NASA scientists will announce a major discovery this Thursday that could boost the chance of life on other worlds. Experts believe they will say they have found a new form of life on Earth that is completely alien to anything known before. 

NASA, who have called a full scale press conference for tomorrow, have tried to keep their findings under wraps, though an accompanying scientific paper has been released to some journalists under embargo.

Skymania has not seen the paper and so has been free to do some detective work to discover what will be announced. Despite wild speculation on the internet, there is unlikely to be an announcement that extra-terrestrials have been discovered, for the reasons very well put forward by Stuart Atkinson’s Cumbrian Sky.

But our own investigations suggest that it follows a breakthrough in the discovery of microbes in a lake that get their energy from the usually poisonous arsenic. Experts say this shows they had a completely different origin to any other creature known on our planet. It means that life began not just once but at least twice on Earth. Update: The conference has since revealed that, though the microbes appear to have adapted to use arsenic, they do not appear to be an independent life-form, i.e. a shadow biosphere. Read Ed Yong’s excellent take for more.

A key scientist on NASA’s panel will be Dr Felisa Wolfe-Simon who has spent two years investigating Mono Lake, close to California’s Yosemite National Park. The lake has no outlet and has, over many millenia, built up one of the highest natural concentrations of arsenic on Earth.

Geobiologist Dr Wolfe-Simon has been looking to see whether microbes with a totally different make-up to that of conventional carbon-based life could have developed. There was an interesting article about her search for alien life on Earth in NASA’s online Astrobiology Magazine.

The importance that NASA attaches to her discovery and its implications for finding extra-terrestrial life is demonstrated by the fact that they will have on tomorrow’s panel experts on two other sites in the solar system where life might have developed.

They are Pamela Conrad who is looking for life on Mars and Steven Benner who is studying Saturn’s largest moon Titan which has a dense atmosphere like Earth but lakes of liquid methane rather than water. Also on the panel will be ecologist James Elser who is involved with a NASA-funded search for ET.

All life previously discovered is of one basic type because it relies on phosphorus as an essential building block. The newly found microbes seem to use arsenic instead.

Astrobiologist Dr Lewis Dartnell, of the Centre for Planetary Sciences in London, told Skymania today: “Mono Lake has a very high concentration of arsenic dissolved in it which is usually poisonous and consequently there’s not much life.

“I’m 90 per cent certain that Felisa has found something in Mono Lake and they have been able to demonstrate in some way that it uses arsenic in its metabolism rather than be poisoned by it.”

He added: “Phosphorus is key and absolutely essential for life. It forms the backbone of DNA. Every form of life of Earth we have known so far depends on phosphorus as well as another molecule called ATP, an energy storage molecule, or biological battery.

“It is exciting to find life in an arsenic-rich environment. If these organisms are using arsenic in their metabolism, it demonstrates that there are other life forms to that as we know it.”

Dr Dartnell went on: “There is no reason to expect that life arose just once on Earth. It could have arisen any number of times. The only reason that all life we have found so far has all descended from the same progenitor – the same mother of life – is because we’ve been looking for life in the same way.

“But if you start looking in extreme environments like Mono Lake, where our kind of life doesn’t survive very well, that’s where you find fundamentally different life forms with a separate origin. They’re aliens, but aliens that share the same home as us.” (Update: Just for the record, Lewis was not suggesting that a shadow biosphere would be announced by the NASA conference, simply that it was something biologists look for.)

Dr Wolfe-Simon has previously said of her research: “It may prove that there are other possibilities that are beyond our imagination. It opens the door for us to think about biology in ways we have never thought.

“We are going to look for life on other planets and we only know to look for that which we know. This may help us to develop tools to look for something we have never seen.”

Last year NASA revealed the detection of plumes of methane on Mars that offered compelling evidence that there might be life on the red planet.

British space scientist Professor Colin Pillinger, who has devoted his life to finding life on Mars, told Skymania: “If they have found anything which they can attribute to arsenic-based life then it is very interesting and obviously has connotations for other places in the universe where life forms other than the ones on Earth may very well have developed.”

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available. Check out our monthly sky guide too!