Ebb and Flow were the twin space craft that mapped in the Moon’s gravitational field by flying near each other, and then as the gravity of the Moon tugged on them they could suss out how much gravity that was, exactly. The gravity map of the moon, actually two of them, at two different scales, is done, so the space craft were “de-orbited.”
To me, the first thing that is really interesting about this is the fact that they kept the space craft in very very low orbit for a long time. We earthlings tend to think of orbiting as something you have to do at high altitude, because we always send our satellites up high. But it is the atmosphere that requires that. With no atmosphere, an object can orbit a planet at very low altitude. Imagine that for a moment. Imagine that we form colonies on the moon and live there; there might well be regularly orbiting objects that would require that moon trucks stop for a moment at an intersection to allow them to pass. I’m not sure why such things would exist, but they could.
The mission scientists and engineers apparently had a great time flying ebb and flow down into low areas, pulling the two washing machine size science robots up just in time to miss hitting a ridge or crter wall or whatever, over the last several weeks. Getting in close to map gravity, I assume.
In the end, though, NASA was faced with needing to meet two objectives: 1) They can’t leave stuff in orbit because that is messy. So they needed to “deorbit” the space robots; and 2) They did not want the craft to have any fuel on board at the moment of … deorbiting. This is complicated because even though they have a very good idea of how much fuel is on board at any moment, there is some error in that measurement, and burning off the fuel for, say, 123 seconds vs. 126 seconds could make a huge difference in the final outcome.
If the space craft were far from the moon, you could just do that… the final speed of the space craft would not be too much of an issue. But since Ebb and Flow were at cropduster altitude (in space ship terms) a burn that would “point” the craft to the moon’s flat surface would be very inaccurate. So, what they did instead was to drive Ebb and Flow into the side of a mountain. This way, the burn could be more or less time and that would cause a change in speed, but the craft would still hit the mountain. And, this is what NASA did this afternoon.
Right after the event, NASA announced that the people who are in charge of naming things approved the mission staff’s request that the location of the crash-down be named after Sally Ride.
I remember finding out about the Tethys Sea and being really excited. I was just beginning my studies of Old World prehistory, Africa, and Human Evolution. What I learned about was the remnant sea separating Africa and Eurasia called Tethys, though it is much more than that (see below). Imagine a Eurasia with no Alps, no Caucasus, and no Arabian Peninsula. Much of southern Europe and huge swaths of North Africa are underwater, and Africa is so far away from Eurasia that all the classic seas of the region don’t exist simply because they are part of the ocean. If you were in the western Mediterranean, you would be able to travel across what is now the Black Sea to the Caspian Sea or the Persian Gulf and into the Indian Ocean, where you would not find India any where near it is today. That was all the Tethys. It allowed the world’s oceans to communicate not too far from the equator across the old world, instead of having the Indian and Atlantic oceans separated by Africa. Virtually everything about the modern climate system depends on tropical or subtropical closure of the major oceans. The fact that the Indian Ocean is on the equator and cut off from the North Atlantic determines and explains almost everything about Northern Hemisphere weather. The rest is explained by the Isthmus of Panama. Had Africa (and India) not moved north to close this sea and create the modern puddles known as the Caspian, Black and Aral seas, and the Persian Gulf, etc. there might well be no Atlantic Hurricanes, England would be rather cold, Canada might look much more like Greenland all year round, and if we add India moving north into Asia into the mix, and the formation of the great mountain ranges of Europe and Central Asia, we also get the present configuration of grasslands in Africa, and in fact, the evolution of grass itself. Prior to the closure of the Tethys, there was an oceanic habitat in Northern Africa and what is now Pakistan and Afghanistan in which evolved hippos, manatees, whales, and elephants. Probably. The sea was enormously influential and it’s demise equally so.
You know the story of Renaissance era scholars noticing sea shells made of lime stone high in the alps. Go look at the alps. Well, the geology there is pretty complicate, but the short version is that many of the fossil bearing (and other) sediments that the alps are made of were party of the western extent of the Tethys, during times when the Atlantic Ocean didn’t happen to exist, so if you were in a boat in that part of the Tethys you would not only be near Geneva (which didn’t exist yet) but also near Libya, Spain and Labrador. When the Tethys was finally pinched out the Alps, Caucuses, and other mountain ranges in the region were pushed up and those sediments exposed.
I’ve had close friends and colleagues who worked on a number of paleontological finds, and in some cases, I worked on them as well, that owe their existence to these dynamic changes. The hominoids of Pashalar were buried in sediments caused by landslides caused by uplift as Turkey became a place; The Siwalics, where all those amazing Asian pre-orang fossils were found, were once lowlands just risen from the sea, and later became the mountains of Pakistan. We will not speak of the Sahavi expedition, other than to say what is now among the driest deserts was once a sea in which it is possible, but highly unlikely, that early human ancestors rode on the back of dolphins swimming among hungry sharks. Well, the dolphins were swimming around among the sharks, anyway.
My own musings about this one thing … the sea that separated Africa from Eurasia, then went away as lands rose up and mountains formed, only addressed the latest period of the Tethys Ocean’s life. Like we have, mainly, the Atlantic and the Pacific today, in the very ver old days, even as life was just beginning to get complicated (and I don’t mean as in too many errands to run before Christmas, so much as I mean having more than one cell and organelles and stuff) it was the Tethys Ocean and the Panthalassic Ocean, the former to the east of, the latter to the west of, Pangea and the various daughter continents of Pangea as they formed over hundreds of millions of years.
