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Speeding to Zeus
February 21, 2007

We're a week from Jupiter closest approach. And if you're monitoring the "Where Is New Horizons?" page, you've likely noticed that we're already accelerating because of Jupiter's gravity. Although the effect is relatively small now, it will build dramatically in the coming days, giving us a boost of approximately 9,000 miles per hour (nearly 14,500 kilometers per hours) by the middle of next week. That's half the speed of a space shuttle in Earth orbit — essentially for free!

Meanwhile, the New Horizons spacecraft and payload are still performing well. As is the case most weeks, no unexpected events occurred; further, all of the Jupiter observations have been conducted just as planned. Additionally, continued tracking data shows us right on course to the "Pluto keyhole" - the spot near Jupiter we have to hit to remain on target to Pluto.

This is the last week of the low-intensity observation period before the Jovian onslaught that begins this Saturday, February 24. The highlight of this coming week for me is a pair of observations by our Alice ultraviolet spectrometer, which will observe a stellar occultation of Jupiter on Thursday, probing its upper atmospheric temperature and density profile.

This was New Horizons' last full-planet view of Jupiter, taken February 10. Now we're going in for a much closer look.

Next week the pace of operations reaches its crescendo near Jupiter, with some 15-20 observation sequences each day. We'll observe Jupiter, its rings, its moons and its magnetosphere. Also next week, the New Horizons Science Team will meet to plan the data analysis activities to come, and to begin planning (already!) for our Pluto encounter. Sure the Pluto system is eight years away, but when I watched a movie last weekend on TV from 1999, I realized that eight years seemed like yesterday. So onward we go — it's a long but worthy haul to the frontier that is the Kuiper Belt.

I'll be back with more news and views next week. Keep exploring!

- Alan Stern

During the Jupiter encounter, you'll also be able to read Alan Stern's blog on the Astronomy magazine Web site; check out for details.