Voyager 1 and 2 have been gone for a LONG time now (decades) and presumably we can produce bigger, faster and better probes these days that could tell us a lot more about the heliosphere. I've not found any articles or pieces about any planned missions to exit the solar system in the future.

So was that it? Voyager 1 and 2 were our only efforts? Or are there other missions planned to exit the system? I'm not talking about Kepler which to its credit is locating extra-solar planets and systems, but more about craft which will actually exit the solar system as we know it.


You are forgetting Pioneer 10, Pioneer 11, and New Horizons. Pioneers 10 and 11 respectively operated for 28 years and 16 years after completing their primary missions. New Horizons, which has yet to perform its primary mission (Pluto flyby in July 2015) or secondary mission (TBD flyby of a Kuiper belt object) will reach the heliopause in about 2047.

No future extra-solar missions are currently planned by NASA or by ESA. There were some initial investigations toward a New Horizons follow-on, but nothing substantive came of those investigations. It was deemed better to wait for New Horizons to successfully complete its primary mission before even starting to consider a follow-on.

There's too little science return compared to the expense to justify making escaping the solar system the primary mission of a spacecraft. The extra-solar missions of those five escaping satellites were/are tertiary missions. The Voyager missions would have been deemed a complete success had both those spacecraft failed immediately after completing their grand tours.

  • $\begingroup$ (facepalm) forgot about 10 and 11. Good point about NH - at least it'll give us some good stuff. I'd just love some more data or sound or anything from out there (sighs) :) $\endgroup$ – Mark Mayo Jan 5 '15 at 13:21
  • $\begingroup$ Note: This answer was written in December 2014, well before New Horizon's July 2015 flyby of Pluto. Please do not edit this answer to reflect the fact that the flyby has now occurred. $\endgroup$ – David Hammen Jul 28 '15 at 8:11

As David Hammen stated in his previous answer, neither NASA, ESA or any other space program has any extra-solar mission in the works. However, there are many studies of interstellar and interstellar precursor missions, some of them ongoing.

Perhaps the best known and most advanced interstellar probe is Project Icarus (wiki). This is a modern redesign of an earlier project from the 70s known as Project Daedelus. Icarus Interstellar is a collaborative project of the Tau Zero Foundation and the British Interplanetary Society, the latter of which came up with Daedelus. Both ship designs rely on nuclear propulsion to attain an appreciable fraction of the speed of light in order to reach a close star system within a century.

NASA produced a study on what they called the Innovative Interstellar Explorer:

This study focused on the elusive quest to reach and measure the interstellar medium, the region outside the influence of the nearest star, the Sun. It proposes to use a radioisotope thermal generator with ion thrusters.(1) The project is a study of a proposed interstellar precursor mission that would probe the nearby interstellar medium and measure the properties of magnetic fields and cosmic rays and their effects on a craft leaving the Solar System.(2)

Using an ion drive with xenon propellant, it could attain 1000 AU within 100 years of launch (updates here and here, slide show here).

Another interstellar precursor probe is Project FOCAL, a proposal by Italian physicist Claudio Maccone. The idea is to send a probe out to 550 AU and beyond in order to use the Sun as a gravitational lens.

I would be remiss if I did not mention the 100 Year Starship Project, headed by American physician and former NASA astronaut Mae Jemison. This is a DARPA sponsored project to come up with a business plan for research on interstellar travel over the next hundred years.


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