Scientists at NASA have re-established contact with the Kepler telescope. The £395 million (more than $550 million) planet-hunting telescope entered emergency mode last week, raising concerns about whether the hunt for earth-like planets could go ahead. Scientists are now hopeful that the next phase of the mission will proceed.
The spacecraft entered emergency mode just days before it was due to begin its new phase.
According to Charlie Sobeck, the mission manager, "The spacecraft is nearly 75m miles from Earth, making the communication slow. Even at the speed of light it takes 13 minutes for a signal to travel to the spacecraft and back."
Nasa has re-established "solid contact" with the craft after several days of only sporadic contact. The cause of the emergency is still unclear, and ground controllers are investigating what triggered the problem.
The discoveries of Kepler have been the source of much excitement and media intrigue. Late last year there were reports that Kepler may have discovered an alien megastructure, according to Discovery News.
During that phase of the mission, Kepler was using the Transit Method to try to identify earth-like planets. This technique involves monitoring the brightness of stars and watching for dips in brightness that occur when a planet crosses the star's face. Any transiting planet will momentarily block some of the star's light.
Kepler has used the Transit Method to identify more than 2,700 potential planets since its March 2009 launch.
"Astronomers also look for variations in the timing of a particular planet's transit, because these can reveal the presence of additional worlds orbiting the same star."It's not just planets that can be spotted by Kepler. A star's dimming could be caused by an alien megastructure occasionally blocking the light.
"Imagine an advanced civilization that's well up on the Kardashev scale and has the ability to harness energy directly from its star. This hypothetical alien civilization may want to construct vast mega-structures, like supersized solar arrays in orbit around their host star, that could be so big that they blot out a sizable fraction of starlight as they pass in front."The Kardashev scale is a system of ranking the technological advancement of civilizations, posited by astronomer Nicolai Kardashev. It suggests that more advanced civilizations will be able to -- and, perhaps, need to -- harness more energy in order that they can direct it towards communication. For example, an advanced Type 2 civilization -- more advanced than earth -- may need to build a mega-structure around its sun to harness all the energy that is available from that source.
"A Type I civilization is able to utilize and store energy available from its neighboring star which reaches their planet, Type II is able to harness the energy of the entire star (the most popular hypothetic concept being the Dyson sphere—a device which would encompass the entire star and transfer its energy to the planet), and Type III civilization are in control of energy on the scale of their entire host galaxy."The energy-harnessing mega-structures would probably be spherical in shape, surrounding the sun or star like a cage encircling a firefly. The spherical model is called a Dyson Sphere after physicist Freemon Dyson, who popularized the concept in one of his essays.
Dyson reflected that aliens would almost certainly build such a structure around their central star -- it would be "the logical consequence of the escalating energy needs of a technological civilization and would be a necessity for its long-term survival."
"Scientists have long theorized that advanced alien civilizations might begin to harness all the power of their home star, requiring massive powerplants known as Dyson Spheres or Dyson Swarms, named for Freeman Dyson. Dyson first proposed these structures, and none have been found to date, of course. Otherwise we'd know for sure we weren't alone."The excitement last year was caused when the Kepler telescope detected a dimming star that seemed to be transited by an object that was not round.
"Say if Kepler detects something that isn't round... In other words, what if it's alien?"By November, the Telegraph reported that scientists had ruled out the possibility that that particular star was providing for an alien civilization's energy needs. SETI trained its Allen Telescope Array on the star for more than two weeks and did not detect any promising signals.
For Kepler's new mission, scientists will not use the Transit Method but will use a technique called gravitational microlensing, a slightly more complex technique. In microlensing, light from distant stars is used to analyze the characteristics of transiting objects that are closer to earth (ie. not an orbiter of the distant star), and which could themselves be stars rather than planets. In microlensing, the nearby object's gravitational field bends and magnifies the light from the distant star, acting like a lens.
"This produces a light curve — a brightening and fading of the faraway star's light over time — whose characteristics tell astronomers a lot about the foreground object, which is often a star. If this star has any planets, these can generate secondary light curves, alerting researchers to their presence."Space reports that Kepler will still be able to hunt for alien life throughout its next phase, as it switches from the Transit Method to the microlensing technique.
Some people have proposed that the human race itself should consider building a structure around the sun to harness its power.
"Humankind is energy hungry...When demand outstrips what we can reap from Earth and its vicinity, what will our power-craving descendants do? A bold solution: the Dyson Sphere."Futurist George Dvorsky proposes building a Dyson Sphere around the Sun by basically destroying Mercury and using it for parts. Others claim this is impractical because destroying Mercury would require so much energy the project would, in fact, be an energy sink.
[AP Photo/NASA, File]