I thought I'd comment on President Bush's plans for space exploration.  Punch line: I'm strongly in favor.  And I'm impressed that he has time and energy to spend on strategy as well as tactics.

The bottom line is Bush has created an inflection point for NASA; the old expensive programs are being phased out (Shuttle, ISS, etc.) and new ones must be created.  With only $1B more in their budget, NASA will have to be much more frugal to achieve lofty goals like a moon base and manned mission to Mars.  Hopefully they'll be forced to rely on private enterprise much more than in the recent past, and they'll have to create value for private entities in return.  This kind of public/private joint effort is key to successful exploration of space, just as in earlier centuries it led to the exploration of new continents.  Who knows, maybe NASA will auction off extraterrestrial property rights.  I can see it now - eBay's Moon Properties category.  :)

The scientific value-per-dollar of unmanned missions is far greater than that of manned missions.  Sending people in space is hard - people are heavy, their life support systems are complicated and heavy, the margin for error must be much less, and most importantly, the mission must return (although see Paul Davies comments, below).  Indeed there are only two reasons for using people in space missions, first, for the publicity value, and second, because they'll help pay.  The first reason is important; the U.S. public must remain involved and excited in space exploration or they won't tolerate the tax-funded expense.  (However, ask yourself which attracted more support for NASA, the Columbia shuttle mission, or the Spirit Mars rover.)  The second reason is also important; a significant number of wealthy people will pay serious money to travel into space.  Overall attracting funding is the most daunting challenge of all space exploration.

The technical details of the President's proposals are unimportant.  It is the vision which is important; broad new goals which will take years to achieve, and which will stimulate tremendous technological development and scientific knowledge in the process.  Doubtless critics may focus on the expense, and claim "x number of homeless people could be housed and fed for the same money."  Yes, but...  If I'm the taxpayer, this is what I want my money to be used for, not welfare.

Already the President's policy is having effect; NASA is halting all space shuttle missions to service the Hubble Space Telescope.  This doesn't have as much to do with Hubble as it does with shuttle missions, which are expensive and no longer strategic.  "The shuttle is also gradually being wound down, and all remaining flights until it goes out of service in 2010 will be used to complete the International Space Station."  The Hubble has had a great run since its launch in 1990.

The International Space Station is a financial sinkhole, with very little scientific knowledge left to gain; but we have made commitments to other countries which must be fulfilled.

Meanwhile on Mars, Spirit Studies Mars at 'Arm's Length'.  "Scientists detailed another milestone in the traveling road show that is the Spirit rover -- using the fully deployed arm (instrument deployment device, or IDD) to scrutinize the Martian soil in minute detail.  One of four instruments mounted on the arm -- a Microscopic Imager -- has taken the highest resolution picture of the Martian surface to date.  Throughout Spirit’s exploration of Mars, this device serves as a geologist's hand lens, outputting close up views of select rocks and soils."  I love it.

By the way, space.com has excellent Spirit coverage.

Here are some others' interesting thoughts:

Charles Krauthammer: "The president's proposal is a reasonable, measured reconfiguration of the manned space program."

Ken Silber: "In its financial aspects, the Bush plan also is pragmatic -- indeed, too much so. The president's proposal would increase NASA's budget very modestly in the near term, pushing more expensive tasks into the future."

Paul Davies: "Why is going to Mars so expensive?  Mainly it's the distance from Earth.  There is, however, an obvious way to slash the costs and bring Mars within reach of early manned exploration.  The answer lies with a one-way mission."

And check out NASA Watch.  Current missions [ via Michael on Slashdot ]:

The Mars Space Exploration Rovers.  Uh, you know about them, right?

The Kepler Spacecraft which will search for terrestrial planets around nearby stars.

The New Horizons Mission to explore Pluto and the Kuiper belt.

Deep Impact which will fire a small impactor into a comet to study the insides.

Messenger which will fully photograph Mercury for the first time.

The ESA's Herschel Infrared Space Telescope.

The ESA's Rosetta Spacecraft which will land on a comet for the first time.

What a great time for space exploration!