upbringing the soul of two great spacefaring countries, to be sure," O'Keefe said. "We have names for these rovers that are extremely worthy of the bold mission they are about to undertake."

The names are based on the feelings Collis said she experienced when she first learned she was coming to America.

"I used to live in an orphanage. It was dark and cold and lonely. At night I looked up at the sparkly sky. I felt better. I think I could fly there. In America I can make all my dreams come true. Thank you for the spirit and the opportunity," she said.

The Name the Rovers contest was open for K-12 American students. Essays justifying the name selections ranged in length from 50 words to 500 words depending on the grade level.

"Sofi wrote a moving essay that caught many people's attention in the judging process," Planetary Society Director of Projects Bruce Betts said on the society's website. "Thousands got involved in Mars Exploration through this process. The icing on the cake is that Sofi and her family are absolutely charming."

The Planetary Society also ran naming contests for Mars Pathfinder's Sojourner Truth rover, and the Magellan spacecraft.

A heavy line of thunderstorms moving toward the launch site prompted NASA to call off Sunday's attempt to send the Mars Exploration Rover-A, now dubbed Spirit, toward the Red Planet. They will attempt to launch on Monday, June 9.

Mars Exploration Rover-B, now called Opportunity, is scheduled to launch on June 25.