As researchers plot their space plans to discover where possibilities lie for a home planet like Earth, that might even be supporting our ancestors, where are they looking? MIT astronomers comprising an international team in Belgium are plotting for a search about 40 light years away. That means if we don’t want a spaceship to arrive with astronauts dead of old age or perhaps affected by age-related dementia, we have to send astronauts in the age group of 20s-40s to manage the forty year flight mission. It may take another decade or two for space agencies to have the ability to travel that far so elementary and middle school children of today are the astronauts of tomorrow that may be slated for just such a mission.
Beyond our solar system is the best bet for finding life like our own, or at least a few planets like ours. An MIT team has discovered three planets that orbit a dwarf star about 40 light years away. Their sizes are about the same as Earth or Venus. The telescope the astronomy used to locate them is the TRAPPIST telescope located in Chile. This telescope is designed to specifically focus on a cluster of dwarf stars, 60 in number. Belgian scientists created TRAPPIST to study the infrared wavelengths of dwarf stars and the planets surrounding them.
The scientist’s favorite dwarf star is an ultracool (as in thermally ultracool, not socially hip) star about the size of Jupiter and much cooler than our own sun. Beginning a period of observation in September, 2015, the astronomy team observed regular intervals of fading in the infrared signature of the star. They theorized that planets were passing in front of the star causing this to occur.
The team turned their attention to the time to expect a light fade event and discovered that there were, indeed, planets orbiting the star. The two nearest planets were similar in size to our own Earth and Venus. The closest planet that has everyone’s attention is named 2MASS J23062928-0502285, commonly called TRAPPIST-1. The two planets have orbit cycles, respectively, of 1.5 of our own days and 2.4 days. The amount of radiation they absorb from their star is significantly more than what we deal with. The closest one receives about four times the radiation we get and the next one about two times the amount. So, if there is any life there it would have to have evolved with natural radiation tolerance.
The third planet in distance from the star has an unknown orbit cycle. The scientists’ best guess so far is that it could be anywhere from four to 73 days but would receive significantly less radiation. I guess that’s good news. If we need to relocate I suppose we could deal with a four-day long day or even a two-month long day and not have to worry about skin cancer.
When the team analyzes the size of the planets in relation to the star, and take into account their proximity to their sun, they believe that life could be sustainable. They calculate that there could be areas with a temperature range less than 400 kelvins. That converts to about 260 degrees Fahrenheit or 127 degrees Celsius. Not exactly a tropical paradise but conditions where liquid water and organic life could survive.
The next step is to study the atmospheric conditions of the planets to see what their atmospheres are composed of. What kind of gases? Is there breathable oxygen? And they believe that within their own working career’s lifetime they will be able to determine if these planets are inhabited with life of some kind, say the next ten years or so.
This is a breakthrough in science. Traditionally scientists have studied bright solar stars like our own. By taking a risk and searching for a cool dwarf star, this MIT group has hit paydirt with the find of a lifetime. To accomplish their task they had to design a whole new set of instruments specialized to detect the radiation emitted by cold dwarf stars and only visible through an infrared telescope. The whole field of detecting other worlds changed simply by changing the wavelength humans were viewing the galaxy with. Perspective is everything.
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