If you want to know where you are in space, it’s best to bring a map. But it’s more complicated than riding shotgun on a family trip.
Spaceflight beyond Earth’s orbit is usually done by mission control. A series of global radio transmissions, known as the Deep Space Network, allow crews to check in on space equipment and improve their navigational conditions. The system works, but it could be better. What if a spacecraft could choose its own location, without having to call home? That’s been a dream of aeronautical engineers for a long time, and it’s about to come true.
Pulsars are the key.
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Pulsars are rotating neutron stars – the very dense cores of massive stars that have exploded – that emit jets of electromagnetic radiation from their cores. They act as beacons that regularly wash radio messages to Earth in a reliable rhythm. The first pulsar was discovered by Jocelyn Bell in 1967 and was named LGM-1 (Little Green Men 1), because until the discovery of the second, extraterrestrial intelligence could not be ruled out. and the cause of the pulsar. Now, we know about thousands, and we are convinced that they are natural phenomena.
Because pulsar beams are predictable, they can be used for triangulation, where a spacecraft receiving high pulsar signals must know its position in space up to a distance of 5 km -10.
The theoretical basis of this approach is solid. So much so that the golden records (time capsules of Earth and human culture) that were attached to the side of the Voyager and Pioneer spacecraft in the 1970s clearly showed the position of our sun relative to the 14 pulsars, just in case the LGM stumbles. spacecraft and they want to visit us here on Earth. We have given them instructions.
But if pulsars are such an effective means of navigation, why haven’t they been used yet? After all, studies on this topic have been ongoing since the 1970s, when the Jet Propulsion Lab first looked at the prospect.
With all space activities, one of the main factors is weight. It costs a lot of money to put things in place, so every kilogram in every car has to be counted. Any viable pulsar navigation system would have to be very small, and very light, otherwise valuable scientific equipment or fuel for navigation would have to be cut to do it. This is a significant obstacle to designing an effective pulsar navigation system. Pulsars are usually very faint sources, making them difficult to detect without powerful (heavy) instruments, especially radio waves.
Fortunately, there is a solution that can make it possible, and that is to use an x-ray telescope instead. These can be smaller and lighter, and still pick up pulsar signals like a radio antenna.
In recent years, astronomers have been working to improve the way the spacecraft deals with pulsar signals, to increase the efficiency of the system and reduce the chances of errors. The hardware has even been tested on the International Space Station, where the NICER/SEXTANT washing machine-sized experiment has successfully tracked the station’s orbit using pulsars since 2018. Now, teams are working to develop more efficient equipment for deep space operations. . An announcement published on ArXiv last month describes a prototype walking unit called PODIUM, which will weigh only 6kg, consume 20W of power, and fit into a box 15 cm by 24 cm by 60 cm. The first results are promising. PODIUM should be able to determine the aircraft’s position within about 10km, using X-ray signals from the array of pulsars.
Soon, these images may become reality, guiding the next generation of research into their destination. They may also guide human spaceflight, and NASA’s upcoming Lunar Gateway space station is expected to be equipped with a pulsar navigation system. We’re about to navigate deep space: like GPS, but for the galaxy. Now, if only we had warp drives…
Deep Space Network
Feature Image: A pulsar with gravity lines depicted. Credit: NASA.