What kind of download speeds can you expect on the International Space Station?
What about on Mars? Well, as you can imagine, it's not great.
NASA communicates with its rovers on Mars and all of its deep space probes using the
NASA Deep Space Network, or DSN, which unfortunately has some pretty serious limitations, due to
being both based on radio waves and established in 1963.
We'll see if you're still spry when you turn 60.
To overcome these challenges, NASA's Jet Propulsion Laboratory is working on a new system
called Deep Space Optical Communications, or DSOC, which is a laser system that might
just be a game changer for interplanetary communication.
And yes, they've already used it to send a cat video.
Before we get into that, though, let's talk about the old system that DSOC needs to be
better than. In many ways, the DSN is a scientific and engineering marvel.
It uses three antenna arrays in California, Spain, and Australia in order to ensure coverage
of the entire sky, and each array is located in a bowl-shaped mountainous area to shield
it from as much radio interference as possible. The DSN uses a small subset of relatively high-frequency radio waves that can easily
escape Earth's atmosphere, rather than bouncing off the ionosphere and coming right back,
which can happen with low-frequency radio waves like those used for AM radio.
Radio waves, being a form of electromagnetic radiation, move at the speed of light, so
using lasers wouldn't really speed up communication in the strictly literal sense.
They would, however, massively increase efficiency and bandwidth.
The longer an electromagnetic wavelength is, the less information it can carry every second.
Unfortunately, radio waves are the longest of the electromagnetic spectrum, and thus
have the lowest carrying capacity. The lasers that desoc will use are in the near-infrared region, making them comparably
tiny, and therefore allowing a much higher bandwidth.
This means that an important communication from a nearby planet like Mars would take
basically the same amount of time to physically reach Earth, between 3 and 22 minutes depending
on where the two planets are in their orbits. But 10 to 100 times more information could be sent every second.
A data package that would otherwise take days or months could instead be downloaded
in a matter of hours. The hardware necessary to communicate via lasers is also lighter and more compact than
comparable radio systems, meaning that it's easier to fit onto a relatively small probe
or rover without excessively increasing the fuel needed to escape Earth's gravity well.
You know, another problem with radio waves is that they tend to spread as they're transmitted.
And that's not a problem when you want them to go everywhere, like with a television broadcast,
but it means that the signal quickly becomes very weak once it travels any significant
distance from its original source. And unfortunately, almost everything in space is very, very far away.
With lasers, you still need to account for signal interference and distortion over long
distances, but a coherent beam of energy is going to maintain its strength for longer.
Think of it like the difference between a shotgun blast and a shot from a sniper rifle.
The energy is more focused and it goes much farther. But infrared lasers do have physical limitations that radio waves don't.
They require far more precise aim, and much like visible light, they can't travel through
opaque objects. That's not a major problem, though, seeing as space is mostly empty.
So when exactly will we be sending those cat videos?
And what kinds of speeds can we expect within our own solar system?
We might be able to send and receive laser transmissions, feline or otherwise, from as
far as our solar system's inner asteroid belt as soon as 2029.
That's because we've actually been developing the technology needed to catch Mars' telecommunications
up to the 21st century for several decades.
Scientists made their first major breakthrough with extraterrestrial laser communications
in 1968, when they proved that the Surveyor 7 moon lander could detect lasers originating
on Earth. In 1995, the Japanese Space Agency was able to establish two-way laser communication with
its ETS-6 satellite at an astounding 1 megabit per second.
By 2001, we had achieved laser communication between satellites, and by 2013, NASA used
lasers to send an image of the Mona Lisa to a satellite orbiting the moon.
The technology has progressed to the point where we can easily transmit data between
Earth and low Earth orbit at not just megabits, but even many gigabits per second.
On October 13th, 2023, NASA launched the Psyche Mission, a spacecraft bound for the
asteroid 16 Psyche, which sits in the asteroid belt between Mars and Jupiter.
That mission will also be an important test for the technology behind DSOC, as the Psyche
spacecraft will encode its data and send it back to Earth using infrared lasers.
The Psyche mission won't arrive at its destination until 2029, but it's already made one successful
test of the new communication system. On December 11th, 2023, from over 19 million miles away, the spacecraft sent back an ultra-high-definition
video of an orange cat, reportedly named Tater, playing with the dot of a laser pointer.
The hope is that Psyche's DSOC will be able to send data back at 2 megabits per second
even after it reaches its destination, far beyond Mars, demonstrating the viability of
laser communication even in the farthest reaches of the solar system.
Wealthy. Inner solar system for now. But we're coming for you, Neptune.
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Like this one, on the world's longest wireless internet range.
There may be lasers involved. I haven't seen it. I don't know.