Nozomi (のぞみ) (Japanese for "Wish" an known before launch as Planet-B) was planned as a Mars-orbiting aeronomy probe, but was unable to achieve Mars orbit due to electrical failures. It was constructed by the Institute of Space and Astronautical Science, University of Tokyo and launched on July 3, 1998 at 18:12:00 UTC with an on-orbit dry mass of 258 kg.