With the help of a new laser ranging system, we might soon be able to send a laser beam to Mars--and hit our target within a millimeter. Scientists at NASA's Jet Propulsion Laboratory at the California Institute of Technology have developed a new kind of high-precision laser system that can span interplanetary distances with millimeter accuracy.
Most current laser technology uses passive ranging, meaning it bounces light off a reflector. This works for relatively short distances, like from the Earth to the Moon--238,900 miles--but at longer stretches, the laser's signal peters out. Depending on where Mars and Earth are in their respective orbits, the distance between the two is between about 34 million and 249 million miles.
The new system doesn't make the lasers themselves more powerful. Rather, it increases the ability to detect laser pulses over long distances by using active, synchronised receivers on both ends that can send and receive laser pulses. "The key is to have a very sensitive receiver and a method to pick out the 'signal' photons from all the background light," one of the scientists, Kevin Birnbaum, told Phys.org.
So far, the system has only been field-tested on Earth, but its creators hope to test it across greater distances soon. "In principle, this approach could be scaled up to any interplanetary distance by increasing the size of the telescopes," Birnbaum said. "We calculated that ranging from Earth to Mars or Jupiter should be achievable with quite modest telescopes of 1 meter in diameter on Earth and 15 centimeters on the spacecraft."
High precision lasers with interplanetary range could help scientists more accurately measure gravitational fields and determine the make-up of the planetary cores. Gravity tests with the new laser system could "help to quantify the apparent acceleration of the expanding universe, the possible existence of extra dimensions, and the reconciliation of quantum mechanics with gravity," the researchers write in their paper describing the system.
The study appears in Applied Physics Letters.
Quantum entanglement would be faster. I can see a host of reasons for these lasers, as far as telemetry goes, but I think using them for data transfer will be obsolete sooner than this tech is ready for wide scale use. Not to mention that atmospheric obstacles can be unpredictable and make using lasers a temperamental thing. No doubt these lasers will be expensive to operate as well. Thank you Popsci for leaving out all the details on the types of lasers used, the power of the lasers, the systems that receive the.... nevermind:
"Birnbaum explained that the laser itself is not any more powerful than those in use today.
"The lasers themselves do not need to be very powerful," he said. "Commercially available lasers have enough pulse energy, and the light intensity as it leaves the transmitter can be low enough that it is even eye-safe. The key is to have a very sensitive receiver and a method to pick out the 'signal' photons from all the background light."
The scientists tested the approach with lab experiments and field testing on Earth. They measured deviations in actual distance of no more than 0.14 mm, well below the goal of 1 mm precision. Although fluctuations due to atmospheric turbulence in Earth's atmosphere will add a small amount of error, the scientists think that this error can be limited to less than 1 mm.
The biggest challenges to realizing the long-range, high-precision laser include synchronizing the transceivers and overcoming a background of stray light. The researchers plan to overcome these challenges by using a new synchronization scheme involving interplanetary laser communications, along with using short pulses with a low repetition rate. In the future, they'd like to test the system on a somewhat larger scale.
"Having demonstrated this technique in the lab and between two terminals in the field, we'd like to next perform ranging between a transceiver mounted on an airplane and one on the ground," Birnbaum said. "Then we could move on to ranging between a ground terminal and a spacecraft."
This giant leap in laser ranging could have many applications. One of the first may be to solve the puzzle of the composition of Mars' interior. Since the 1970s, scientists have been trying to find out if the interior is liquid or solid, but their attempts have been thwarted due to limitations of RF ranging precision. If the new laser ranging approach were applied to a future mission to Mars, particularly Mars Landers, it has the potential to resolve this open question.
Interplanetary precision laser ranging could also enable new tests of fundamental physics, including tests of the equivalence principle, the apparent acceleration of the expanding universe, and the possible existence of extra dimensions. The laser system could also enable tests of gravity, which could lead to the discovery of a violation or extension of general relativity, or the presence of an additional long-range interaction.
Finally, the laser system could enable various tests to be performed on the planets and other solar system bodies, which could shed light on their evolution, atmospheres, oceans, and ring material. These measurements are currently based on RF ranging techniques, which have limited precision."
"Do not try and bend the spoon. That is impossible. Only try and realize the truth - there is no spoon."
Ok, lets hook unit up and power it by a flux compactor and point it towards the Orion Belt and call our alien overlords back home!
I was wondering if this technology would be able to be used for communications in future space exploration? If we ever send people to the Moon or even Mars would this type of tech. be useful?
YES my point exactly and this is why we should call the ancient aliens that visited us, who built all the pyamids long ago and the monolithic structures.
"Point these lasers towards the Orion Belt and start broadcasting HELLO!"
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