Deimos and Phobos Interior Explorer Center (DLR) and a study team with representatives of the scientific community and the space industry. The mission would explore the origin and the evolution of the two Martian moons, and would also contribute to the general questions of planetary formation and the workings of the Solar System. The origin of the Martian moons is controversial. Phobos and Deimos both have much in common with carbonaceous C-type asteroids, with spectra, albedo, and density very similar to those of C- or D-type asteroids. Based on their similarity, one hypothesis is that both moons may be captured main-belt asteroids. Another hypothesis is
Two Is Better Than One the top 40. It is also the group's biggest hit to date. By December 2011, "Two Is Better Than One" had sold 1,508,000 copies in the U.S. alone, outselling even other big Taylor Swift hits such as "Tim McGraw" and "Fifteen". As of November 2017, the song has sold 1.7 million copies in the United States. With both related artists receiving acclaim, the song became Boys Like Girls' second consecutive top 40 single on the "Billboard" Hot 100. Also, it gave Swift her twenty-first top 40 song on that chart. For the week of January 9, 2010, the song became