International Space Agencies – Missions and Discoveries

Voyager 2 Spacecraft

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Voyager Mission, Heliosphere

Mains level : Particulars of the space mission


  • NASA’s Voyager 2 has become the second human-made object in history to reach the edge of our solar system.
  • The spacecraft exited the protective bubble of particles and magnetic fields created by the Sun.

Voyager 2

  • Voyager 2 was launched in 1977, 16 days before Voyager 1, and both have travelled well beyond their original destinations.
  • The spacecraft were built to last five years and conduct close-up studies of Jupiter and Saturn.
  • As the spacecraft flew across the solar system, remote-control reprogramming was used to endow the Voyagers with greater capabilities than they possessed when they left Earth.
  • It carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.
  • It is slightly more than 18 billion kilometres from Earth. Its twin, Voyager 1, crossed this boundary in 2012.
  • Their five-year lifespans have stretched to 41 years, making Voyager 2 NASA’s longest running mission.

What is Heliosphere?

  • The heliosphere is the vast, bubble-like region of space which surrounds and is created by the Sun.
  • In plasma physics terms, this is the cavity formed by the Sun in the surrounding interstellar medium.
  • The “bubble” of the heliosphere is continuously “inflated” by plasma originating from the Sun, known as the solar wind.
  • Outside the heliosphere, this solar plasma gives way to the interstellar plasma permeating our galaxy.
  • The boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium.

Still in the solar system

  • While the probes have left the heliosphere, Voyager 1 and Voyager 2 have not yet left the solar system, and won’t be leaving any time soon.
  • Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information —moving at the speed of light — takes about 16.5 hours to travel from the spacecraft to Earth.
  • By comparison, light travelling from the Sun takes about eight minutes to reach Earth.

Future missions of NASA

  • 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.
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