http://pluto.jhuapl.edu/news_center/news/040706.htm
Outbound for the Frontier, New Horizons Crosses the Orbit of Mars
April 7, 2006
New Horizons’ trailblazing journey to the solar system’s outermost
frontier took it past the orbit of Mars today at 6 a.m. EDT (1000 UTC),
78 days after the spacecraft launched.
At the time, because of Mars’ position in its orbit, New Horizons was
actually closer to Earth than to Mars - just 93.5 million kilometers
(58.1 million miles) from home, compared to 299 million kilometers (186
million miles) from the red planet. Speeding away from the Sun at 21
kilometers (about 13 miles) per second, the spacecraft crossed Mars’
path some 243 million kilometers (151 million miles) from the Sun -
close to the farthest point in Mars’ elliptical 687-day orbit.
New Horizons reaches its next planetary milestone on February 28, 2007,
when it makes its closest approach to Jupiter. Unlike the distant Mars
passing today, the Jupiter encounter will be at close range, allowing
New Horizons to make important scientific observations and to test
procedures for its Pluto encounter in 2015. Additionally, New Horizons
will use Jupiter’s powerful gravity to boost its speed and adjust its
course toward Pluto and the Kuiper Belt.