"It must be ice," said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson. "These little clumps completely disappearing over the course of a few days, that is perfect evidence that it's ice. There had been some question whether the bright material was salt. Salt can't do that."

The chunks were left at the bottom of a trench informally called "Dodo-Goldilocks" when Phoenix's Robotic Arm enlarged that trench on June 15, during the 20th Martian day, or sol, since landing. Several were gone when Phoenix looked at the trench early today, on Sol 24.

It could be something else, but ice sounds like a pretty good guess.

NASA's Phoenix spacecraft landed in the northern polar region of Mars today to begin three months of examining a site chosen for its likelihood of having frozen water within reach of the lander's robotic arm.

Radio signals received at 4:53:44 p.m. Pacific Time (7:53:44 p.m. Eastern Time) confirmed the Phoenix Mars Lander had survived its difficult final descent and touchdown 15 minutes earlier. The signals took that long to travel from Mars to Earth at the speed of light.

Hooray!

Senior Review and rankings for the ten missions under evaluation for NASA Astrophysics in 2008 have been published.

1. Swift
2. Chandra
3. GALEX
4. Suzaku
5. (Warm) Spitzer
6. WMAP
7. XMM
8. INTEGRAL
9. RXTE
10. Gravity Probe-B

Bottom line here is that NASA funds are too tight, so some operating missions are being reviewed for descoping or shut down.

The new test of general relativity concerns a distant galactic core or quasar called OJ287, which is known to emit a pair of bright optical bursts every 12 years or so. In 1988, Valtonen and others suggested that this emission is powered by a primary black hole 18 billion times more massive than the Sun, around which orbits a second black hole some 200 times lighter. In such a binary system, the lighter object passes through matter in the accretion disk of the primary black hole twice per orbit, releasing a burst of energy each time it does so.

By modelling such a system, researchers could then put general relativity to the test by predicting when the next burst should occur. At the time, the next major bursts (which were due in the mid 1990s) could only be predicted with an accuracy of a few weeks, which was too vague to test general relativistic effects. But early last year, based on refined models and years spent monitoring OJ287, Valtonen and others were able to predict the date on which the next bright pulse should appear: 13 September 2007, give or take a day or two.

To have any hope of detecting the pulse, more than 25 astronomers from 10 countries had to work together. This is because in September OJ287 rises in the east just before sunrise, and is therefore only visible at any one location on Earth for about 30 minutes before the sky becomes too bright. By starting observations in Japan, followed by China, Europe and ending in the Canary Islands, observers were able to follow the sunrise westward around the globe and maximise observing time. In total, about 100 measurements were made between 4 September and 20 October, some of which by amateur astronomers.

The first results from ESA’s Venus Express give weight to the popular theory that our planetary twin once had a similar climate to Earth’s, only for it to evolve into the hell-like place it is today. Among the results is proof that Venus has been steadily losing water as the result of a runaway greenhouse effect, and the first concrete piece of evidence that the planet is home to bursts of high-altitude lightning.

Formed at roughly the same time, orbiting closer than any two Solar System planets and possessing the same radius to within 5%, it is hardly surprising that Earth and Venus are often referred to as twins. But Venus’s barren surface coupled with temperatures reaching 450°C — higher even than Mercury — makes its present climate a far cry from cool, wet Earth.

Will humans ever really go to Mars? Let's face it, the obstacles are quite daunting. Not only are there numerous, difficult, technical issues to overcome, but the political will and perseverance of any one nation to undertake such an arduous task just can't be counted on. However, one former NASA engineer believes a human mission to Mars is quite doable, and such an event would unify the world as never before. But Jim McLane's proposal includes a couple of major caveats: the trip to Mars should be one-way, and have a crew of only one person.

Even more bad news under the save astronomy banner: The Times is running a story today suggesting that the famous telescope at Jodrell Bank faces closure.

I'd gathered from the list of possible cuts on the Save Astronomy website that Merlin was under threat but I hadn't even considered the idea that this might mean that the Lovell Telescope itself would be under threat.

This whole STFC nonsense was depressing to start with, it's almost impossible for me to find the right word to describe my mood now.
Is this it? Has this country given up on physics and astronomy? Has this government now decided that it's really not worth the time or money? I disagree. I'd try and say why I disagree but there's little point when Nigel Hawkes at The Times has done a far better job...

The Pentagon says it has to shoot down a malfunctioning spy satellite because of the threat of a toxic gas cloud. Space security experts are calling the rationale highly unlikely. 'Having the US government spend millions of dollars to destroy a billion-dollar failure to save zero lives is comedic gold,' one tells DANGER ROOM.

Yesterday, Deputy National Security Advisor James Jeffrey said the satellite's tank full of hydrazine rocket propellant was the main reason the military was planning to blast the orbiter. There's a small but real risk that the hydrazine tank could rupture, releasing a 'toxic gas' over a 'populated area,' causing a 'risk to human life.'

They go into some interesting theories, but I think that the largest concern is that they simply don't want this satellite to crashland someplace where an unallied government or other faction (for lack of a better term) will be able to recover and potentially see what the US is up to and capable (or even not capable) of from a technology point of view.

HobbySpace hosts an exhaustive collection of information and links about space-related hobbies, including amateur astronomy, satellite design, and rocketry for both beginners and experts.