February 26, 2007Range to Jupiter: 0.03 astronomical unit (2.8 million miles; 4.5 million kilometers)
We're in the thick of it at Jupiter now! Since early Saturday, the 24th, New Horizons has been executing its Jupiter close approach sequence. This sequence contains 15 to 20 observations per day almost 10 times what we were doing just a week earlier.
Here on the ground, we aren't seeing much science data yet. But the engineering data we're getting shows the encounter is progressing according to plan (nominally, as we in the space business like to say), and the various observations are coming off right on schedule.
What's up next? Well today (Monday the 26th), we are studying the atmospheric composition and structure of Io and Callisto, mapping the surface compositions of Ganymede and Europa, imaging Io's volcanic plumes, searching for moonlets embedded in Jupiter's rings, obtaining ring images to study how its dust particles behave depending on phase angle, and taking high-resolution images of the Little Red Spot on Jupiter itself. We're also studying Jupiter's magnetosphere continuously and sending home 8 hours of downlink data. We reach closest approach late tomorrow, but not before we make twice as many observations as we did today!
Before I close for today, I've been asked recently to say something about what became of the now derelict Boeing STAR-48 upper stage, which boosted us onto our Jupiter trajectory. Well, the last anyone saw it was on launch day. As a result, we don't know its trajectory nearly as well as we do the path of New Horizons. We do know, however, that the upper stage will make its closest approach to Jupiter Tuesday (the 27th), approximately 6 hours before New Horizons does.
Moreover, we know the upper stage is headed to an aim point almost 300,000 miles (half a million km) farther from Jupiter than New Horizons. As a result of these "errors" in its trajectory, it will miss Pluto in 2015 by a wide berth about 120 million miles (200 million km) nearly as far as the distance between the Sun and Mars!
OK, that's it for now. I'll be back with more news and views later this week. Keep exploring, as we do!