John SpencerJan 12, 2006

Looking Forward to New Horizons' Launch (12 January 2006)

New Horizons science team member John Spencer sent me another entry last night on the preparations for the approaching launch of New Horizons to Pluto. --ESL

This is probably my last missive before Jane and I leave for the Cape on Friday in preparation for the launch. Our pre-launch schedule includes a New Horizons Science Team meeting on Saturday 14th, the pre-launch party on Sunday, and our first shot at the actual launch on Tuesday afternoon -- the 2-hour window opens at 1:24 pm Eastern time. Adding to the excitement for me personally, my sister Frances will be flying in from England to join us for the festivities. From Saturday evening onwards there's also a continual series of media and public events -- I'll throw in a shameless plug here for my talk about Pluto and the mission at 7 pm on Saturday at the Brevard Community College planetarium near Kennedy Space Center, though as I write this, I see that they don't yet have a notice of the talk on their web site. There will also be public talks at Kennedy Space Center, featuring Andy Cheng on Sunday afternoon, Bill McKinnon on Monday afternoon, and Marc Buie on Tuesday morning, shortly before the launch. Having linked to my friends' web pages, I now have an excuse to include a link to my own: here it is.

We continue to plan for the Jupiter encounter, which (assuming we launch on February 2nd or before) occurs, astonishingly, a mere 13 months after launch. For comparison, it took Pioneer 10 21 months, and Voyager 1 18 months, to cover the same distance in the 1970s, while Galileo, being heavier and needing to arrive more slowly to get into orbit, followed a roundabout trajectory and took 6 years to get to Jupiter between 1989 and 1995.

Detailed planning of our observations of Jupiter and its satellites must wait till after we launch, because the launch date determines the Jupiter flyby date, and that in turn determines the orbital positions of the satellites during the flyby and the timing of many of our observations, including critical events like satellite eclipses by Jupiter. We're planning a team meeting in late February where we'll hash out the details, once the spacecraft is safely on its way and we know the geometry. The Jupiter plan will be a balancing act between many conflicting factors. We'll need to turn the main antenna to the Earth periodically to download data and track the spacecraft's trajectory (after all, the primary purpose of the Jupiter flyby is to speed us on our way to Pluto), but this will interrupt our observations, because all instruments are fixed on the spacecraft and pointing the antenna at Earth means not pointing the instruments at Jupiter. We'd love to make high resolution movies of Jupiter's turbulent storms, but our spacecraft data system is designed for the Pluto encounter, where we fly rapidly past a couple of relatively small targets and have months to play back the data, so we don't have the storage or downlink capacity for the enormous number of images we'd need to do full justice to Jupiter's hyperactive meteorology. And so on. We will do wonderful things at Jupiter, but we can't do everything, and we'll make our choices carefully.

In the meantime, we have another important date on the calendar -- proposals for time on the Hubble Space Telescope are due on January 27th. There are some things that Hubble can do better than New Horizons during the Jupiter flyby (for instance, New Horizons can take ultraviolet spectra of Jupiter's moons, but not images, while Hubble can take images, but not spectra). The combined efforts of the two spacecraft will thus tell us more than either can do on its own, and at our team meeting on Saturday we'll discuss how to make the most of this synergy, and finalize our plans to condense the potential Hubble science into pithy telescope proposals.

John will be sending me occasional updates on New Horizons throughout the launch, and I'll post them here. Thanks John! --ESL

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