Before the Apollo 11 mission in July of 1969, NASA did not have a reliable way to transmit data generated in space back to Earth. And yet, everyone who was alive at the time probably remembers the footage of Neil Armstrong stepping out of the lander and making his famous “One small step for man” speech. That was possible because NASA set up both a dedicated communications network and a new broadcast standard to make sure that they could bridge the 238,000-mile gap between Earth and the moon for millions of people.
The network itself consisted of evenly-spaced antenna facilities placed around the world, with one in California’s Mojave Desert, one in Spain and two in Australia, so that one of them was always going to be facing the moon as the Earth rotated. But even then, bandwidth was a big problem because the network could only support very limited data streaming in the 4.5 MHz broadcast spectrum, and the majority of that was clogged with data being sent back from the lunar lander and orbiter, with not nearly enough left over for video. NASA compensated by changing the video signal from the standard 525 scan lines at 30 frames per second, which was standard for televisions at the time, to a much smaller format that was only 320 scan lines and 10 frames per second.
That made for a low resolution video, but millions of people watching around the world didn’t seem to mind. NASA has since restored and enhanced that original footage so that it’s now viewable in a little bit better detail, although it’s hardly anything approaching the HD quality of today’s photos and videos.
The high quality of photos and videos is one of the biggest challenges facing the Deep Space Network, which is what NASA now calls that system of antenna complexes. The original radio wave antennas used for the moon missions still exist, and have been supplemented by both smaller and larger antennas to increase bandwidth. And with all of the ongoing space missions, the network is extremely busy these days, which anyone can see on a special website that supports real-time monitoring.
As I was writing this column, I watched as one of the antennas based in the United States suddenly activated and started communicating with the Mars Odyssey Orbiter, currently sitting 312 million kilometers from Earth. That round trip signal took 34 minutes. Meanwhile, another antenna activated and started receiving data from the James Webb Space Telescope, sitting a mere 1.72 million kilometers from Earth, which made for a quick 11.4 second round trip. Elsewhere, in Madrid, one of the antennas there was constantly talking with the Korea Pathfinder Lunar Orbiter, receiving data from 371 thousand kilometers away. And the Deep Space Network is always busy. I’ve never seen a time when the antennas were idle.
And it’s no wonder because, despite the new antennas, there is never enough bandwidth. Consider the aforementioned James Webb Telescope. It can generate gigabytes worth of data every single day, and yet has to transmit it all back to earth at around 25Mbps. Some of the other spacecraft, which are much farther out, have even lower bandwidth speeds available. For example, I watched NASA’s Wind spacecraft transmit for over an hour at just 73 kilobytes per second. And poor Voyager 1, drifting 23.8 billion kilometers from Earth, had to transmit its data at an average of just 100 bits per second.
Until very recently, NASA did not have a good solution for building extra bandwidth into the Deep Space Network. Constructing more antennas helped, but only so much. In 2017, NASA began experimenting with laser communications systems, which seemed like a perfect replacement technology for radio waves since there is nothing much to get in the way of, or to interfere, with lasers in space.
And one part of that program, the TeraByte InfraRed Delivery — or TBIRD — system, just achieved an astounding success, transmitting experimental data originating in space onboard the orbiting Pathfinder Technology Demonstrator 3 Cube Satellite back to Earth using an infrared laser beam at 200 gigabits per second. At those speeds, some of those aforementioned transmissions on the Deep Space Network that took hours to complete could have finished in less than a minute, with some of them taking less than a second.
“This capability will change the way we communicate in space,” said Beth Keer, the mission manager for TBIRD at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Just imagine the power of space science instruments when they can be designed to fully take advantage of the advancements in detector speeds and sensitivities, furthering what artificial intelligence can do with huge amounts of data. Laser communications is the missing link that will enable the science discoveries of the future.”
It’s becoming unreasonable to try and transmit critical data from space that is collected by modern equipment, cameras and eventually human explorers, using technology like radio that was employed for space missions back in the 1960s. Instead, the infrared lasers of the TBIRD system could offer a better path, especially if the technology continues to improve, and can achieve success with even more data streaming from even farther out in deep space.
John Breeden II is an award-winning journalist and reviewer with over 20 years of experience covering technology. He is the CEO of the Tech Writers Bureau, a group that creates technological thought leadership content for organizations of all sizes. Twitter: @LabGuys