Gyroscopes in space
Space is one of our last frontiers and could serve as both a resource for and catalyst of technological development. More and more corporations are interested in its potential, yet much of what makes all of their efforts possible is a humble technology - the gyroscope. Recently, scientists at the Lebedev Physical Institute in Russia showed off a tiny gyroscope that takes advantage of the atom-sized quantum sensor in diamond - the nitrogen vacancy (NV) center. Gyroscopes are devices that stay level and resists changes in orientation. If you have a spinning top for example, it can stay level even if the base that supports it moves. The gyroscope gained interest as a navigation tool when in World War I Elmer Sperry developed gyrocompasses which were used in warships. This technology leapt forward even further in airplanes for autopilot technology. The Hubble Space Telescope started using this technology in space which keep steering the telescope in precise directions for long periods, enabling the spectacular views we have seen from it of the Universe.
A quantum gyroscope
The NV quantum sensor has the ability to sense slow rotational speeds—in the range of tens of degrees per second. A new generation of ultrasensitive microchip gyroscopes could result from further developing this capability. Sub-atomic particles such as nuclei and electrons within atoms have a property known as spin. Unless acted upon by an outside force, a spin state will remain stationary, similar to the spin axis of a gyroscope. Therefore conceptually, a design for a gyroscope could be putting a spin in motion, letting it alone for a while, and then measuring it. To demonstrate the operation of the gyroscope, the researchers placed their diamond wafer on a rotating platform embedded in a magnetic field. The electron and nitrogen spins in an NV center are coupled through a light-mediated interaction. The team used a sequence of light pulses to set the nitrogen spins in an collection of NV- centers into one spin state. They then let the spins evolve for 2 milliseconds before reading out the new spin state using a second sequence of pulses. NV-centers fluorescences red light, and the intensity of the light can be used to calculate the rotation speed.
Potentially solar powered gyroscopes
This quantum gyroscope is particularly useful in space because it can be activated by an energy source that is easily accessible - solar energy. The NV-center has recently been demonstrated to be a quantum sensor that can directly use sunlight to obtain the energy it needs to operate by researchers at the University of Science and Technology of China. Typically, NV-fluorescence needs to be activated by green laser. The researchers filter sunlight using an optical band pass filter so that only green wavelengths shine through on the NV center to activate it instead of using laser.
Prospects for adoption of quantum sensors
With all these promising capabilities, the most accessible “closer to earth” use case of these quantum sensors is in satellites. Low Earth orbit (LEO) satellite internet constellations have seen accelerated adoption, with Starlink’s user base growing from less than 100,000 users in February 2021 to over 700,000 as of today. Such growth comes along with approx. 40,000 additional small satellites are required in space for Starlink alone. Additionally, Amazon has formed Kuiper Systems LLC to deploy satellites for the provision of broad-band internet and signed launch contracts for a total of 91 launches over the next decade in order to build out the entire constellation, now planned to contain 3,276 satellites with an overall contract value for these launches in excess of $10 billion.
To understand more about the use cases for quantum sensing technology in space, reach out to our technology specialist Fleming Bruckmaier!