NASA just scored a double whammy: water is now confirmed for the first time ever on Mars and a liquid hydrocarbon lake, which is the only other place in the solar system that has liquid on its surface.

First Mars: For the past few days, the Phoenix Mars Lander has been having problems getting icy soil unstuck from its bucket scooper. And just four hours ago, NASA announced, on twitter, that the ice is chemically confirmed to be water. The robotic arm delivered the soil sample to an oven which then heated the soil and the water vapor observed. We've had evidence for water on Mars for a while now but this is the first confirmation by chemical "tasting".

The sample came from a frozen layer 2 inches deep under the Martian surface soil. The sticky soil was difficult to move into the oven and so the sample was exposed to the Martian air to get some of the water to evaporate and make it easier to handle. The oven is known as Thermal and Evolved-Gas Analyzer, or TEGA.

For more Pheonix updates, follow @MarsPhoenix on twitter and keep an eye on the Lander's home page on NASA's website.

The other news is of Cassini finding a liquid lake on Saturn's moon Titan. Before Cassini, scientists thought Titan would have global oceans of methane, ethane and other hydrocarbons. Now after more than 40 close flybys of Titan by Cassini, we have not seen any such oceans. Instead, hundreds of dark, lake-like features were seen but we weren't sure if they were made of dark material or really lakes.

The results came from a mapping instrument of lake Ontario Lacus, in Titan's south polar region, during a close Cassini flyby in December 2007. The lake is roughly 20,000 square kilometers (7,800 square miles) in area, slightly larger than North America's Lake Ontario, and now is known to be made of liquid ethane. The ethane is in a liquid solution with methane, other hydrocarbons and nitrogen. At Titan's surface temperatures, approximately 300 degrees Fahrenheit below zero, these substances can exist as both liquid and gas. Titan shows overwhelming evidence of evaporation, rain, and fluid-carved channels draining into what, in this case, is a liquid hydrocarbon lake.

Full details about the Cassini's mission to Saturn at the NASA Cassini-Huygens's home page.

Is that cool or what?

Image credits: TOP: This partial view of a full-circle panorama shows NASA's Mars Phoenix Lander and the polygonal patterning of the ground at the landing area. The image is in approximately true color. Image credit: NASA/JPL-Caltech/University Arizona/Texas A&M University. BOTTOM: NASA/JPL/Space Science Institute.

A very interesting paper has just been published about aging in worms. The paper basically uncovers evidence that goes against the current thinking about how and why animals age and might in the future shed light on how and why humans age. Worms? Yes, because they are a good genetic model that is easy to grow and experiment on.

Some background: there are two theories that explain how cells and animals age:

• Cells get damaged and the damage accumulates over time, which leads to cells malfunctioning and dying.

• The control mechanisms inside the cell break over time leading to the cell's processes to stop functioning properly, something descriptively called antagonistic pleiotropy.

Cell damage can come from sources such as cellular stress, free radicals, and disease, and there is evidence to support this theory. The life span of worms can be extended by feeding them harmless bacteria and growing them in conditions that reduce cell damage. Some experimental strains of worms have longer lifespans because they have mutations that allow them to survive stress better. So there is evidence for this kind of thinking but it's not the whole story.

Today's paper uncovers 3 genes that are master control switches for many cellular processes - they control over 1200 genes in total! These genes, known as elt-3, elt-5, and elt-6, interact: elt-5 and elt-6 inhibit elt-3 late in life and lower levels of elt-3 mean that some processes are switched off. When the researchers knocked out elt-5 and elt-6 (i.e. removed their inhibitory effects), high levels of elt-3 were seen in older worms just like in younger worms, and not just that, the worms lived longer - about 25 days compared to 20 days.

So what does this mean? The evidence in this paper looks good and of course it needs to be repeated and validated. Furthermore, it may or may not apply to humans because humans live for decades as opposed to the days a worm lives which could mean that different aging mechanisms may be important in humans. Still, this research opens the door for further experimentation and gives us a handle on how to approach this age-old problem.

Finally a sensible (and civil!) interview with Prof Dawkins in a mainstream news channel, AlJazeera English. The interviewer, Riz Khan, explores the whole evolution/creationism/intelligent design debate (as if we needed one...) in very broad strokes with Prof Dawkins and takes 2 questions via email and one by phone.

My favourite answer is the one that starts around 5:30 min into the interview.

Two years ago, I blogged about how Einstein's E=mc² was supported by experimental evidence. Well now an international group of astronomers have observed evidence that supports another prediction from Einstein's General Relativity from 1915.

The video below explains the experiment, so I'll give some background and a quick explanation. When massive stars die and explode as supernovae, they leave behind an ultradense object called pulsars. One such stellar ruin, affectionately known PSR J0737-3039A/B and lying about 1700 light years away from us, is the only known double pulsar, meaning there are two objects that orbit each other. Actually, they are so close to each other the whole system can fit inside our sun. As pulsars rotate, they emit very powerful radio waves which we can detect on Earth, and that's what allowed the astrophysicists to test Einstein's theory.

What Einstein's theory predicted is that in a system like a double pulsar, the two objects will affect each others motion. The change in motion is a slow one and called a "precession". You can see something similar at home: spin a top but make it spin slightly off-vertical. You'll see the axis of the top rotate slowly, like the image to the right. The question is: can we observe such precession in PSR J0737-3039A/B? Yes we do.

A paper just published in Science magazine describes how such a precession was observed. But don't bother with the paper, just watch the video below.

One of the key experiments in physics is called the double slit experiment. The experiment very elegantly demonstrates why quantum physics is so counter intuitive. The double slit experiment shows that light is both particles and waves. It also tells us that electrons, subatomic particles themselves, can behave like waves. This so-called wave-particle duality is one of the key concepts in quantum physics.

Today's video is a cool cartoon that explains this concept and describes the experiment in simple terms. It really is one of the best explanations I've seen for the subject.

Finally, if you want a reference to dive into further, check out this Physics World article.

In animal brains, there is a gene called the brain-derived neurotrophic factor (BDNF) that is important for neurons in the hippocampus to grow and connect to each other, processes that are the basis of memory and learning. The gene produces a growth factor that makes neurons grow which plays a key role in the initial development of the brain: Mice born without BDNF have developmental deficits and die soon after birth. BDNF is also secreted by neurons in adult brains when synaptic junctions between neurons require strengthening (something called "synaptic plasticity") which again are processes that underly memory and learning. Just in case this is not enough, BDNF production has been linked to exercise and to treating depression.

(Quick recap of The Central Dogma of genetics as it's about to feature in our story: DNA stores the genetic material which is then transcribed into RNA that is then translated into proteins. This DNA->RNA->Protein is at the heart of genetics and molecular biology as it summarizes how genetic material is transmitted between generations (via DNA) and how the DNA controls the cell's processes via the RNA and proteins.)

There's been a weird twist in the BDNF story: when the BDNF gene is transcribed into RNA it makes two different types of RNA, a long one and a short one, differing in the tail length of the RNA that's produced. This is not uncommon in genetics as lots of genes produce more than one type of RNA that end up producing variants of the same protein product. The weird thing about BDNF is that both RNA types end up producing the exact same protein. The question is why does it do that? Why does BDNF need two types of RNA to produce the same exact product when only one would suffice?

The answer seems to be transportation. A paper recently published in the journal Cell shows that the long version of the BDNF RNA is transported down the long axons of nerve cells. Nerve cells can be quite long and the long BDNF RNA has anchors that transport proteins dock to and move the RNA towards the tips of the nerve cells. There, the same exact BDNF protein is made but it is at the tip of the nerve instead near the main body of the nerve cell. Neat!