Tantalizingly close exoplanet still out of reach
Proxima b shows the need for more powerful observatories, spacecraft
Typing “Proxima b” into a search engine quickly yields an image of the newly discovered planet in all its purported glory. A sun hanging low above the horizon casts long shadows on a rough, reddish and rocky terrain. Two bright stars hover above its shoulder, growing ever brighter, with just a hint of a cloud in the distance.
Of course the image is little more than a fanciful artistic rendering, the sort of thing we might have seen on an episode of Star Trek, which made its debut on network television 50 years ago today.
Proxima b is real, yet exists mostly in the imagination. As with others on the growing list of “Earth-like” exoplanets found to be orbiting nearby stars, details are in short supply. The real reason for the intense interest and big headlines around the world was one simple fact — it is tantalizingly close.
In the words of one astronomer, it’s like a neighbor is holding up a sign saying “Hey, look at me.” How scientists might do so, though, is a vexing matter, given that we can’t yet see it. Galactically speaking, Proxima b may be just around the corner. But the galaxy is a big place, and the corner is about 25 trillion miles away. New spacecraft needed
Finding more Earth “twins” in the so-called Goldilocks zone — not too close to their star and not too far away — is all the rage. So much so that when another one pops up, talk quickly turns to the possibility of life and of an urgent need to know more, perhaps even to go there on a scouting expedition.
If nothing else, the rise of the exoplanet both as an astronomical discipline and fodder for popular culture underscores two vital needs — one for more powerful observatories to help fill in the immense gaps of basic knowledge, and the other for revolutionary types of spacecraft propulsion, which would provide a way of actually getting somewhere that we cannot with today’s space probes putt-putting along on tiny, underpowered engines.
Proxima b may be exciting because it is “only” 4.2 light years from Earth. But 4, 40 or 400 is all the same when it comes to actually seeing it up close, even with a small robot, until spaceships can travel orders of magnitude faster than now is doable. Only in NASA’s dark corners and in a few small labs far from the beaten path is this kind of work taking place, and their days as headline makers are far down the road. We may long for Capt. Kirk’s warp drive, yet only a handful of researchers are engaged in the search for it. We look because we can. “There are topics that fascinate us — dinosaurs and black holes and now exoplanets,” said Yale University astronomer Debra Fischer, whose team is one of many devoted to finding planets similar to Earth. “We are newcomers on this tiny little speck of a planet on the edge of a galaxy. We look out and realize how we are part of something so vast, so it’s natural to speculate on what may be out there.”
The good news is that the small arsenal of telescopes and observatories, based on Earth and in space, is growing in number and sophistication. NASA’s Kepler mission, launched in 2009 and placed in a solar orbit that trails Earth, is tasked with exploring a small section of the sky for Earth-like planets. So far it has found 21 that are less than twice Earth-size and are situated at a distance from their stars that is considered a habitable zone.
Proxima b was discovered using the European Southern Observatory’s 3.6-meter telescope. Michael Endl, an astronomer with the University of Texas, was part of the group that provided the initial data suggesting a planet near the Proxima Centauri red dwarf star, our sun’s closest neighbor. Interesting stuff, but not conclusive, so Endl eventually moved on to other potential targets. Then a different group of scientists looked again at Proxima Centauri, albeit using a different instrument and telescope. They also saw data suggestive of an orbiting planet and suggested he look again. ‘A huge deal’
“A game-changer,” was the description of Oliver Guyon, an astronomer at the Jet Propulsion Lab in California, which does a lot of exoplanet hunting and also builds and manages many of NASA’s robotic science missions.
“That’s a huge deal,” Guyon said in a JPL news release. “It also boosts the already existing, mounting body of evidence that such planets are near, and that several of them are probably sitting quite close to us.”
Endl is hopeful that the coming years will see the completion of a robust sci- entific profile of Proxima b as well as similar planets, yet unfound. Within a couple of decades, he said, we should have a good idea about their density, magnetic fields, and atmospheric status, the last of which could offer evidence of “biosignatures,” those features which are conducive to life.
Large and more complex Earth-based telescopes are under construction, as are new space observatories, including the upcoming James Webb Space Telescope, successor to the legendary Hubble, and the exoplanet-hunting Transiting Exoplanet Survey Satellite (TESS). Others will follow, possibly including the LUVOIR observatory — Large UV/Optical/Infrared surveyor — that Fischer is helping to design. If approved, it would be placed in a gravitationally stable position out past the moon.
“Exactly what weare trying to find out — the answer to that ancient question of are we alone — is possible if we built up a big enough target sample of nearby planets and studied them in detail,” Endl said. “The star is so nearby that we will have the opportunity to study the planet in detail. We can throw everything at it that we have.”
Even at this close range, however, observation from or near Earth has inherent limitations. A thorough examination will require a machine to get near it. Proxima b’s location means we don’t have to fully lapse into science fiction to imagine an eventual rendezvous, but it is still a haul. A spacecraft moving 1 million miles per hour would take more than 2,500 years to get there. The fastest of NASA’s various space probes was Juno, now in Jupiter’s orbit, which reached a speed of 150,000 mph. It takes a lot of money
Propulsion is the ultimate limiting factor when it comes to exploration. Those involved with advanced propulsion research imagine a day when current technology looks to us like Orville and Wilbur Wright’s early airplanes appear today. But such work is haltingly funded and far from a priority.
That fact has long bothered former astronaut Franklin Chang-Diaz, who spent 25 years with NASA and flew seven missions on the space shuttle. Like so many Americans emboldened by the Apollo program, Chang-Diaz figured that 2016 would see us established on Mars and having spacecraft that could at least move us through our solar system quickly.
“We talked about going to Mars and these other place in the solar system, but there was no mainstream program to power the ships to get there,” said ChangDiaz, who was researching propulsion when he joined the astronaut corps in 1980. “The whole space program was frozen in time.”
So, after leaving NASA in 2005, Chang-Diaz helped found the Ad Astra Rocket Company in Houston to develop an in-space engine than could move a large mass faster. He likens the VASIMR plasma engine to a diesel, a functional power source that serves the purpose of travel through the solar system.
“It will not get us to the stars, but it will be enough to move around the solar system with agility,” Chang-Diaz said of his engine, which will soon undergo a demonstration test in a vacuum chamber to be built in AdAstra’s Houston facility. “We need to start thinking differently and doing the right homework to write the next chapter.”
That’s where scientists like former Fermilab researcher Gerald Jackson fit in. He and a colleague created Hbar Technologies in hopes of creating an antimatter drive. The physics behind it work, Jackson insisted, but the engineering details will be a challenge. Step one is a $200,000 Kickstarter campaign to fund a scientific demonstration to prove the concept.
“If it worked, it might get us up to 10 to 20 percent of the speed of light,” he said. “That could get us to Alpha Centauri in 40 to 45 years.”
Not exactly the Starship Enterprise, though not a bad next chapter. As with everything space related, it gets back to money to prove the idea’s merit. The best case scenario is that one of the next-generation observatories finds a biological signature among the best and nearest Earth-like planets, in which case guys like Jackson could just find themselves everybody’s new best friend.