- Nov 29, 2023
NASA Will Test Deep Space Communications Lasers During Journey to the Metal World Psyche
When humans first set foot on Mars, communicating back to those on Earth will likely take some time. Given the distance between the two planets is at a minimum 33.9 million miles, or a maximum of 250 million miles depending on the orbit, it could take as long as 40 minutes using current radio technologies to receive and respond to a message.
And yet for a crewed mission as precarious as Mars, which NASA aims to reach by the 2030s, a lot can happen in those 40 minutes, which is why the space agency is interested in testing laser-based communications that can travel between planets faster.
A new generation of space communications
Navigational errors, changing weather patterns, and health emergencies, NASA officials say, are but a few of the factors that could be better mitigated through faster correspondence with mission control. What’s more, a reliance on radio waves limits the sheer amount of data that can be delivered from deep space — which means some information may never be transmitted. As humanity ventures farther into space, the logistical challenges of transmitting imagery and other demanding amounts of data will only grow, and radio will likely not be up for the challenge.
“Radio waves do have limitations,” Jeff Volosin, Acting Deputy Associate Administrator for NASA’s Space Communications and Navigation (SCaN) program, told reporters on Wednesday (September 20). “Just like higher bandwidth internet on Earth, we’re looking to increase the speed … and amount of data we can send down to Earth.”
Volosin was speaking at a NASA press conference about Deep Space Optical Communications (DSOC) technology, which is loaded onto NASA’s upcoming Psyche asteroid mission so the space agency can test it out. He explained how laser communications could radically reduce Mars communications, while also allowing high-definition imagery to be sent to Earth from the lunar surface “in real time.”
The $1.2 billion NASA Psyche mission, which was originally scheduled for October of last year, constitutes the first-ever visit to a massive metallic asteroid, located in the Mars-to-Jupiter asteroid belt.
Anticipated to arrive at its target, which has an average diameter of 140 miles, by July 2029, the craft will begin transmitting information shortly after launch. It will useboth primary radio antennas, which lean on the existing Deep Space Network (DSN) — a series Earth-based ground stations and orbiting satellites that act at relay stations — as well as the more exploratory DSOC technology.
The latter will represent another a first: Humanity’s initial laser communications from deep space. The DSOC demonstration is expected to continue for two years, with the possibility of extended-mission opportunities.
If successful, the tech will encode information in photons through narrow pulses of light, increasing data transfer rates up to 100 times more than radio signals, and transmitting up to 1,000 times farther than existing laser trials between the Earth and the Moon.
The further the laser travels, the weaker it becomes, officials explained, which correspondingly requires sensitive detectors that employ an interesting concept: photon-counting cameras.
As an analogy, think of an especially sophisticated morse code, with receivers that can count the arrival of photons down to the sub-nanosecond level — less than a billionth of a second.
Because of the tremendous distance between transmitter and receiver, NASA team leads at Wednesday’s press conference expressed caution.
“When you’re pushing the envelope like we’re doing here, you’re going to try things that haven’t been done before,” said Tanya Laughinghouse, program manager for NASA’s Technology Demonstration Missions. “So even if the technology doesn’t perform as expected … you’re going to learn by looking at that data.”
“It’s like trying to hit a dime from a mile away, while the dime is moving,” said Abi Biswas, DSOC project technologist at NASA’s Jet Propulsion Laboratory (JPL). The tech’s proof of concept, however, is somewhat long-established.
About a decade ago, NASA’s Lunar Laser Communication Demonstration (LLCD) made history by transmitting data from lunar orbit to Earth, with a download rate more than six times faster than existing radio systems — a capacity that could one day be applied for non-space related use in fields like spectroscopy, enhanced medical imaging, pharmaceutical development, and environmental management.