WASHINGTON: Nasa announced on Dec 18 that it has successfully used an advanced laser communication system on a spaceship 19 million miles (31 million kilometers) away from Earth, to send a high-definition cat video. The 15-second video showcases an orange tabby named Taters, and is the first to be streamed from deep space. It demonstrates the possibility of transmitting higher-data-rate communications, which is crucial for complex missions such as sending humans to Mars.
The video was transmitted to Earth using a laser transceiver on the Psyche probe, which is on its way to the main asteroid belt between Mars and Jupiter to explore a mysterious metal-rich object. At the time of transmission, the spaceship was located at a distance 80 times greater than that between the Earth and Moon. The encoded near-infrared signal was received by the Hale Telescope at Caltech’s Palomar Observatory in San Diego County, and then sent to Nasa’s Jet Propulsion Laboratory (JPL) in Southern California.
Bill Klipstein, the tech demo’s project manager at JPL, stated, “One of the goals is to demonstrate the ability to transmit broadband video across millions of miles. Nothing on Psyche generates video data, so we usually send packets of randomly generated test data. But to make this significant event more memorable, we decided to work with designers at JPL to create a fun video, which captures the essence of the demo as part of the Psyche mission.”
Traditionally, space missions have relied on radio waves to send and receive data, but using lasers can significantly increase the data rate, by 10 to 100 times. The ultra-HD video took 101 seconds to send to Earth at the system’s maximum bit rate of 267 megabits per second – faster than most home broadband connections. Ryan Rogalin, the project’s receiver electronics lead at JPL, confirmed, “In fact, after receiving the video at Palomar, it was sent to JPL over the Internet, and that connection was slower than the signal coming from deep space.”
JPL provided a light-hearted explanation for choosing a cat video, citing the historic connection with television and the internet culture surrounding cats. The video, uploaded before the launch, features Tabby, the pet of a JPL employee, chasing a laser light on a couch, with test graphics overlayed, including Psyche’s orbital path and technical information about the laser and its data bit rate.
Laser transmission has been demonstrated in low Earth orbit and as far as the Moon, but the Psyche mission is the first time it’s been deployed in deep space. Aiming a laser beam from millions of miles away requires extremely precise “pointing”, a major technical hurdle engineering teams had to solve. The technology demonstration even needs to compensate for the fact that in the time it takes for light to travel from the spacecraft to Earth, both the probe and the planet will have moved – so the uplink and downlink lasers need to adjust for the change accordingly. – AFP
