NASA’s Voyager 2 spacecraft enters into interstellar space – Science News
After 41 years on the road, NASA’s Voyager 2 spacecraft has finally entered interstellar space, but it still has a long way to go before it leaves the solar system.
The spacecraft moved beyond the protective bubble of particles and magnetic fields created by the Sun known as the heliosphere, NASA has confirmed.
Its twin, Voyager 1, crossed a different part of this boundary in 2012.
“We’re all happy and relieved that the Voyager probes have both operated long enough to make it past this milestone,” Suzanne Dodd, the Voyager project manager from NASA’s Jet Propulsion Laboratory said.
“This is what we’ve all been waiting for. Now we’re looking forward to what we’ll be able to learn from having both probes [in interstellar space],” Ms Dodd said in a statement.
Both spacecraft are still in regular contact with NASA’s Deep Space Network (DSN) ground stations, including Australia.
Unlike Voyager 1, Voyager 2 has instruments on board that measure changes in the speed and direction of high-energy plasma particles as the wind from our Sun meets the high-energy particles streaming in from the rest of the galaxy.
The NASA scientists detected a drop in the flow of the solar wind created by our Sun around November 5.
The energy streaming from our own Sun is literally like a wave around the solar system, Glen Nagle of the Canberra Deep Space Communication Complex said.
“It’s the same way as a ship cutting through water creates a bow shock wave around it.
“The Voyager spacecraft are now ahead of that wave in the clear air of interstellar space.
“Voyager 2 seems to have entered that region about 18 billion kilometres from the Sun.”
The journey to the edge
Voyager 2 was launched on August 20 1977 — 16 days before its twin Voyager 1 — making it the oldest space mission.
“Its mission was to go and visit the giant planets of the solar system Jupiter, Saturn and of course eventually Uranus and Neptune,” Mr Nagle said.
It is the only spacecraft to have flown by Uranus, in 1986, and Neptune, in 1989.
Since then it has continued its journey though the solar system towards interstellar space.
“Nobody really expected the spacecraft to last this long, to be able to continue out on their journey, to travel through the heliosheath boundary, out across the heliopause into interstellar space,” Mr Nagle said.
But it still has a long way to travel until it reaches the edge of the solar system, which is defined by a halo of objects such as comets known as the Oort Cloud.
The Oort Cloud starts around 150 billion kilometres from the Sun and extends out to about 30 trillion kilometres.
“The influence of our Sun extends much further out than where the Voyager spacecraft are. Out to the gravitational influence of the Sun,” Mr Nagle explained.
But, at its current flight speed covering 1.4 million kilometres a day, it won’t even reach the inner edge of the Oort Cloud for another 300 years and maybe not exit it for another 30,000 years.
Interstellar space to Australia…
Voyager 2’s journey will continue to be monitored by the Canberra tracking stations and the Parkes Radio Telescope.
Unlike Voyager 1, Voyager 2 can only be seen from the southern hemisphere, astronomer Fred Watson said.
“Its trajectory took it south of the plane of the solar system, so you need southern hemisphere facilities in order to pick up [its signals],” Professor Watson told The World Today.
Mr Nagle said the tracking stations were talking to Voyager 2 for about 15 hours a day.
“The spacecraft no longer has a working recorder on board so it is continuously streaming back that information,” Mr Nagle said.
Mr Nagle said the spacecraft had enough power to run science instruments until 2025.
Although the science mission will be over by that time, the spacecraft will still send data back about its health and position for many years.
“We may have contact with Voyager 2 right through until the early 2030s,” Mr Nagle said.
“That’s an incredible journey for this amazing little … spacecraft.”