Kepler, the planet-hunting space telescope, is dead

3,000 potential exoplanets later, a failed reaction wheel means the end of the Kepler mission.

The Kepler telescope, a one tonne satellite launched in 2009 to scan for planets outside of our solar system, is dead.

Over the four years of its mission, the spacecraft has found over 3,000 stars which might have planets orbiting them, and the earth-based analysis has confirmed 134 planets orbiting 76 of them.

In April, the mission even announced the discovery of two potentially habitable planets. The two were roughly earth sized, and roughly earth temperature as well. Each of them might just lie in the "habitable zone", where liquid water can potentially exist.

Sadly, shortly after that discovery, Kepler ran into problems. The telescope manoeuvres through space with four reaction wheels, which keep it pointing in the right direction using a gyroscope effect. In July 2012, one of the wheels failed, but the mission was designed to only require three to accurately aim. In May this year, however, a second wheel failed. Yesterday, Nasa announced that they had given up trying to fix the wheels. Kepler can no longer be targeted accurately.

But, good news! Rumours of Kepler's death have been greatly exaggerated (by me, in paragraph one. Sorry.), because while the telescope can't be aimed any more, it's still useful. The imaging functionality works fine, and with two remaining reaction wheels and a limited amount of thruster fuel left it's even got a bit of manoeuvrability. NASA has opened it up to the community to work out the best way to make use of what's left working; one proposal, for instance, involves heavily post-processing the images to remove drift caused by the lack of a third wheel.

There's hope for the mission yet, which is great, because as Ars Technica's John Timmer writes, there's a lot more to learn:

A longer mission would identify planets further from their host stars. To identify a candidate, Kepler needs to see it pass between Earth and the star the exoplanet orbits three times. The further out a planet is, the longer one orbit takes, so the longer it will need to do three passes. As such, the existing data is heavily biased toward planets that orbit very close to their host stars; this also means that most of the potentially habitable planets we've spotted are orbiting dwarf stars, which are dim enough that water can remain liquid close in.

In other words, we simply haven't looked long enough to detect planets in a habitable zone around energetic stars. We have a much better picture of the diversity of exoplanets, but it's far from a complete one.

Kepler. Photograph: Wikimedia Commons

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

Yu Ji/University of Cambridge NanoPhotonics
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Nanoengine evolution: researchers have built the world’s smallest machine

The engine could form the basis of futuristic tiny robots with real-world applications.

Richard P Feynman, winner of the Nobel Prize in Physics in 1965, once remarked in a now-seminal lecture that a time would come where we would “swallow the doctor”. What he meant, of course, was the actualisation of a science-fiction dream – not one in which a universal cure-all prescriptive drug would be available, but one in which society would flourish through the uses of tiny devices, or more specifically, nanotechnology. 

First, a quick primer on the field is necessary. Nanoscience involves the study and application of technologies at an extremely tiny scale. How tiny, you ask? Given that one nanometre is a billionth of a metre, the scale of work taking place in the field is atomic in nature, far beyond the observational powers of the naked human eye.

Techno-optimists have long promoted potential uses of nano-sized objects, promising increases in efficiency and capabilities of processes across the board as a result. The quintessential “swallow the doctor” example is one which suggests that the fully-realised potential of nanotechnology could be applied to medicine. The idea is that nanobots could circulate our bodily systems in order to reverse-engineer the vast array of health problems that threaten us.

It’s natural to be sceptical of such wild aspirations from a relatively young field of study (nanoscience unofficially began in 1959 following Feynman’s lecture “There’s Plenty of Room at the Bottom”), but associated research seems to be gaining widespread endorsement among prominent scientists and enthusiasts. Ray Kurzweil, Director of Engineering at Google, thinks a booming nanotechnology industry is crucial in the creation of a technological singularity, while futurist and viral video philosopher Jason Silva believes the technology will help us cure ageing.

The high-profile intrigue surrounding nanotechnology means that word of any significant developments is certain to stimulate heightened interest – which is why researchers’ achievement in building the world’s tiniest engine this month is so significant.

Reporting their results in the journal Proceedings of the National Academy of Sciences, the University of Cambridge researchers explained how the nanoengine was formed and why it represented a key step forward in the transition of the technology from theory to practice.

The prototype nanoengine is essentially composed of charged particles of gold, bound by polymers responsive to temperature in the form of a gel. The engine is then exposed to a laser which beams and heats the device, causing it to expel all water from the polymeric gel. The consequence of this is a collapsing of the gold particles into an amalgamated, tightened cluster. Following a period of cooling, the polymer then begins to reabsorb the water molecules it lost in the heating process, resulting in a spring-like expansion that pushes apart the gold particles from their clustered state.

"It's like an explosion," said Dr Tao Ding from Cambridge's Cavendish Laboratory. "We have hundreds of gold balls flying apart in a millionth of a second when water molecules inflate the polymers around them."

The process involved takes advantage of the phenomenon of Van der Waals forces – the attraction between atoms and molecules. The energy from these forces is converted into elastic energy, which in turn is rapidly released from the polymer. "The whole process is like a nano-spring," said Professor Jeremy Baumberg, who led the research.

Scientists have been tirelessly working towards the creation of a functional nanomachine – one which can effortlessly swim through water, gauge its surroundings and communicate. Prior to the research, there was a difficulty in generating powerful forces at a nanometre scale. These newly devised engines, however, generate forces far larger than any previously produced.

They have been named “ANTs”, or actuating nano-transducers. "Like real ants, they produce large forces for their weight. The challenge we now face is how to control that force for nano-machinery applications," said Baumberg.

In an email exchange with New Statesman about the short-term and long-term goals in bringing this engine closer to a practical reality, Baumberg said: “It allows us for the first time, the prospect of making nano-machines and nanobots. The earliest stage applications we can see are to make pumps and valves in microfluidic systems. Microfluidic chips are really interesting for synthesising pharmaceuticals, biomedical sensing and separation, as well as many other biochemical processes.

“But all pumps and valves currently need to be made with hydraulics, so you need a pipe onto the chip for each one, limiting strongly the complexity of anything you do with them. We believe we can now make pumps and valves from the ANTs which are each controlled by a beam of light, and we can have thousands on a single chip. Beyond this, we are looking at making tiny nanomachines that can walk around, controlled by beams of light.”

The embedding of nanobots into all facets of culture is still a long way off, and researchers will need to find a way of harnessing the energy of nanoengines. However, the prospect of one day seeing the fruition of nanorobotics is worth all the patience you can get. The tiniest robot revolution has just begun.