Mars 98 Mission Status Report May 21, 1999

The Mars Climate Orbiter and Mars Polar Lander spacecraft thattogether make up NASA's Mars Surveyor '98 mission are now midway in theirlong journey to Mars. Mars Climate Orbiter is nearly two-thirds of itsway to Mars, having traveled about 413 million kilometers (257 millionmiles) since its launch on December 11, and has 255 million kilometers(158 million miles) yet to go.

Mars Polar Lander is almost at the halfwaypoint of its journey having logged 360 million kilometers (224 millionmiles) since launch on January 3, with 398 million kilometers (247 millionmiles) to go. The two spacecraft are in excellent health and operating essentially under automatic control as they proceed through space underthe influence of the Sun's gravitational pull. So far, each spacecraft hasfollowed a course that closely parallel's Earth's orbit around the Sun.Today, Mars Climate Orbiter is 55 million kilometers (34 million miles)from Earth, and Mars Polar Lander is 39 million kilometers (24 millionmiles) away, even though they have both traveled hundreds of millions of kilometers. This is typical of interplanetary spacecraft that followflight paths that spiral slowly toward or away from the Sun, whiletraversing much larger distances around it. During the second half oftheir trip, the two spacecraft will appear to accelerate rapidly away from Earth as they spiral outward toward the orbit of Mars.