I'm creating a short film celebrating Voyager 1's progress out of our Solar home. I would like to be as accurate as possible.
Question: What is the craft's normal orientation as it travels? Is the main dish toward the Earth, which makes sense to me, for communications? Or is there some other orientation?
TY, very much for any answers. Also TY, NASA for supplying a blend file of Voyager 1. Love you guys!
NASA communicates with both Voyagers just about every day, even now. Changing the attitude of the spacecraft uses fuel, so that is done as little as possible. So the entire interstellar mission has been flown with the antenna pointed at Earth.
The linked article indicates that in November 2023, they uploaded a patch for the attitude control system: by allowing more deviation in the antenna pointing (1º), they will have fewer thruster firings, in an effort to increase the longevity of the thrusters.
During the cruise phases between planets, the antenna was also kept pointed at Earth. During encounters, the spacecraft were occasionally rotated to a different attitude. They did this during the Uranus and Neptune encounters to help point the cameras at their targets, and during the Saturn encounter the ring plane crossing was done with the dish facing forward.
For the Saturn and Uranus encounters, a technique was developed to use the spacecraft's gyroscopes to smoothly execute image motion compensation (IMC) turns to track selected targets during the near-encounter phase. Communications are broken off during IMC, since Voyager's antenna is moved off of Earthline, and all IMC data must be recorded.
A new capability termed nodding image motion compensation (NIMC) has been developed for the Neptune encounter. NIMC permits the spacecraft to remain nearly Earth-pointed while turning slightly, shuttering a frame, and turning back to Earth-point. This means the pictures can be transmitted directly to the ground in real-time without the need for intermediate storage on the digital tape recorder (DTR). The nodding motion of the spacecraft is accurately controlled by precisely calibrating the small attitude-control thrusters, and then programming the onboard computer to fire the thrusters a predetermined number of times as needed to turn the spacecraft at the desired IMC rate.
For example, during the Uranus encounter:
As Voyager 2 passes behind Uranus (as seen from Earth), the spacecraft's high gain antenna will be moved in a series of eight straight line segments to closely track the outline of the planet.
But even during the encounters they kept the dish pointed at Earth as much as possible so they could gather more data: the capacity of the tape recorders was limited, so some data was sent directly to Earth instead of being stored onboard.
