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Posted by: jasedm Nov 7 2007, 03:27 PM

As of today, we have photographs and maps of many of the surfaces of the larger solid bodies of the solar system (including two shrouded in dense atmospheres) I was wondering what are the largest expanses of unknown terrain (by this I mean not imaged at a resolution better than 15km or so) remaining in the solar system today, and came up with the following.

The figures are inevitably approximate, are in square kilometres and I'm ignoring our own planet's ocean-floors.

Mercury (the 30-ish% not photographed by Mariner or radar-imaged from Arecibo) - 22,500,000
Pluto/Charon - 21,310,000
Titan (the remaining 25-ish% not yet imaged from Cassini) - 20,825,000
Eris - (dwarf planet/TNO) - 18,100,000
Neptune system (~half of Triton plus Proteus and Nereid) - 13,600,000
Uranus system (Over half of each of the moons Miranda through Oberon) - 13,400,000
Jupiter system (pole areas of the galileans) 11,600,000
2005fy9 - (TNO) - 10,200,000
2003el61 - (TNO) - 6,970,000
Sedna - (TNO) - 6,970,000
Quaoar - (TNO) - 4,990,000
Ceres/Vesta - 3,722,000 (I've lumped these together for obvious reasons)

For comparison, these add up to just over the dry-land surface of Earth (which is 148,940,000 square km)

Incidentally, pre-Cassini, Titan alone comes out at 83,300,000 square km

Interesting to note that the top three will have been imaged at good or very good resolution in the next ten to fifteen years.
We may get a mission each to Uranus and Neptune in my lifetime, but I don't expect my children will get to see what Eris looks like up-close in theirs.

Posted by: djellison Nov 7 2007, 04:27 PM

And the bottom ones as well.

Doug

Posted by: David Nov 7 2007, 08:16 PM

It seems likely that there are a good many large bodies in or beyond the Kuiper belt that we not only haven't imaged and won't image any time soon, but which we don't even know exist yet.

Just 50 years ago, the only celestial body which had been mapped in any detail was the 60% or so of the Moon which is visible from Earth's surface; Venus was a total unknown, Mars a few suggestive but hard-to-interpret blotches, Mercury an even more remote set of specks, all other rocky or icy bodies mere points in the telescope.

Posted by: jasedm Nov 10 2021, 08:08 PM

Apologies for resurrecting an archaic thread, but I felt it was apposite to update this one as a huge amount has been achieved in the intervening 14 years.

/Nerd alert/

To recap, these are areas of various bodies not yet imaged at better than 15km resolution in our solar system. The figures are inevitably approximate, are in square kilometres and I'm ignoring our own planet's ocean-floors.

Mercury - Messenger achieved 100% mapping in 2013
Pluto/Charon - I'm guessing perhaps half of Pluto/Charon was imaged at 15km resolution or better, leaving 10,600,000
Titan - Perhaps 10% not imaged by Cassini-Huygens at that resolution? - 8,300,000
Eris - (dwarf planet/TNO) - 18,100,000
Neptune system (~half of Triton plus Proteus and Nereid) - 13,600,000
Uranus system (Over half of each of the moons Miranda through Oberon) - 13,400,000
Jupiter system (pole areas of the Galileans) 11,600,000
2005fy9 - Now named Makemake - 10,200,000
2003el61 - Now name Haumea - 6,970,000
Sedna - 6,970,000
Quaoar - 4,990,000

Ignoring everything outside of Pluto's orbit, these add up to 57,500,000 - roughly equivalent to the area of Asia and Europe.

Two missions to the Jupiter system (Europa Clipper and Juice) should improve on Galilean coverage in the next 15 years and we've had a few bonuses as well (several comets, and parts of the moons of Pluto)

It would be amazing to have Cassini-type missions to the Uranus and Neptune systems (Radar-equipped at Uranus because of the axial tilt) and this would give us coverage of half the remaining total.

Jase

Posted by: volcanopele Nov 10 2021, 08:22 PM

If the cut off is 15 km/pixel, the polar regions of Io should fare better after early 2024.

Posted by: stevesliva Nov 11 2021, 04:44 PM

Which is pretty cool!

On the other hand, the fractal nature of things for small bodies means you'll never see it all if you make the scale small enough.

Posted by: jasedm Nov 11 2021, 07:42 PM

True, and everything is fascinating. From the fluffball that is Methone, to the amazing landscapes on Churyumov-Gerasimenko, to Pluto/Charon (who envisaged they would be so dynamic prior to New Horizons?)

I think Psyche will be quite something to see up-close, and I'm really looking forward to Europa Clipper

Posted by: JRehling Nov 11 2021, 10:50 PM

FWIW, Pallas has about 800K km^2 of area, but the resolution for asteroids observed from Earth is already approaching, and will likely within the next decade exceed the offered threshold.

For many worlds (e.g., Pluto, Charon, and the satellites of Uranus and Neptune) the unobserved territory is going to be largely or entirely represented by the territory already observed. To some extent, lower resolution imagery can corroborate that likelihood. So in that respect, I'd say that Eris looms as plausibly the main repository of truly unknown terrain. The fact that Triton and Pluto turned out to be as different as they are bolsters the curiosity, I'd say, about how Eris evolved.

Of course, we never know what we don't know, and some small world or some highly anomalous tidbit of a world we've already seen in part may turn out to be startlingly unique. Maybe the 5th or 10th biggest KBO will turn out to be the most interesting one.