【历史性时刻:旅行者2号成为第二个进入星际空间的人造物体】

【历史性时刻:旅行者2号成为第二个进入星际空间的人造物体】昨日零点,NASA在美国地球物理学会会议上宣布,旅行者2号探测器已经穿越了日光层,进入星际空间,成为继旅行者1号后第二个进入星际空间的人造物体。目前旅行者2号自1977离开地球后已造访多颗行星,目前距离地球超过180亿公里,通讯正常,不过若要离开太阳系,可能还需上万年。

Historic moment NASA announces its Voyager 2 probe has become the second man-made object to enter interstellar space

  • NASA 's Voyager 2 probe has now exited the heliosphere, six years after its twin Voyager 1 did the same
  • The heliosphere is the protective bubble of particles and magnetic fields created by the sun
  • The twin probes have left the heliosphere, but have not yet left the solar system 
  • The historic news was revealed at meeting of American Geophysical Union in Washington 

History has been made today as NASA's Voyager 2 probe became the second man made object to venture out into interstellar space.

The announcement came six years after its twin spacecraft, Voyager 1, broke free from the protective bubble around the Sun - the heliopause.

This is the region where the hot solar wind meets the cold, dense space between stars, known as the interstellar medium.

Voyager 2 is now more than 11 billion miles (18 billion kilometres) from Earth, having passed this boundary on November 5.

The announcement came six years after its twin spacecraft, Voyager 1, broke the outer boundary of the heliopause, where the hot solar wind meets the cold, dense space between stars, known as the interstellar medium 

The announcement came six years after its twin spacecraft, Voyager 1, broke the outer boundary of the heliopause, where the hot solar wind meets the cold, dense space between stars, known as the interstellar medium

WHAT IS THE HELIOSPHERE?

The sun sends out a constant flow of solar material called the solar wind, which creates a bubble around the planets called the heliosphere.

The heliosphere acts as a shield that protects the planets from interstellar radiation.

Voyager 2 passed the outer edge of the heliosphere on Nov. 5.

This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium.

The news was revealed at a meeting of the American Geophysical Union (AGU) in Washington.

Comparing data from different instruments aboard the spacecraft, mission scientists believe the probe crossed the outer edge of the heliosphere on Wednesday last week.

'This time is even better for us,' said Nicky Fox, director of the heliophysics division at NASA, noting that one instrument, called the Plasma Science Experiment (PLS), is still functioning on Voyager 2.

'To have the Voyagers sending back information about the edge of the Sun's influence gives us an unprecedented glimpse of truly uncharted territory.'

The same instrument on Voyager 1 - which crossed this boundary in 2012 - stopped working in 1980.

However, Voyager 2 still carries the instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.

The two spacecraft, which look like a combination of a satellite dish and an old television set with rabbit ear antennas, were launched in 1977 on a mission to explore planets in our solar system.

The twin probes have left the heliosphere, but have not yet left the solar system, 'and won't be leaving anytime soon,' NASA said.

The boundary of the solar system is considered to be beyond the outer edge of the Oort Cloud.

This is a collection of small objects that are still under the influence of the sun's gravity.

The width of the Oort Cloud is not known precisely, but it is estimated to begin at about 1,000 astronomical units (AU) from the sun and to extend to about 100,000 AU.

One AU is the distance from the sun to Earth.

It will take about 300 years for Voyager 2 to reach the inner edge of the Oort Cloud and possibly 30,000 years to fly beyond it.

'We're looking forward to what we'll be able to learn from having both probes outside the heliopause,' said Suzanne Dodd, Voyager project manager at NASA's Jet Propulsion Laboratory in Pasadena, California.

Voyager 2 is officially NASA's longest-running mission.

Voyager 1 and 2 both carry a Golden Record of Earth with 115 pictures of life on our planet and messages in 59 languages that aim to serve as evidence of our civilisation.

The 12-inch gold-plated copper disk contains a variety of natural sounds, such as waves, wind, thunder, birds, whales and other animals.

It also has a message from Jimmy Carter who was the US president when the spacecraft launched.

'This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings', he said.

'We are attempting to survive our time so we may live into yours.'

The two spacecraft were designed to last five years and study Jupiter and Saturn.

'Both spacecraft are very healthy, if you consider them senior citizens,' said Suzanne Dodd, Director for the Interplanetary Network Directorate, as the science results were unveiled at the American Geophysical Union annual meeting in the US capital.

Until recently, the space surrounding Voyager 2 was filled predominantly with plasma flowing out from our sun.

This outflow, called the solar wind, creates a bubble – the heliosphere – that envelopes the planets in our solar system.

The PLS uses the electrical current of the plasma to detect the speed, density, temperature, pressure and flux of the solar wind.

The PLS aboard Voyager 2 observed a steep decline in the speed of the solar wind particles on 5 November.

This is consistent with the conclusion that Voyager 2 has crossed the heliopause.

Voyager's team members are eager to continue to study the data from these other on-board instruments to get a clearer picture of the environment through which Voyager 2 is travelling.

A key concern is power, and NASA has to keep shutting down instruments to reserve power. But they may have five to 10 years left of life, she said.

NASA also is preparing an additional mission – the upcoming Interstellar Mapping and Acceleration Probe (IMAP), due to launch in 2024 – to capitalise on the Voyagers' observations.

'Voyager has a very special place for us in our heliophysics fleet,' said Dr Fox.

'Our studies start at the Sun and extend out to everything the solar wind touches.

'To have the Voyagers sending back information about the edge of the sun's influence gives us an unprecedented glimpse of truly uncharted territory.'

The Voyager probes are powered using heat from the decay of radioactive material, contained in a device called a radioisotope thermal generator (RTG).

Members of NASA's Voyager team will discuss the findings at a news conference at 11 a.m. EST (8 a.m. PST) today at the meeting of the American Geophysical Union (AGU) in Washington.

The news conference will stream live on the agency's website.

原文链接:https://www.dailymail.co.uk/sciencetech/article-6479655/Nasas-Voyager-2-second-man-object-leave-solar-system.html


Comments are closed.



无觅相关文章插件