Looking for extraterrestrial life in all the wrong places

Alpha Centauri, the closest star system to the Solar System. 

Astrophysicist René Heller of McMaster’s Origins Institute says our planet may not be the most ideal place for life and scientists need to consider non-Earth-like, so-called “superhabitable” planets.

Credit: European Southern Observatory

Scientists have long focused their search for extraterrestrial life on Earth-like planets – but that may be a mistake, according to the McMaster researchers.

Astrophysicist René Heller of McMaster's Origins Institute says our planet may not be the most ideal place for life and scientists need to consider non-Earth-like, so-called "superhabitable" planets.

These planets would probably be two or three times more massive and much less mountainous than Earth. They would probably be older, too.

René Heller

"The Earth just scrapes the inner edge of the solar system's habitable zone – the area in which temperatures allow Earth-like planets to have liquid surface water," says Heller.

"So from this perspective, Earth is only marginally habitable. That led us to ask: could there be more hospitable environments for life on terrestrial planets?"

Heller and co-author John Armstrong of Weber State University describe superhabitable planets in a paper published in the journal Astrobiology early in January.

In it, they outline some of the characteristics such planets might have. They include many, shallower bodies of water (rather than a few large oceans), a more reliable global "thermostat" that impedes ice ages, and a magnetic shield, to protect the planet from cosmic radiation.

John Armstrong

Heller says the theory means astronomers should be aiming their telescopes at planets that have so far not garnered much attention in the search for extraterrestrial life.

"We propose a shift in focus," he says. "We want to prioritize future searches for inhabited planets.

We're saying 'Don't just focus on the most Earth-like planets if you really want to find life.'"

But is the discussion about which planets to look at even worth having? How likely are we ever to find life on another planet?

"Statistically speaking, I would say it's very unlikely that there is nothing out there," says Heller.

"For the first time in history, we have the ability – both technical and intellectual – to find and classify potentially inhabited planets. It's just a matter of how we spend our observation time."

Heller expects the paper to serve as a launching point for a debate about superhabitability. He says it may take some time for the scientific community to come around to the theory.

"When you follow a certain pattern for decades, it can be hard to change your mind."

More information: Read the complete paper here: arxiv.org/ftp/arxiv/papers/1401/1401.2392.pdf

Engaging Maximum Thrust to Explore the Univers

The Apollo 10 moon probe is currently listed as the fastest manned vehicle in history, having reached a maximum speed of 39,895 kilometres per hour. At this speed, it would take 120,000 years to cover the 4 light years to Alpha Centauri, the nearest star system.

So if we want to explore the depths of deep space and journey to Alpha Centauri and beyond, we're going to need some new technologies. Here, we look at 10 of the most intriguing.

The technologies range widely in their plausibility. Some, we could more or less build tomorrow if we wanted to, while others may well be fundamentally impossible.

Ion thruster
Conventional rockets work by shooting gases out of their rear exhausts at high speeds, thus generating thrust. Ion thrusters use the same principle, but instead of blasting out hot gases, they shoot out a beam of electrically charged particles, or ions.

They provide quite a weak thrust, but crucially they use far less fuel than a rocket to get the same amount of thrust. Providing they can be made to keep working steadily for a long time, they could eventually accelerate a craft to high speeds.

They have already been used on several spacecraft, such as Japan's Hayabusa probe and Europe's SMART-1 lunar mission, and the technology has been improving steadily.

A particularly promising variant is the variable specific impulse magnetoplasma rocket (VASIMR). This works on a slightly different principle to other ion thrusters, which accelerate the ions using a strong electric field. Instead, VASIMR uses a radio-frequency generator, rather like the transmitters used to broadcast radio shows, to heat ions to 1 million °C.

It does this by taking advantage of the fact that in a strong magnetic field, like those produced by the superconducting magnets in the engine, ions spin at a fixed frequency. The radio-frequency generator is then tuned to that frequency, injecting extra energy into the ions and massively increasing the thrust.

Initial tests have been promising, and if all goes well, VASIMR could be used to take humans to Mars in 39 days