Smart dust could put telescopes in a spray can
Good things come in small packages – and sometimes in aerosol cans. To prove this, researchers at the Rochester Institute of Technology (RIT) and NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California are working on technology for a future generation of space telescopes that may one day see the giant instruments replaced by swarms of particles that are deployed from a can and herded into place by laser beams.
Space telescopes have revolutionized our view of the Universe, from sending back spectacular images of distant objects on the other side of the galaxy, to discovering exoplanets that may harbor extraterrestrial life. Unfortunately, telescopes such as the Hubble and the James Webb are incredible feats of engineering where only a fraction of the mass is used for the actual collection of light to form images. Instead, most of the device is dedicated to nothing more than supporting the reflective surfaces – which is odd because that surface needs to be only a molecule thin to be effective.
Part of NASA’s Innovative Advanced Concepts Program's Orbiting Rainbows project, the team led by Grover Swartzlander, associate professor at RIT’s Chester F. Carlson Center for Imaging Science and the JPL's Marco Quadrelli aims at replacing the current constructions of tubes and metal alloy braces with dust – smart dust, that is.
The idea is that instead of the telescope being a single heavy structure, it's broken up into a set of smaller mirrors. It's similar to the approach used on Earth, where gigantic mirrors that take years to grind have given way to arrays of smaller mirrors working in concert. The difference with the smart dust approach is that the scientists are taking it to its logical conclusion by replacing the one big mirror with countless thousands of mirrors the size of tiny dust particles.
"Our motivation is to make a very large aperture telescope in space and that’s typically very expensive and difficult to do," says Swartzlander. "You don’t have to have one continuous mass telescope in order to do astronomy – it can be distributed over a wide distance. Our proposed concept could be a very cheap, easy way to achieve large coverage, something you couldn’t do with the James Webb-type of approach."
The approach is very simple in concept. Particles of photopolymers coated with a metallic film are released into space along with an optical package and a set of laser generators. The lasers under computer control shoot at the particles and herd them into a mirror, which reflects light back to the instrument package. Moving the scope to aim it a desired target is a bit like watching a flock of birds as the lasers collapse the mirror, then reform it again pointing in another direction.
Not only is such a system potentially cheaper than current space telescopes, but it also opens the door for gigantic telescopes thousands of kilometers in diameter. However, Swartzlander says that the technology is still in its infancy and may not be practical for another 20 or 30 years.
At the moment, the team is working on the two most basic problems with the smart dust telescope. The first is learning how to actually herd the dust motes using lasers, and the second is how to develop computer algorithms that can turn the inherently fuzzy picture of such a telescope into something useful.
"Our goal at this point is to marry advanced computational photography with radiation-pressure control techniques to achieve a rough image," Swartzlander said. "Then we can establish a roadmap for improving both the algorithms and the control system to achieve 'out of this world' images."