(ORDO NEWS) — Spacecraft navigation beyond Earth orbit is typically handled by mission control.
A series of radio communications networks across the planet allow operators to communicate with space probes and update their navigational status.
What if a spacecraft could autonomously determine its position without referring to the Earth? This has been a longtime dream of aerospace engineers and is close to being realized.
Pulsars are spinning neutron stars, the superdense cores of exploded supergiant stars that emit blasts of electromagnetic radiation from their poles.
They act as interstellar beacons that constantly transmit radio signals to Earth at an unchanging rhythm. The first pulsar was discovered by British astrophysicist Jocelyn Bell in 1967.
Because pulsar beams are so predictable, they can be used for a kind of triangulation whereby a spacecraft receiving overlapping pulsar signals should be able to determine its position in space to within 5-10 kilometers.
The theoretical basis of this method is quite strong.
So much so that the records (time capsules of Earth and human culture) that were attached to the board of the Voyager and Pioneer spacecraft in the 1970s graphically indicated the position of the Sun relative to 14 pulsars, in case any LGMs stumble on a spaceship and want to visit us here on Earth.
But if pulsars are such an efficient form of navigation, why haven’t they been used yet?
Research on this subject has been ongoing since the 1970s. It was then that the Jet Propulsion Laboratory first began to study the prospect of using this method of navigation.
In all space missions, one of the key parameters is weight. Launching objects into space is expensive, so every kilogram on the vehicle must be counted.
Any workable navigation system would need to be very small and very light, otherwise important scientific instrumentation or propulsion fuel may have to be cut back to compensate.
This is a major obstacle to the development of a viable pulsar navigation system. Pulsars are usually incredibly weak point sources, making them difficult to detect without powerful (heavy) equipment.
Luckily, there is a solution that can make this possible, and use an X-ray telescope instead. They can be smaller and lighter, and still pick up pulsar signals just as well as radio antennas.
In recent years, astronomers have been working to improve the way spacecraft process pulsar signals, improving system efficiency and reducing error margins.
The equipment has even been tested on the International Space Station (ISS), where a machine the size of a washing machine has been successfully tracking the station’s location using pulsars since 2018.
Teams of engineers are now working on developing even more compact equipment for deep space missions.
arXiv describes a prototype navigation device called PODIUM that will weigh just 6kg, consume 20W of power, and fit in a 15cm x 24cm x 60cm box.
Early results are already promising. PODIUM should be able to locate the spacecraft to within 10 km using X-ray signals from a catalog of pulsars.
Soon these prototypes may become real. They will be able to guide the next generation of space probes to their destination.
They will likely also guide passenger spacecraft, and NASA‘s upcoming Lunar Gateway space station is expected to feature such a navigation system.
Now, if we still had warp drives, we could solve the problem of overcoming the vast space in the Universe.
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