Radio waves are still the main way to communicate with spacecraft, but that aging technology could soon get an upgrade that will allow faster data downloads from space. NASA is currently preparing to test out an X-ray communication system on the International Space Station.
The project, known as XCOM, will make use of equipment already onboard the ISS for different purposes. The Neutron-star Interior Composition Explorer (NICER) is currently perched on the outside of the space station, where it's scanning the cosmos for X-ray emissions coming from neutron stars.
But NICER is no one-trick pony. In 2017, NASA engineers demonstrated how the instrument could use data from millisecond pulsars as a kind of space-GPS, precisely calculating the position of the ISS to within 3 miles (4.8 km). It is this potential to pick up X-ray signals that makes it a good candidate for a receiver in an X-ray communication system.
To test the idea, at the other end NASA is using a specially-designed device called the Modulated X-ray Source (MXS). This device produces X-rays by first shining UV light onto a photocathode material like magnesium. That produces electrons, which are then accelerated into another material that in turn produces X-rays. Importantly, the MXS can be quickly switched on and off, encoding binary messages into X-rays that can be beamed to and deciphered by a receiver.
For the upcoming test, NASA installed the MXS on the outside of the ISS. There, it will beam X-ray messages over a space of 165 ft (50 m) to NICER, which will attempt to decode them. The message itself will be kept simple at first, the team says, to ensure that the device can pick up exactly what was sent. If that works, a more complicated message may be transmitted in a later test.
If all goes to plan, X-ray communication could eventually be used to beam data to and from a range of spacecraft. X-rays have much shorter wavelengths than radio waves or even laser communication systems, which are also in development. That means they should be able to pack more data into tighter beams, effectively allowing faster data transfer rates. And considering the long delay that can come from communicating with distant craft like New Horizons, anything that hurries the process along can only be a good thing.
Another potential advantage is that X-rays can penetrate the hot plasma sheath that normally cuts off radio communications when a craft is blasting through the Earth's atmosphere. X-rays could keep the crew in touch with ground control during this critical and intense period.
The XCOM tests are due to take place on the ISS in the next few months.
Source: NASA
