Voyager 2 passes by Neptune, 35 years in the past
Thirty-five years in the past, on August 25, 1989, NASA’s Voyager 2 spacecraft made an in depth flyby of Neptune. It gave humanity its 1st close-up of our solar system’s eighth planet. It additionally marked the top of the Voyager mission’s Grand Tour of the solar system’s 4 giant planets, Jupiter, Saturn, Uranus and Neptune. No different spacecraft has visited Neptune since.
Ed Stone, a professor of physics at Caltech and Voyager’s undertaking scientist since 1975, mentioned:
The Voyager planetary program actually was a chance to indicate the general public what science is all about. Each day we discovered one thing new.
Wrapped in teal and cobalt-colored bands of clouds, the planet that Voyager 2 revealed appeared like a blue-hued sibling to Jupiter and Saturn. The blue on Neptune signifies the presence of methane. An enormous, slate-colored storm was dubbed the Great Dark Spot, much like Jupiter’s Nice Purple Spot. Plus, Voyager 2 found six new moons and 4 rings.
Voyager 2 additionally visited Triton
In the course of the encounter, the engineering group fastidiously modified the probe’s path and velocity in order that it might do an in depth flyby of the planet’s largest moon, Triton. The flyby confirmed proof of geologically younger surfaces and energetic geysers spewing materials skyward. This indicated that Triton was not merely a strong ball of ice although it had the bottom floor temperature of any pure physique noticed by Voyager: -391 levels Fahrenheit (-235 levels Celsius).
Voyager 2 onward to interstellar space
The conclusion of the Neptune flyby marked the start of the Voyager Interstellar Mission. Forty-seven years after launch, Voyager 2 and its twin, Voyager 1 (which had additionally flown by Jupiter and Saturn), continue to send back dispatches from the outer reaches of our solar system. On the time of the Neptune encounter, Voyager 2 was about 2.9 billion miles (4.7 billion km) from Earth. In the present day it’s 12.7 billion miles (20 billion km) from us. The faster-moving Voyager 1 is 15.2 billion miles (24 billion km) from Earth.
Getting there
By the point Voyager 2 reached Neptune, the Voyager mission group had accomplished 5 planetary encounters. However the huge blue planet nonetheless posed distinctive challenges.
Neptune is about 30 instances farther from the sun than Earth. So, the icy big receives solely about 0.001 instances the quantity of daylight that Earth does. In such low mild, Voyager 2’s digicam required longer exposures to get high quality photos. However the spacecraft would attain a most velocity of about 60,000 mph (90,000 kph) relative to Earth. So, a protracted publicity time would make the picture blurry. (Think about attempting to take an image of a roadside signal from the window of a dashing automotive.)
So the group programmed Voyager 2’s thrusters to fireplace gently through the shut strategy, thus rotating the spacecraft to maintain the digicam targeted on its goal with out interrupting the spacecraft’s general velocity and path.
Receiving the radio indicators from Neptune
The probe’s distance meant by the point radio indicators from Voyager 2 reached Earth, they have been weaker than different flybys. However the spacecraft had the benefit of time. The Voyagers talk with Earth by way of the Deep Space Network, or DSN, which makes use of a number of radio antennas. They’re in Madrid, Spain; Canberra, Australia; and Goldstone, California. Throughout Voyager 2’s Uranus encounter in 1986, the three largest DSN antennas have been 64 meters (210 toes) extensive. To help with the Neptune encounter, the DSN expanded the dishes to 70 meters (230 toes). Additionally they included close by non-DSN antennas to gather information, together with one other 64-meter (210 toes) dish in Parkes, Australia. And a number of 25-meter (82 toes) antennas on the Very Giant Array in New Mexico.
The hassle ensured that engineers might hear Voyager loud and clear. It additionally elevated how a lot information might attain Earth in a given interval, thus enabling the spacecraft to ship again extra photos from the flyby.
Being there
Within the week main as much as that August 1989 shut encounter, the ambiance was electrical at NASA’s Jet Propulsion Laboratory in Pasadena, California, which manages the Voyager mission. As photos taken by Voyager 2 throughout its Neptune strategy made the four-hour journey to Earth, Voyager group members would crowd round pc screens across the Lab to see. Stone mentioned:
One of many issues that made the Voyager planetary encounters totally different from missions at the moment is that there was no web that might have allowed the entire group and the entire world to see the images on the identical time. The pictures have been accessible in actual time at a restricted variety of areas.
However the group was dedicated to giving the general public updates as shortly as attainable. So from August 21 to August 29, they might share their discoveries with the world throughout day by day press conferences. On August 24, a program known as Voyager All Evening broadcast common updates from the probe’s closest encounter with the planet, which passed off at 4 a.m. GMT (9 p.m. in California on August 24).
The subsequent morning, Vice President Dan Quayle visited the lab to commend the Voyager group. That evening, Chuck Berry, whose track Johnny B. Goode was included on the Golden File that flew with each Voyagers, performed at JPL’s celebration of the feat.
Voyagers have been profitable and proceed at the moment
After all, the Voyagers’ achievements prolong far past that historic week over three a long time in the past. Each probes have now entered interstellar space after exiting the heliosphere, the protecting bubble across the planets created by a high-speed circulate of particles and magnetic fields spewed outward by our sun.
They’re reporting again to Earth on the “climate” and circumstances from this area stuffed with the particles from stars that exploded elsewhere in our galaxy. They’ve taken humanity’s first tenuous step into the cosmic ocean the place no different working probes have flown.
Voyager information additionally complement different missions, together with NASA’s Interstellar Boundary Explorer (IBEX), which is remotely sensing that boundary the place particles from our sun collide with materials from the remainder of the galaxy. And NASA is getting ready the Interstellar Mapping and Acceleration Probe (IMAP), because of launch in 2025, to capitalize on Voyager observations.
The Voyagers ship their findings again to DSN antennas with 13-watt transmitters, about sufficient energy to run a fridge mild bulb. Stone mentioned:
Each day they journey someplace that human probes have by no means been earlier than. Years after launch, they usually’re nonetheless exploring.
More information about the Voyager mission
More images of Neptune taken by Voyager 2
Backside line: It has been 35 years since Voyager 2 visited Neptune as a part of the Voyagers’ Grand Tour of our solar system’s 4 big planets. As of at the moment, no different earthly spacecraft has returned to Neptune.
Where is Voyager 2 going? And when will it get there?
Read more: Why are the Voyager spacecraft getting closer to Earth?
