UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN

The hunt for signs of life on seven nearby exoplanets will likely begin just a few years from now.

An international research team announced today (Feb. 22) that seven roughly Earth-size alien worlds orbit the small, dim star TRAPPIST-1, which lies just 39 light-years from Earth. (For perspective: Our Milky Way galaxy is 100,000 light-years wide. The closest star to the sun, Proxima Centauri, is about 4.2 light-years away.)

Three of these planets appear to be in TRAPPIST-1's "habitable zone," the range of distances where liquid water (and, by extension, life as we know it) could potentially exist on a world's surface. And all seven may be capable of harboring water, given certain atmospheric conditions, study team members said. [Images: The 7 Earth-Size Worlds of TRAPPIST-1]

This combination of proximity and potential habitability makes TRAPPIST-1 an inviting target in the search for E.T.

"Looking for life elsewhere, this system is probably our best bet as of today," study co-author Brice-Olivier Demory, a professor at the Center for Space and Habitability at the University of Bern in Switzerland, said in a statement.

**Characteristics of the seven TRAPPIST-1 worlds, compared to the rocky planets in our solar system.**
**Credit: NASA/JPL-Caltech**

Follow-up investigation of the TRAPPIST-1 worlds has already begun. For example, last year, observations by NASA's Hubble Space Telescope revealed that the two innermost planets do not possess large, puffy atmospheres, suggesting that the worlds are rocky rather than gaseous. (The discovery team announced in May 2016 that TRAPPIST-1 hosts three roughly Earth-size planets; the new study, which was published in the journal Nature, identifies a total of seven worlds orbiting the star.)

The team continues to study the TRAPPIST-1 system with Hubble. But such work can characterize atmospheres only in a relatively broad sense; the hunt for possible signatures of life such as oxygen and methane will require new instruments, the researchers said.

Luckily, such gear will be online soon. NASA's $8.8 billion James Webb Space Telescope (JWST) is scheduled to launch in late 2018, and three huge ground-based instruments — the European Extremely Large Telescope (E-ELT), the Giant Magellan Telescope (GMT) and the Thirty Meter Telescope (TMT) — should start observing the heavens by the early to mid-2020s.

Indeed, the TRAPPIST-1 system will likely be one of the first targets for JWST once the telescope is operational, Nikole Lewis, an astronomer at the Space Telescope Science Institute in Baltimore and co-leader of the 2016 Hubble study, said during a press briefing today. JWST's observations should allow astronomers to get a good handle on the TRAPPIST-1 planets' atmospheres by the early 2020s, Lewis added.

JWST, E-ELT, GMT and TMT will all be capable of sniffing out "biosignature" gases, their builders have said. (The big ground-based scopes will also be able to image a number of exoplanets directly, but the TRAPPIST-1 worlds aren't good candidates for such photography because they're so close to their parent star, study team members said.)

Detecting either oxygen or methane by itself in a planet's atmosphere wouldn't be compelling evidence of alien life, because both of these gases can be produced by abiotic as well as biotic processes, astronomers have stressed. Finding the two of them together, however, would be a different story.

"They destroy each other," Shawn Domagal-Goldman, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in 2014 during a NASA panel discussion about ancient Earth and habitable exoplanets. "If they're both there together, you know someone is bringing the methane in an atmosphere rich in oxygen, so that's what you're looking for. The most likely explanation is, it's life that's bringing the methane and oxygen to the party."

**Artist's illustration of the surface of a planet in the TRAPPIST-1 system, which hosts seven roughly Earth-size worlds.**
**Credit: NASA/JPL-Caltech**

So astronomers will likely search for methane, oxygen and other gas combos in the skies of the TRAPPIST-1 worlds when JWST and the big ground scopes become operational. But even success on this front would not necessarily provide universally accepted, slam-dunk evidence for life, said Michaël Gillon of the University of Liège in Belgium, leader of the new TRAPPIST-1 study.

"We will never be 100 percent sure until we go there, or get something," Gillon told reporters Tuesday (Feb. 21). (By "get something," he meant a signal from an alien civilization.)

A robotic probe won't be zooming through the TRAPPIST-1 system anytime soon, but this prospect is not out of the question. Last year, a team of scientists and engineers announced the $100 million Breakthrough Starshot project, which aims to develop the technology required to blast tiny, sail-equipped probes through space at up to 20 percent the speed of light using powerful lasers.

