Gone Fishing on Ganymede

In the past, fishing was a skill used to provide food for the table. Whether or not ancient man enjoyed the process, they needed to be good at it – or at hunting – in order to thrive. Today, fishing on a personal level has become a pleasurable activity for some. They don’t need to do it to put fish on the dinner table, but they find the experience rewarding. Some go so far as to try for ‘a big fish’ out in the middle of the ocean.

What do you suppose will happen when humans find their way to other planets?

Water has been found on our moon, Mars, Ceres, even Pluto, as well as various other places. On Ganymede, a moon of Jupiter, salty water is hidden under a thick (about 95 miles) crust of ice. There is probably more water on Ganymede than all of the Earth’s surface water combined. Scientists believe that ocean is 60 miles deep, about 10 times the deepest part of any Earth ocean.

I can envision future tours being organized to take die-hard fishers to Ganymede to drill a big hole in the exterior ice to facilitate fishing. I doubt if they’ll dangle a 100-mile-long fishing line into that hole – think how long it would take to reel it back in! So maybe their spacesuit for leaving the space boat would also be a diving suit, and they would ‘hunt’ for ‘fish’ with a spear gun.

Hmm. There’s problems with that vision, according to some of what I read. The Ganymede’s ocean is not only covered with ice, it also rests on ice, pressurized into a crystalized form. On other moons, the ocean bed is rock, which apparently keeps the water warmer, and provides various minerals as it is eroded by the salty ocean. The theory is that those warmer, rock-bedded oceans are far more likely to produce some kind of ‘life.’

Still, we keep getting surprised, the more we look around our neighborhood, don’t we? And science fiction writers like to take the science we know now and extrapolate possibilities we don’t – yet - have any proof for.

So, how about this? There’s a lot of different salts, besides table salt, which could be helping Ganymede’s ocean remain liquid. Nobody definitively stated the only salt in Ganymede’s ocean was NaCl (table salt), so these other salts could provide minerals for building ‘life’. I’m not sure the temperature of the ocean is that big a deal, but the salty ocean of Ganymede reacts to the magnetic field of Jupiter, and I’m thinking that reaction might produce some heat, although probably not much.

Sounds good to me. So good, I anticipate someone will make some money someday, selling signs that say, “Gone Fishing on Ganymede.”

http://www.space.com/28807-jupiter-moon-ganymede-salty-ocean.html

http://earthsky.org/space/underground-ocean-on-jupiters-largest-moon

http://www.planetary.org/blogs/emily-lakdawalla/2015/03121716-ganymede-ocean.html

Oldest People in England

Anthropologists theorize that the human family tree began in Africa, and at some point, various versions of our ancestors spread into the Arabian peninsula, Europe, Asia, Australia… and eventually the Americas. Lucy and the skeletons of many other almost-humans have been found scattered across Africa. Besides the skeletons and various stone tools, scientists have also discovered footprints, most notably some that are 3.75 million years old in Tanzania, and others left 1.5 million years ago in Kenya.

Long ago, I read that footprints were not a common find in the world of paleontology and anthropology; the footprint had to be made in a type of soil soft enough to take an impression, but firm enough to retain it, then covered and filled in by something else that would not disturb the impression. After all, a footprint is not a body that can be fossilized; it’s an impression that needs to be retained without being squashed.

But lately, I wandered across an article concerning ancient footprints discovered in England. These are the oldest footprints discovered (so far) outside Africa.

In May of 2013 (reported in February of 2014), about 50 footprints were discovered in Happisburgh, in Norwich. Previous footprints found in England were only 7,500 years old, but the Happisburgh prints were 900,000 years old, made by members of the extinct homo antecessor branch. (You remember Aunty Cessor, don’t you? No? Perhaps she was a bit before your time.) The prints came to light on the beach through erosion, and unfortunately, they disappeared the same way. Scientists got them measured and photographed, but only lifted a mold from one before they were gone.

These prints were made by 5 individuals, both adult and children, walking across the wet silt of an ancient estuary. They are the oldest direct evidence of humanoids in all of Europe, let alone England. The next oldest evidence in Europe is a 780,000 year old skull fragment found in southern Spain. Before this discovery, England had some 700,000 year old stone tools to indicate a human presence.

How did people get across the Channel to trek to the west side of the island? At 1,000,000 years ago, there was no channel; England was connected by land to the mainland, and that could have been the case for another 100,000 years. Maybe a geologist could tell you when the channel became a water-way, but the Happisburgh footprints were made just as the ice age was beginning, so the water level was lower.

http://www.independent.co.uk/news/science/archaeology/news/the-million-year-old-family-human-footprints-found-in-britain-are-oldest-ever-seen-outside-of-africa-9114151.html

http://www.telegraph.co.uk/news/science/science-news/10623660/900000-year-old-footprints-of-earliest-northern-Europeans-discovered.html

http://www.bbc.com/news/science-environment-26025763