China may have just solved one of the big challenges of deep space travel
There are a lot of challenges involved when people attempt to “boldly go where no one has gone before.” Gravity, radiation, weightlessness, space madness and of course the infinite expanse of the universe are all issues which need to be resolved before we can emulate Jean Luc Picard and his crew. But there is hope that at least one of these challenges is about to be solved.
What’s stopping me from boldly going to space?
Currently the only way a spacecraft knows where it is is by using the Deep Space Network, a series of antennas located in California, Australia, and Spain. For spacecraft that want to go further and further away from earth, a new system is necessary — and x-ray navigation could be the answer.
And what is X-ray navigation?
“In a nutshell, it is the cosmic equivalent of GPS,” John Pye, the manager of the Space Research Centre at the University of Leicester, told VICE News.
Last week the China National Space Administration launched the X-ray Pulsar Navigation 1 satellite. The satellite has a new type of navigation system on board which no longer relies on earth-based signals to show where it is in space. Nasa plans to launch a similar satellite next year to the International Space Station.
China believes the new system, if it works, will help accelerate space exploration plans, which include a manned mission to the moon, a Martian lander and deep space travel. As Nasa told VICE News: “At some point, leaving the solar system, it is the only game in town.”
How does it work?
On earth, if you want to know where you are, you use GPS. This works thanks to satellites in orbit around the earth which connect to your smartphone or SatNav to triangulate your exact position on the planet.
With the x-ray navigation system, GPS satellites are replaced by pulsars — highly magnetized, spinning stars — which send pulses of x-ray energy to spacecraft housing telescopes designed to read those emissions. These measurements are then fed into another algorithm to find out a spacecraft’s position.
“The concepts our research have developed are designed to support an autonomous spacecraft operation eventually traveling someday to a distant star system,” Suneel Sheikh, an associate fellow of the American Institute of Aeronautics and Astronautics told VICE News.
Pulsars are compact stars that emit a regular beam of energy. ”They are spinning, and it’s a bit like a lighthouse beam going round,” Pye said. “If you are in the path of the beam you see a flash every time the pulsar rotates.”
But pulsars send pulses of energy much more regularly. The fastest pulsars, called millisecond pulsars, spin up to 1,000 times per second, meaning that a satellite tuned to receive its emissions can get very accurate measurements to help locate itself in space.
Pulsars are key to this new navigation system but, unlike GPS satellites, we cannot simply launch more if we need them. There are currently a few thousand known pulsars across our galaxy, located between 100s and 1000s of light-years away. But only around 100 of these known pulsars emit the needed x-ray emissions and just 30-40 have “well determined pulse characteristics” according to Pye.
“Of those, unless you build a really big telescope, which would be difficult to launch, then you are down to five or 10 that are bright enough,” Pye explained.
How many pulsars are needed?
In order to get your position in space, a satellite using this system would also need to have an accurate timepiece — such as an atomic clock — and be able to receive emissions from at least three pulsars.
What are the benefits of x-ray navigation?
The benefits of this new system are two-fold. Firstly, it will be cheaper to run, since you no longer need to tie up resources on the ground like deep space network radio dishes.
The second benefit is that it gives spacecraft autonomy from earth (at least in terms of navigation) which makes deep space or interstellar space flight at least one step closer.
In the nearer term, the benefits will likely be confined to our own solar system. “Having at least a semi-autonomous system makes things easier in terms of navigation as you get to the outer solar system, the outer planets like Jupiter, Saturn and beyond,” Pye says.
A new space race?
While some might see this as a major victory for China, Nasa told VICE News that this may not be the case. “We have not heard about any of the detail of the XPNAV-1 payload. To our knowledge, China has not launched any X-ray instrument to date before this one, so we do not know what they are using or how well it will work.”
Sheikh explains that any Chinese success is good for the world’s understanding of space. “As these demonstration missions are intended to provide validation of existing concepts and past experiments, both will provide valuable information with respect to instruments and algorithms for processing pulsar signals. This continued research will greatly support future humankind space exploration.”
So that’s sorted then?
Well not quite. This will all remain theoretical until the Chinese satellite can prove the system works. Even if the x-ray navigation system is shown to work, there are still multiple other issues needing to be solved before you dream of joining Captain Picard’s mission “to explore strange new worlds, to seek out new life and new civilization.”
Cover: ASSOCIATED PRESS