If Breakthrough Starshot pans out, such spacecraft could conceivably make it to the TRAPPIST-1 system about 200 years after lifting off.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

IN BRIEF

NASA has discovered more than 2,000 exoplanets that could potentially be home to some sort of life – but we know very little about them. Today, that all changed, as NASA unveiled a solar system with a staggering 7 Earth-like planets that are similar in size and density to our own.

ALIEN WORLDS

It wasn’t too long ago that we thought Earth was the only habitable planet in the universe. But recent advancements in space technology have led to the discovery of one exoplanet after another, leading to the conclusion that life must exist outside of Earth.

To date, astronomers have identified a few alien planets that could potentially support life. For example, five exoplanets that are particularly promising are Wolf 1061C, a rocky exoplanet about the size of the Earth that is 13,8 light years away; Gliese 832C, a larger planet dubbed a “super-Earth;” Gliese 667Cc, which is 22light-yearss away in the Scorpius constellation; TRAPPIST-1d located in the Aquarius constellation; and Gliese 163C in the Dorado constellation.

These five are some of the closest Earth-like planets in the habitable zone of their parent star, but they are by no means the only ones that have been identified. NASA has actually discovered more than 2,000 planets that could be home to alien life – but for the most part, we know very little about them.

Today, everything changed.

NASA just held a press conference announcing the discovery of a solar system that has a host of Earth-sized planets. Three of these are located firmly in the habitable zone, meaning that they very likely have liquid water and could host life.

Here’s everything you need to know about these finds.

REDDIT AMA

According to NASA’s Reddit AMA, this discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system. Here are the other highlights:

How long would it take with current technology to get to this solar system?

NASA: Right now, there is no current technology that can get us to the new planetary system. That’s why we will use space-based telescopes to “remotely” investigate by observing the planets from afar. To see fledgling efforts to send tiny space craft to a different star (with one known planet) see this link.

Do we know the gravity, compared to Earth or Mars, on those 3 planets that could have water in them?

NASA: Determining the surface gravity requires knowledge of both the radius and mass. The uncertainties on the mass measurements are large, but our best guess is that the surface gravity of most of these planets is similar to that on Earth. One exception is planet f. It has the same radius as Earth but 68% the mass. That means the surface gravity will be 68% lower than on Earth.

What is the protocol if you do find any signs of life on any of the exoplanets? How long would it probably take from time of discovery to an actual announcement to the public?

NASA: We do not yet have a protocol. Most likely, we will make a tentative discovery that will take longer to confirm. But that is a great question, and something that has been thought about a lot by many different organizations. There is a great article on this by SETI scientist Dr. Duncan Forgan, which looks at many different scenarios in the age of 24-hour news and social media

Can we expect to have the technology in the next 20-30 years that we could see, for sure, that there would be life in those planets in form of vegetation?

NASA: In order to see vegetation and any other surface features (e.g. oceans, continents), we’ll need future telescopes beyond JWST [the James Webb Space Telescope, set to launch in 2018] that will be able to directly image exoplanets. JWST will observe planets transiting their host stars. Transits are when the planet passes between us and its star, and from these transits, we can observe how gasses in the planet’s atmosphere interact with starlight passing through the atmosphere. Unfortunately, this technique doesn’t allow us to see the surfaces of exoplanets. To do that, we’ll need future technology that may become available in the coming decades that will allow us to block out the star’s light and observe the planets directly. Examples of these technologies are starlight suppression tools called coronagraphs and starshades. The planets we observe directly with these starlight suppression techniques will not be spatially resolved: they will literally be single points of light, but don’t despair because we can still learn a lot from single points of light!

When should we expect the data/results around atmospheric composition to be released or published?

NASA: The first observations of the newly discovered planets are underway, as soon as the results successfully pass through the scientific peer review process we will be able to share what we are learning. Stay tuned this system has lots more exciting things to teach us.

How well can Kepler spacecraft detect planets around TRAPPIST-1 compared to Spitzer spacecraft?

NASA: Kepler can observe for about 80 days consecutively and will, therefore, provide a very important time series and information on the gravitational interactions between the planets which cause timing variations. It is possible that there may be additional planets not seen by Spitzer in 20 days which Kepler could uncover. Kepler and Spitzer have comparable capabilities for the detection of planets around the TRAPPIST-1 system.