I just got a note from my friend Jim Oberg that the Federal Aviation Administration is warning pilots to be on the lookout for falling debris from USA 193!

8/5536 - SPECIAL NOTICE

.. THIS NOTAM REPLACES FDC 8/5501 DUE TO ADDITION OF CONTACT NUMBER. EFFECTIVE IMMEDIATELY UNTIL 0803092300 UTC. AIRCRAFT ARE ADVISED THAT A POTENTIAL HAZARD MAY OCCUR DUE TO REENTRY OF SATELLITE USA-193 DEBRIS INTO THE EARTHS ATMOSPHERE. FURTHER NOTAMS WILL BE ISSUED IF MORE INFORMATION BECOMES AVAILABLE. IN THE INTEREST OF FLIGHT SAFETY, IT IS CRITICAL THAT ALL PILOTS/FLIGHT CREW MEMBERS REPORT ANY OBSERVED FALLING SPACE DEBRIS TO THE APPROPRIATE ATC FACILITY TO INCLUDE POSITION, ALTITUDE, TIME, AND DIRECTION OF DEBRIS OBSERVED. FAA HEADQUARTERS, AIR TRAFFIC SYSTEMS OPERATIONS SECURITY, 202-493-5107, IS THE FAA COORDINATION FACILITY. WIE UNTIL UFN

I’ve poked around online and had a hard time finding this particular NOTAM; the FAA sends out a lot and this one may be scrolled off the current list. However, it looks legit (I’ve seen other credible sources who have reported it). So if you’re in a plane over the next few days, keep a lookout!

Well, nuts.

A little over a year ago, NASA announced it had found strong evidence of liquid water flowing, at least temporarily, on the surface of Mars. Pictures taken a few years apart showed flow-like gullies in the sides of craters, and there were a few different pieces of evidence that these were due to sudden flooding of liquid water downhill. Here are the original shots:

However, a new study just released says that these images fit better with being dry grains flowing downhill.

The researchers, led by Jon D. Pelletier of The University of Arizona, used HiRISE, the very high-resolution camera on board the Mars Reconnaissance Orbiter, to look at the same regions as observed before. By taking images at different angles, they could establish a digital elevation model, a topographical map of the same crater shown in the earlier announcement. They then modeled the way liquid water would flow under Martian conditions compared to how dry grains would flow. To their surprise, they found that dry grains were a better match. From their press release:

“The dry granular case was the winner,” said Pelletier, … “I was surprised. I started off thinking we were going to prove it’s liquid water.”

Finding liquid water on the surface of Mars would indicate the best places to look for current life on Mars, said co-author Alfred S. McEwen, a UA professor of planetary sciences.

“What we’d hoped to do was rule out the dry flow model — but that didn’t happen,” said McEwen, the HiRISE principal investigator and director of UA’s Planetary Image Research Laboratory.

An avalanche of dry debris is a much better match for their calculations and also what their computer model predicts, said Pelletier and McEwen.

While this isn’t conclusive, it does seem compelling (they can’t rule out very thick mud, incidentally). The press release doesn’t have any statements from the scientists who made the previous announcement about water, and I’ll be very curious indeed to hear what they have to say.

If it holds up, it’s too bad. I’d love to see better evidence of ubiquitous water on (or immediately under) the surface of Mars. But facing reality is what we have to do. Of course, as our tools get better, we’ll get better at figuring this stuff out, too. It helps that so many people involved are so very clever.

A final note: I reread my original blog post about the announcement of possible water. While I think the content of my post was suitably skeptical, I let my feelings get away from me a bit in the headline: "LIQUID WATER ON MARS!" Hmmmm. Looks like sometimes I need to remember my own advice.

Warning: Doctor Who intensive material follows. Spoilers for "Blink", too.

So as a reward to myself for finishing up a pile of work, I watched the Doctor Who episode "Blink." This is the second time I have seen it, and it was even better this time. Honestly, even if you are not a Who fan, this one episode stands out. I’d put it up against any other single episode of any show, including "Out of Gas" in Firefly.

Anyway, I think I have found an inconsistency, and it’s making me insane. What follows are spoilers, so if you’ve seen it, help me out. If you haven’t, then get it! Watch it! Love it!

So the detective shows Sally the cars and the TARDIS parked in the police station. He says they’ve had it a while, it’s their crown jewel of the collection. What must have happened is that after the Doctor and Martha are sent back to 1969 by the angels, the police found the box at the house and moved it.

But then later, maybe that evening, Sally and Larry are at the abandoned house, and she finds the TARDIS in the basement!

I can’t see how that’s anything but a mistake. I even tried to think of some way for the Doctor to have taken the TARDIS to that house after all the events we see (he knows she was in the house when he "talks" to her — best conversation scene ever written, ever, by the way), but it’s a stretch, and I don’t think this is how it was meant to have happened…

Sally sends the TARDIS in the house back to 1969, rescuing the Doctor and Martha (but not the detective! That seems cruel). Then he takes it back to the house and leaves it there for her to find — maybe he shows up just an hour before she and Larry come to the house. Then the Doctor and Martha walk to the police station, grab the TARDIS sitting there, and off they go!

That actually works. However, it means the TARDIS is in two places at the same time, and it may be that the TARDIS in the basement is in some sort of causal loop. Also, and I have to stress this, he leaves the detective in 1969. He has to, I know, but yikes.

So, does this make sense?

Still, what a story! This is up there with The Terminator for sheer time travel wonderfulness, and of course, wibbley-wobbley timey-wimeyness.