Once a year, we approach NASA’s Voyagers: here’s why

Once a year, we approach NASA’s Voyagers: here’s why

both from nasa The Voyager spacecraft is on a one-way trip through interstellar space on its way out of the Solar System.

The pioneering missions launched in 1977 to send two probes to the outer Solar System, collectively observing Jupiter, Saturn, Uranus, and Neptune. Voyager 1 successfully completed a flyby of Saturn in 1980 and rose above the plane of the Solar System, while Voyager 2 took advantage of a rare alignment to get a close-up look at Uranus and Neptune, the only spacecraft to do so. now, though scientists are clamoring for a deeper dive into Uranus.

The spacecraft, still operational by chance, continues to send back data. But every year an orbital quirk arrives. Although the Voyagers are rapidly leaving our Solar System, there is a period when the spacecraft are a little closer to us once a year for a few months.

For example, distance data from NASA’s Jet Propulsion Laboratory shows that Voyager 2 was 130.05518 astronomical units (Sun-Earth distances) from our planet on February 20. However, the spacecraft will be at 129.72179 astronomical units (Sun-Earth distance) on June 2 before moving away again.

The reason is the motion of the Earth rather than the spacecraft: “When the Earth is on the same side of the Sun as the Voyagers, it’s closer,” says Candice Hansen-Koharcheck, a senior scientist at the nonprofit Planetary Science Institute. profit. Reverse. “When [Earth] it’s on the opposite side of the sun from the Voyagers, that’s when they’re furthest away.”

Hansen-Koharcheck said the best way to figure that out is to take a piece of paper and draw a dot in the middle that represents the Sun. Then draw a line from the Sun to the edge of the paper; that’s one of the Voyagers moving into interstellar space.

Then draw a circle around the Sun. That circle represents Earth’s orbit. As the circle shows, there are times in our planet’s 365-day journey around the sun when we find ourselves on the opposite side of the departing Voyagers, yielding the greatest distance.

Both Voyagers are moving away to points beyond the Solar System in different directions. POT

How long will the Voyager probes last?

Both Hansen-Koharcheck and a representative from NASA’s Jet Propulsion Laboratory noted that the increased time distance between the spacecraft and our planet has no impact on communications or the mission. The Deep Space Network, an array of antennas around Earth, controls communications for the nuclear-powered Voyagers.

“It doesn’t make much of a difference to the Deep Space Network because Earth is now so far away from the Voyagers,” says Hansen-Koharcheck. While there would be a slight difference in signal strength, both Voyagers have enough power to continue transmitting for now.

The two spacecraft will celebrate 45 years of space operations this summer. This is two to four times the lifespan of a typical solar-powered spacecraft. But this situation will not continue forever, the JPL representative said.

“Both spacecraft are dealing with dwindling power supplies because their onboard RTGs [radioisotope generators] continue to decline, reducing their power output by about 4 watts per year,” says Rep. Reverse in an email.

“For the past several years, the team has been shutting down heaters and other subsystems that are not critical to spacecraft operation or science instruments,” they say. “That has included some science instrument heaters, but surprisingly the instruments are still working. The engineering team has really done an amazing job keeping these two spacecraft running.”

NASA edited this composite to show the view as it leaves the area around Triton. NASA/JPL-Caltech

Will NASA ever send a probe to Neptune?

Hansen-Koharcheck and Heidi Hammel, now vice president of science for the Association of Universities for Research in Astronomy (AURA), were part of the Neptune imaging team when Voyager 2 made its historic flyby in 1989. (Hammel was not available for an interview before the deadline for this article.)

“She [Heidi] he was the person who knew the most about Neptune, seen through a telescope,” says Hansen-Koharcheck, who was working at JPL at the time, of Hammel’s contribution. “So Brad Smith, the head of the imaging team, invited her to come.”

Hansen-Koharcheck’s job was to command Voyager 2’s slow-scan color television camera to take images of the planets and schedule the spacecraft’s imaging observations. She recalled that the spacecraft’s view of Neptune began to improve in ground-based observations about six to eight months before the spacecraft reached its closest point on August 25, 1989, which meant several intense months of work for the imaging team.

“Every afternoon, Heidi and I would have this little date, so to speak, where she would walk over from her office. She and I would go to what was essentially a broom closet, but it was basically a place where you didn’t have a window. You can look at the screen and see the images,” says Hansen-Koharcheck.

“We recovered the data of the day. Heidi kept all the notes and I ran the computer. The two of us were the first to see things like the Great Dark Spot. [storm] and begin to measure its rate of rotation from the images… and observe the different circulation of the different latitudes of the atmosphere”, he adds.

Hansen-Koharcheck says the Neptune encounter and the chamber staff’s teamwork produced “wonderful times” and says she’s hopeful that decades of community lobbying will help produce a new mission to Neptune.

But so far, the deep blue planet has yet to receive another try. 2021 saw a close shave with Trident, a proposed NASA Discovery-class mission that would have flown by Neptune and its largest moon, Triton, in 2038. The agency chose to pass over that finalist mission in favor of two missions to Venus. , called DAVINCI+ and VERITAS.

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