The NASA Cat Video Explained

You may have seen in the news last month that NASA beamed a cat video from space. It was all part of a test of new technology known as Deep Space Optical Communications. While the video went down in cat video history, the NASA technology used to transmit the first ultra-high-definition video from deep space also represented a historic advancement for space exploration – the potential to stream videos from the Moon, Mars, and beyond.

Read on to learn how this new technology will revolutionize space communications. Then, explore STEM learning resources that will get students using coding, math, and engineering to explore more about how NASA communicates with spacecraft.

Communicating with spacecraft across the solar system means sending data – such as commands, images, measurements, and status reports – over enormous distances, with travel times limited by the speed of light. NASA spacecraft have traditionally used radio signals to transmit information to Earth via the Deep Space Network, or DSN. The DSN is made up of an array of giant antennas situated around the globe (in California, Spain, and Australia) that allow us to keep in contact with distant spacecraft as Earth rotates.

Although sending transmissions using radio frequencies works well, advances in spacecraft technology mean we're collecting and transmitting a lot more data than in the past. The more data a spacecraft collects and needs to transmit to Earth, the more time it takes to transmit that data. And with so many spacecraft waiting to take their turn transmitting via the DSN's antennas, a sort of data traffic jam is on the horizon.

To alleviate the potential traffic jam, NASA is testing technology known as optical communications, which allows spacecraft to send and receive data at a higher information rate so that each transmission takes less of the DSN’s time.

The technology benefits scientists and engineers – or anyone who is fascinated by space – by allowing robotic spacecraft exploring planets we can't yet visit in person to send high-definition imagery and stream video to Earth for further study. Optical communications could also play an important role in upcoming human missions to the Moon and eventually to Mars, which will require a lot of data transmission, including video communication.

But why transmit a video of a cat? For a test of this kind, engineers would normally send randomly generated test data. But, in this case, to mark what was a significant event for the project, the team at NASA's Jet Propulsion Laboratory worked with the center's DesignLab to create a fun video featuring the pet of a JPL employee – a now famous orange tabby named Taters – chasing a laser. The video was also a nod to the project's use of lasers (more on that in a minute) and the first television test broadcast in 1928 that featured a statue of the cartoon character Felix the Cat.

The NASA project designed to test this new technology is known as Deep Space Optical Communications, or DSOC. It aims to prove that we can indeed transmit data from deep space at a higher information rate.

To improve upon the rate at which data flows between spacecraft and antennas on Earth, DSOC uses laser signals rather than the radio signals currently used to transmit data. Radio signals and laser signals are both part of the electromagnetic spectrum and travel at the same speed – the speed of light – but they have different wavelengths. The DSOC lasers transmit data in the near-infrared portion of the electromagnetic spectrum, so their wavelength is shorter than radio waves, and they have a higher frequency.

Since there are more infrared than radio wavelengths over a particular distance, more data can be sent over the same distance using infrared. And since the speed of infrared and radio waves is equal to the speed of light, this also means that more data can be sent in the same length of time using infrared.

As a result, DSOC’s maximum information rate is around 267 megabits per second (Mbps), faster than many terrestrial internet signals. At that high data rate, the 153.6 megabit cat video took only 0.58 seconds to transmit and another 101 seconds to travel the 19 million miles to Earth at the speed of light. Instead, if we had sent the cat video using Psyche's radio transmitter, which has a data rate of 360 kilobits per second, it would have taken 426 seconds to transmit the video, plus the same speed-of-light travel time, to get to Earth.

This kind of spacecraft communications isn't without its challenges. Accurately pointing the narrow laser beam is one of the greatest challenges of optical communications.

DSOC consists of a "flight laser transceiver" aboard the Psyche spacecraft – which is currently on its journey to study the asteroid 16-Psyche – and a receiving station on Earth. The flight transceiver is a 22-centimeter-diameter apparatus that can both transmit and receive signals. Its maximum transmitter strength is a low 4 Watts. For the December 2023 test, a 160-Watt beacon signal was transmitted to the DSOC flight transceiver by a 1-meter telescope located at JPL's Table Mountain facility near Wrightwood, California. This beacon signal was used by the Psyche spacecraft as a pointing reference so it could accurately aim the DSOC transceiver at the Earth receiving station – the 5-meter Hale telescope at Caltech’s Palomar Observatory near San Diego.

When the DSOC laser beam encounters Earth, it is much narrower than a radio signal transmitted from the same distance. In fact, the laser beam is only a few hundred kilometers wide when it reaches Earth, in sharp contrast with an approximately 2.5-million-kilometer-wide radio signal. This narrow beam must be pointed accurately enough so it not only intersects Earth, but also overlaps the receiving station. To ensure that the beam will be received at Palomar Observatory, the transmission must be aimed not directly at Earth, but at a point where Earth will be in its orbit when the signal arrives after traveling the great distance from the spacecraft.

Engineers will do additional tests of the DSOC system as the Psyche spacecraft continues its 2.2-billion-mile (3.6-billion-kilometer) journey to its destination in the asteroid belt beyond Mars. Over the next couple of years, DSOC will make weekly contacts with Earth. Visit NASA's DSOC website to follow along as NASA puts the system through its paces to potentially usher in a new means of transmitting data through space.

The DSOC project provides a wonderful opportunity to help students understand the electromagnetic spectrum and learn about real-world applications of STEM in deep space communications. Try out these lessons and resources to get students engaged.

• Image: Explaining the First Ultra-HD Video Sent From Deep Space via Laser
• Public Talk: A Day in the Life of the Deep Space Network
• Infographic: NASA Deep Space Network: Celebrating 50 Years of Communication and Discovery
• JPL Space Images: Deep Space Network

• DSN Now

• Deep Space Network Posters

• NASA: Deep Space Optical Communications (DSOC)
• NASA: Deep Space Network (DSN)
• NASA Science: Psyche Mission

• JPL News: NASA's Tech Demo Streams First Video from Deep Space via Laser
• JPL News: 5 Things to Know About NASA's Deep Space Optical Communications
• JPL News: Deep Space Network