• Question: How far have we explored in our solar system?

    Asked by amy to Heather, Helen, Hugh, Jane, Julian on 11 Nov 2014.
    • Photo: Julian Onions

      Julian Onions answered on 11 Nov 2014:

      We have explored most of the inner solar system. Mars is perhaps the best explored planet, with several missions currently working on the planet. In some ways we know more about Mars than the Earth.
      The moon we’ve been to, and mapped pretty completely.
      Venus less so, although we have very good radar maps of Venus, the hostile conditions there make landers very difficult. They tend to be crushed, melted (500C) and assaulted by acid rain all at once.
      There is currently a probe mapping Mercury, and the Sun is kept under observation by a number of satellite and Earth based observatories.
      Jupiter and Saturn have both had missions to them, Saturn still has one Cassini.
      Uranus and Neptune are much less explored, they have only had flyby missions and those a long while ago. Technology has moved on a lot since then.
      After that there is less exploration, although there is a mission to Pluto currently, which will be arriving next year, but is going so fast it will only be able to snap a few pictures as it passes.

      So – we have done a pretty good job on most planets, but as scientists we always want to know more. So there are many more missions planned!

    • Photo: Jane MacArthur

      Jane MacArthur answered on 11 Nov 2014:

      In pure distance terms, the Voyager 1 spacecraft is currently about 12 billion miles from the Earth, 130 Astronomical Units (AU). One AU is defined as the distance from the Earth to the Sun, which is a convenient way to imagine the distance instead of numbers with lots of zeros! This is the furthest any spacecraft has explored and it is thought to have now left the region of our Sun’s influence and entered interstellar space.

      Most excitingly, the Rosetta mission (ESA) is currently exploring a comet, and hopes to land on it tomorrow! (Wed 12th Nov, 2014). The Philae lander will be released just after 9am and it will be a very tense 7 hours, confirmation of landing is hoped for around 4pm. If successful, you may see the first ever images taken on a comet between 5-6pm showing up on the news.

      Our only glimpses of Uranus and Neptune were from Voyager 2 in 1986 and 1989, and as Julian said our first close up information about Pluto will be provided by the New Horizons mission next year. The outer solar system needs much more exploration, in my view.

      Cassini has provided amazing images and data about Saturn, yet the more we learn, the more detailed and interesting our questions become. Its largest moon, Titan, is known to have a methane-cycle similar to our water cycle, while Enceladus (an ‘icy moon’) has icy water jets spraying out of its south pole. The Cassini mission will end in 2017 and although many exciting follow ups have been proposed (eg a boat on Titan!), none have so far been selected.

      The European Space Agency is launching Bepi Colombo to Mercury in 2016. Mercury has been a difficult planet to explore as spacecrafts have to withstand high temperatures being so much closer to the Sun.

      Given the millions of asteroids in the asteroid belt, this region is currently under-explored. We have two asteroid-sample-return missions being planned. The Japanese are launching Hayabusa 2 next month (after successfully returning samples with the original Hayabusa mission), and NASA plan to launch OSIRIS-REx in 2016.

    • Photo: Helen Johnson

      Helen Johnson answered on 12 Nov 2014:

      The Voyager spacecraft (1 and 2) were definitely among the most incredible achievements of the 70s/80s. There was a rare arrangement of the outer planets back then, that meant we could visit 4 of them all in one go! We got some fantastic photos and data from Jupiter, Saturn, Uranus and Neptune, and learned a huge amount. Voyager 1 is now officially out of our solar system, and has travelled further than any man-made object in history.

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