Washington ? Scientists are reaching out this month to touch two heavenly bodies that have never before been visited by spaceships from Earth: the core of a passing comet and a moon orbiting a distant planet.

The goal is to learn more about the origin and evolution of the solar system, our homeland in the vastness of the universe.

Today, NASA is scheduled to launch its Deep Impact spacecraft from Cape Canaveral on its way to the comet Tempel 1, floating 83 million miles away between the planets Mars and Jupiter.

When it arrives July 4, the spaceship will drop an 820-pound slab of copper, hoping to punch a hole, perhaps as deep as a 10-story building, in the comet’s hidden nucleus.

The idea is to find out what’s inside those mysterious luminous objects that have fascinated — and frightened — humans for thousands of years. People used to think comets were ill omens of famine, flood or the deaths of kings. Now scientists think they contain the most primitive material left in our patch of the sky.

“Comets are the oldest bodies in the solar system,” said Andy Dantzler, the acting director of NASA’s solar system division. “They contain the oldest clues to answer fundamental questions: How did the solar system form? How did it evolve? How did life begin?”

Two days later, a European Space Agency lander called Huygens will parachute onto the surface of Saturn’s giant moon Titan. The wok-shaped lander will be “the furthest man-made object to land on a remote celestial body,” Ian Halliday, the British astronomer in charge of the mission, said in a statement from Scotland.

In this image released by the European Space Agency, in Darmstadt, Germany, this illustration shows the Huygens probe with parachute on its way through the clouds of the Saturn moon Titan. This part of the Huygens mission is planned for Friday.

Huygens was released from NASA’s Cassini satellite on Christmas Eve and is drifting above Titan until time for the landing. Cassini began orbiting Saturn, 885 million miles from the sun, last June after a six-year voyage, and has been observing its famous rings and many moons ever since.

Titan, larger than the planets Mercury and Pluto, fascinates scientists because its thick, nitrogen-rich atmosphere resembles conditions on Earth billions of years ago, before living organisms began enriching our air with oxygen.

Stuffed with 12 scientific instruments, Huygens will relay observations during its two-hour descent and for up to a half-hour after landing. Scientists aren’t sure whether it’ll splash into a sea of liquid methane, squelch into frozen mush or crash into solid ground.