Recent results from Cluster shed some light on the mechanism that brings particles from the solar wind into the Earth’s magnetosphere, creating the Aurora and radiation belts. The basic mechanism is vortices generated in the sheared flow region between the magnetosphere and the solar wind. The mechanism behind the vortices is called the Kelvin-Helmholtz instability, and it’s fairly generic to low velocity sheared flows, as the discussed in the article.

The same mechanism will affect any craft powered by mini-magnetospheric plasma propulsion (M2P2), but the particle transport will be the other way – from inside the magnetic bubble to outside (since the inner particle density will be higher than the solar wind particle density, at least in the tail region). This will cause loss of ions from the bubble, and may turn out to be the limiting factor for M2P2.

There is a nice picture of Kelvin-Helmholtz waves in the Earth’s atmosphere here.

Hubble is starting to fail.

You know all those things you haven’t done in a blue moon? Well, get ready to do them again tonight.

The Great Wall of China, a river, whatever…it’s all good.

ESA doesn’t seem to know the difference.

Jay Manifold has a post about a mindless desecration in Pennsylvania, based on an email I forwarded him from Jim Oberg.

The April issue of Physics Today has a bunch of articles on planetary science, though only two are available without subscription. The Mars water article looks particularly good, and it’s one of the free ones.

Incidentally, in the letters section there’s a response to a naive letter about the roots of terrorism in a previous issue which hits the nail on the head.

The Martian oceans may yet prove to be a mirage. Scientists analyzing the Martian data may have had a case of mistaken hematite identity:

Although the NASA rover Opportunity has found other evidence that the plain was likely to have been a shallow sea, it has yet to find a single flake of the grey hematite.

“It’s not panned out so far in the images we’re seeing,” said U.S. geochemist Professor Donald Burt of Arizona State University.

Opportunity may be finding the same old red hematite that gives the planet its nickname, eats away at our cars here on Earth and doesn’t require nearly as much water to form.

I’m still more interested in the methane, myself.

They seem to have discovered methane on Mars.

I find this much more exciting than water for two reasons. First, while there are abiological means of methane production (e.g., vulcanism), if there’s been any recent (i.e., in the past few hundred years) such activity, this would be the first and only evidence of it, so some form of life is definitely a strong possibility. Water means that life might have once been there. Methane means much more strongly that it might be there now, since it doesn’t persist that long.

It’s also potentially a source of fuel, though it may be too trace to easily collect.

[Hat tip to “cspackler” at Free Republic, from an amusing thread on this topic.]

[Update a couple minutes later]

The best place to go for in-depth and smart blogging on subjects Martian is probably Oliver Morton’s Mainly Martian site. He’s all over this one, and has taken the effort to come up with flatulent cow equivalents. He thinks it’s just a couple thousand for the whole planet.

Keith Cowing has a nice essay on the current state of our knowledge of Martian history.

Jay Manifold’s comment on this post:

A few years back, when I lived in Dallas, the director of the planetarium at Fair Park told a Texas Astronomical Society meeting that when the planetarium announced that telescopes would be available for public viewing of the Tue 10 Jun 94 annular solar eclipse, they got calls from people asking why they hadn’t scheduled it on a weekend, when more people could drive down to see it.

These calls were from teachers.

…got me to thinking.

His power grows.

How did Glenn manage to schedule the opposition of Mars with his birthday? He moved an entire planet just so he could take the day off from blogging?

Be very afraid.