CAPE CANAVERAL – Two NASA science missions, one to Mars and the other to a pair of asteroids, remain on schedule for mid-summer launches.

The Delta II rocket that will carry the Dawn spacecraft to the asteroid belt went to the booster processing facility Wednesday, where it will be fitted with the explosives that will destroy the rocket if it flies off course and threatens a populated area.

The Dawn mission is set to blast off June 30, United Launch Alliance manager of launch operations Larry Penepent said Wednesday.

"We're scheduled to transfer this today, and we've transferred it today," Penepent said.

Dawn will visit two of the solar system's largest asteroids, which have remained intact since they formed. Ceres and Vesta are in the asteroid belt between Mars and Jupiter. They evolved very differently and could provide clues to the formation of our solar system.

Meanwhile, Phoenix is scheduled to launch Aug. 3 on a mission to an ice-rich region on Mars' north pole.

Technicians on Wednesday tested the engine control systems. With a robotic arm, Phoenix will search for water and evidence of conditions that could support life.

Additionally, an Air Force global positioning system satellite is scheduled to launch on another Delta II rocket as early as the end of August.

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