On July 21, a series of instructions sent by NASA to the Voyager 2 space probe caused its antenna to deviate by about two degrees by mistake. As a result, the antenna was misaligned with Earth and contact with the ship was lost. Right now, although Voyager 2 continues to operate and transmit data, it can’t reach NASA’s network of tracking antennas around the world. And the probe also can’t receive communications, so it can’t be sent a sequence of instructions to correct the problem.
Yesterday, when it got dark, a ray of hope. NASA picked up a signal – “kind of like hearing the spacecraft’s heartbeat” – that confirms Voyager 2 is still transmitting. The agency’s expectations now center on the proper functioning of the antenna reorientation mechanism, a procedure that Voyager 2 performs periodically and autonomously several times a year. According to NASA, the next activation of the process will take place on October 15.
The twin Voyager probes are humanity’s most distant spacecraft. Launched into space in 1977 two weeks apart, Voyager 1 and Voyager 2 are 23,900 and 19,900 million km from Earth, respectively. Voyager 1 communications take 22 hours and 12 minutes to reach our planet, and those of its twin, 18 hours and 28 minutes.
After nearly 46 years, the Voyagers are still operating and sending data back to Earth. Approximately half of the ten scientific instruments at their disposal are operational, and from the measurements they make it is known that both ships have entered what is known as the interstellar region, the space where the solar wind and the field magnetic field of our star are no longer dominant.
NASA forecasts indicate that Voyager 1 has enough energy to continue operating until 2040, and in the case of Voyager 2, reserves are expected to last until 2034.
The Voyager missions represent one of the greatest achievements of space exploration. Its main objective was the exploration of the four large gaseous planets of the solar system, taking advantage of a strange alignment that occurs every 175 years and that allowed it to jump from one planet to the next in low-consumption trajectories. This jump mechanism is called gravitational assistance, and it takes advantage of passing close to a planet to correct the trajectory and accelerate it towards the next target, as if it were a game of billiards.
To design the mission and take advantage of planetary alignment, NASA engineers analyzed more than 10,000 possible orbits for Voyager. Eventually, the chosen trajectories took Voyager 1 to Jupiter (including a close pass by Ion, one of that planet’s most spectacular moons), then to Saturn and its largest moon, Titan. and finally towards the far reaches of the solar system.
For its part, Voyager 2 visited Jupiter, Saturn, Uranus and Neptune consecutively before heading, also, towards the outermost regions of the solar system. In this way, it has become the only mission that, for the time being, has approached Uranus (January 1986) and Neptune (August 1989).
The margins of error allowed by the Voyager trajectories were tiny. For example, the first pass by Jupiter, a planet located 800 million km away, had to be done with an accuracy of 100 km.