And with the exception of a single, two-week high activity period that begins on May 20th, the spacecraft is running on its own, and doing little besides checking into report status each Monday and to deliver a brief telemetry report most Thursdays. These contacts have shown that things are going well: all of the weekly status reports (technically called "beacon tones") have been green, and all of the telemetry passes have shown that the spacecraft is performing well.

Although our spacecraft has been hibernating, our ground and science teams have not been quiescent at all.

Planning for the Pluto encounter is in full swing now, with the goal of completing all of the near encounter sequence design and testing within about a year, so that we can conduct a full scale rehearsal on New Horizons in mid-2009. In fact, just this week we completed a formal review called the Encounter Requirements Review.

This review's purpose was to verify that, before we begin designing the detailed encounter sequences, we have in hand a fully complete list of every scientific and navigation activity that we plan to conduct during the encounter.

In June we will conduct our formal Encounter Feasibility Review, in which detailed encounter plans will be tested against dozens of ground and spacecraft constraints such as power, data storage, and available fuel, to ensure that every aspect of the developing encounter plan is fully feasible.

That review will be followed in August with a full up Preliminary Design Review (PDR) for the encounter, after which detailed sequence building will get underway. July of 2015 may be seven years away on the wall clock, but with our need to reduce our team size and budget after 2009, New Horizons must complete its encounter planning, ground testing, and a full dress rehearsal on the spacecraft barely more than one year from now!

The New Horizons ground team is also busy with sequence planning for this fall's spacecraft and instrument checkout period, which will run from September 2nd through mid-November.

In addition to the annual series of tests, this fall's activities will also include the uplink of new command and data handling, guidance/navigation, and fault protection software that resolves several dozen minor bugs and provides some new capabilities that will improve our ability to perform at Pluto and in the Kuiper Belt.

The ground team is also completing the build and beginning to test "NHOPS II," our second (and long desired) backup New Horizons spacecraft simulator, which will be operational at the Applied Physics Lab (APL) by late summer.

I mentioned that we plan to wake up New Horizons for a couple of weeks beginning on May 20th. The primary purpose of this wakeup is to re-point our spacecraft antenna to account for the motion of the Earth around the Sun. We have to conduct such re-pointings a number of times each year, and we use these as opportunities to group together important activities that need to occur between annual checkouts.

In the upcoming wakeup, spacecraft activities will include navigation ranging tests that mimic Pluto operations, spacecraft tracking, the downlink of accumulated impact data that the SDC dust counter instrument has collected so far this year, a bug fix software load and subsequent test of the SWAP solar wind plasma instrument, and an upload of the spacecraft command sequence that will take it from 3 June to 5 September.

The last thing I'll mention is this update is that our project secretary, JoAnne Kierzkowski, retired a couple of weeks ago. JoAnne worked at APL for many years, and came to the New Horizons project at the start-when the team formed in December 2000.

JoAnne provided expert project coordination to us, from the start of our proposal writing, through spacecraft design, build, test, launch and the first 1.5 billion kilometers of travel on the road to Pluto. Although she isn't going far and will be celebrating with us at the Pluto encounter in 2015, we will miss her work and her cheerful smile every day in between.

Well, that catches you up with where New Horizons is and what the spacecraft and project team have been doing. I'll be back with more news soon. In the meantime, keep on exploring, just like we do!

Alan Stern is principal investigator for New Horizons.

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