Today, as the International Astronomical Union’s decision to reclassify Pluto as a ‘plutoid’ was announced, Hal Weaver, who is something of a Pluto expert, couldn’t be bothered. When I queried him, he emailed back in shorthand Blackberry fashion to say that he was in a “very important meeting.”

Later, Weaver called to say the meeting was to plan for a rehearsal next summer for the Pluto-bound New Horizons spacecraft, which Weaver says will “completely revolutionize our understanding of the Pluto system.” (Perhaps then astronomers can finally agree on some definitions.)

It’s a rehearsal that was not part of the initial mission plan. But with seven years to go before the probe gets there, Weaver and his colleagues, led by Alan Stern, have decided not to twiddle their thumbs. They’re going to unfold the probe’s instruments next summer and put ‘em through the paces.

“We’re going to run all of the activities as we planned them and as we hope to run the real encounter,” said Weaver, a physicist at Johns Hopkins University Applied Physics Laboratory. So now they are working on the timeline and the details of the rehearsal.

The idea is to point the instruments in the same directions as they will in 2015. Pluto and its moons won’t be in the field of view, but the same star backgrounds will be, Weaver explained. So they should get a good idea of how everything works … or doesn’t. This will give the team “more leisure to make changes” based on any issues raised in rehearsal.

A dress rehearsal had always been planned for 2012, but after New Horizon’s recent Jupiter flyby, Weaver said, “we learned a lot about how to do it right.” They figure it’s smart to bump up the first rehearsal “while it’s still fresh in our minds.” Two or three other rehearsals will likely be done later.

Weaver said there’s been an explosion of knowledge about planets and other solar system objects in the past two decades.

“We shouldn’t get too hung up on definitions,” he said of the IAU’s “plutoid” plan. “We define categories to help us figure out the universe, to put things in boxes. But there are limitations to that kind of approach. Nature doesn’t necessarily fit our definitions. You’ll never have a perfect system.”

New Horizons crossed Saturn’s orbit on June 8. To get to Pluto, it will traverse 3 billion miles of space (5 billion km) over 9.5 years at about 27,000 mph (43,000 kph). Then it’ll come within 6,200 miles (10,000 km) of Pluto.

In our phone conversation, I mentioned how incredible it is that they can shoot a spacecraft clear across the solar system and actually arrive at the exact right place at the right time.

“It amazes me, too,” Weaver said, “that we can pull off these planetary flybys … most of the time.”

A lot of hard work is involved, he said, and of course, he added: “It’s all rocket science.”