Pluto and Planethood

Today NASA's "New Horizons" mission, launched just over 13 months ago, will fly past Jupiter on its way to Pluto. The giant planet will provide a gravitational boost to the spacecraft, helping it reach the edge of our solar system by 2015. Over the past few decades, NASA satellites have visited Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune -- but this is the first mission ever to visit Pluto. Meanwhile, astronomers have decided that Pluto should no longer be considered a planet.

To the average person, it probably seemed ridiculous when the International Astronomical Union announced last August that Pluto would henceforth be known as a "dwarf planet" -- the prototype of a new class of objects in the outer solar system. It even led to a satirical headline reading "NASA Launches Probe To Inform Pluto Of Demotion". However, there were legitimate scientific developments that compelled astronomers to adopt a new definition of planet -- it was just unfortunate that this new definition removed Pluto from the list.

Starting in 1992, astronomers began to discover many small icy objects outside the orbit of Neptune that appeared similar to comets, but which never came close enough to the Sun to evaporate and develop tails. As time went by and the technologies for detecting these objects improved, surveys began to identify some larger examples. In the last few years, astronomers found several that are comparable in size to Pluto -- and even one that is larger! Theories suggested that there were likely to be hundreds or thousands of such objects in the outer solar system, so classifying them all as new planets could create real problems for school children trying to remember them all.

Since Pluto appeared to be just one of the larger members of this class of objects, it fell victim to the new classification scheme. Like many political decisions, the available choices were limited to bad (define planet in a way that excludes Pluto) or worse (bestow the title of planet on hundreds of new objects). Conspicuously absent was an alternative proposal to adopt a new definition of planet that would avoid such proliferation, while honoring the historical status of Pluto as an exception to the new rule. When the IAU meets again 3 years from now, I suspect that such an alternative will be considered by the astronomers -- with plenty of time to spare before "New Horizons" reaches its final destination.

Killer Asteroid Politics

This past weekend, a group of scientists and former astronauts met in San Francisco to discuss the possibilities for averting disaster if one of the hundreds of known potentially hazardous asteroids were found to be on a collision course with the Earth. They were motivated, in part, by the recent discovery that one such asteroid -- known as "99942 Apophis" -- will skim very close to the Earth in 2029, and has a significant chance of actually hitting the Earth seven years later. The central question is: if precise observations during the 2029 passage reveal that Apophis will hit in 2036, what should we do about it?

You might think that these astronomers are just being alarmist. After all, there have been several recent occasions when the news media report on an asteroid that might hit the Earth -- only to retract the claim a few days later, after additional observations rule out a collision. The primary source of these reports is a list maintained by the Minor Planet Center at the Harvard- Smithsonian Center for Astrophysics. Consider the position of the scientists. They are certainly aware that additional observations will often rule out a future impact -- but if they withhold the early predictions they are accused of a cover-up. So instead they update their predictions continuously, the newspapers report on an uncertain impact, and the astronomers are accused of fear-mongering. It's a no-win situation.

Considering the possible consequences of an asteroid impact, I would rather know about it as far ahead of time as possible. It's similar to the early predictions by meteorologists tracking the path of a hurricane. The uncertainties grow larger as they extrapolate the observations further from the storm's current location -- but the advance warning helps residents of the potentially affected areas to begin preparing for the worst. In the case of Apophis, this might mean placing the entire planet on alert, but at least we would have seven years to devise and execute a plan for avoiding doomsday.

The age of the dinosaurs came to a sudden end when a large asteroid struck near the Yucatan peninsula in the Gulf of Mexico. If humans are smart enough, we can avoid a similar fate.

Budget Uncertainties

More than 4 months into the current fiscal year, the U.S. government still hasn't passed a budget. The administration has already released its budget request for the next fiscal year, which begins in October. This is not the first time we've seen such long delays in the funding of government programs -- including scientific research and development -- and it probably won't be the last. But these annual delays undermine the ability of federal agencies to engage in the long-term planning that could improve the overall efficiency of government.

After the elections in November, the lame-duck Congress passed only 2 of the 11 appropriations bills needed to keep the government running. So, while the Departments of Defense and Homeland Security were fully funded, all other federal programs were asked to continue operating at last year's budget levels through mid-February. The idea was to force the newly elected Congress to spend its first weeks debating the unfinished business of the outgoing Congress. But it didn't work, and in late January the incoming Congress was poised to extend last year's funding levels through the end of this year.

This was a particularly unpleasant prospect for science funding, since several federal agencies (including the National Science Foundation) had been promised significant budget increases this year as part of the American Competitiveness Initiative announced in the State of the Union address in 2006. Without an appropriations bill, this extra funding would simply disappear. Fortunately, last week Congress included a last-minute provision to restore the promised budget increases for several agencies that support scientific research.

A typical grant from the NSF to an individual researcher lasts for 3-5 years, so this effectively sets a minimum planning timescale for the agency. Long annual budget delays create serious inefficiencies in the system -- inflation erodes the value of last year's budget dollar, forcing program cuts to make up any gap, and budget increases that arrive late need to be spent on a shorter timescale. There must be a better way to fund science.