It was in the Tethys that the Black Shales formed, during several (but many a few during a certain time period) in which a very large percentage of our oil was to be found, in many cases raised to dry land were it was easy (too easy, as it turns out) to get at. So, the Tethys sea gave us whales, and we used those for a while, but it also gave us Arabian Oil (and lots and lots of other oil around the world) which we are just now running out of.
So, given all this you can imagine how excited I was to see a book written just about the Tethys sea by an expert on it, who helped a great deal in developing our knowledge of it. Vanished Ocean: How Tethys Reshaped the World by Dorrik Stow is the story of the Tethys, told from the very beginning which is about a third of the way back to the very beginning of time itself, it’s fascinating disappearance. Stow is professor of Geoscience at Heriot Watt University, Edinburgh, and has a long history of research in oil geology and interpretation of deep sea cores. He was on some of the key deep sea coring projects that led not only to our understanding of the Tethys, but also, climate change.
To me, one of the most unsatisfying things one can do is to go to a place with interesting geology, stop in at the visitors center with the cute little museum, and see the same exact thing every time: “This region was once covered by a vast inland sea, bla bla bla” because those interpretive exhibits NEVER tell the most interesting aspects of the story. Like, the nearest shore off in that direction, even though you are currently in Michigan, was Norway and you could see if from here. Or, the rock formed by the reblown sand left behind when the sea receded is the same rock that outcrops at the other national park you visited five years ago and a thousand miles away. Or the wavy lines in this rock are from actual waves at the top of the water that were influenced by a wind that blew down from a mountain ridge that is now a low spot on a different continent, and when that was happening the only life on earth was … well there wasn’t any! (That sort of thing.) Vanished Ocean: How Tethys Reshaped the World actually undoes that frustration by placing a huge amount of what you will ever encounter in your life as a person interested in the Earth and its History in a single unified processual context. Not all, but a lot of it.
Let me start with this. People talking about Sandy Hook need to stop saying that “20 children between the ages of 5 and 10 were killed.” That is technically true but misses an enormously important point and indicates that you really haven’t thought this through. All of the children who were killed were born between September 2005 and December 2006. They were all in the first grade, all in the same school year, and most of them in the same exact class. Sandy hook had about 100 students in that year. Now, the class is 20% smaller.
This means that every year for the next few years there will be a special, demographic, reminder of the killings. This will be the year with one fewer teacher and slightly more crowded classrooms, or the same number of teachers with smaller than typical classes, compared to the year ahead or behind. This will be the year when the number of busses needed for a field trip will sometiems be less than needed for the year before or the year after, as time marches on. In this particular school district, students consolidate into a middle school in the fifth grade, so the demographic shift will be less noticeable. Instead of 20% of the students missing, it will be 5%. But, that is not a small number when counting students, teachers, busses, desks, etc. It will be subtle, but the 7th grade history teacher will wait an extra year to order new textbooks. You see, one of the reasons to order a new volume, besides staying current, is attrition on the numbers of available books. When this class arrives that won’t be an issue for one more year. And so on. Many little things like this will happen, every week, to teachers, students, administrators. The memory, and thus the horror, of the Sandy Hook killings will be manifest in the details and will keep sneaking up on these people when they least expect it.
This is nothing, of course, compared to the horrors of the deaths and the circumstances surrounding them. But there will be times when a teacher will remember her fellow educator slain on that day while grading assignments and feeling the difference in numbers, or a student will notice that her section of the 4th grade concert assembly is smaller because her four best friends were slain while she hid in a cabinet, hearing her teacher trick the gunman into leaving the classroom just before being pumped with bullets. Will she remember the sound of her body falling to the floor or was it masked by the repeated gunfire or did she hear both sounds from her hiding place? You and I don’t know, but she’ll remember. If they make cute little year books for Elementary School graduation, this class will use less space, and it will take less time at the ceremony to hand out the scrolls. This will dawn on someone in the audience who will then be reminded of the horror, and if you are there, you’ll hear the sobbing.
Anyway, stop saying “20 children between the ages of 5 and 10” because that ignores the very important fact that these children were all the same exact age, as ages go.
Now, on to this point: Stop telling me that your guns are important. I don’t care about your guns. I have hobbies too, that don’t happen to involve guns and I don’t ask you to adjust your politics, to take risks of life and limb, to ignore the horrors of daily gunplay among testosterone poisoned men taking lives every few hours somewhere in this country, of the thousands of youth suicides every year facilitated by easy access to unsecured deadly firearms or the occasional horrific massacre. Do don’t do that to me. Don’t make me respect your stupid hobby which has, as a side effect, the horror that happened last week and will happen again in a few months, because these things happen every few months, in case you have not noticed because you are too busy playing with your precious little guns.
And then this. Don’t give me your made up, out of date, or irrelevant statistics. There have been enough studies. Not all fears (about guns) are real, but most of the accolades given to gun ownership are pipe dreams, or really, gunplay fantasies. When a conceal carry law was passed in Minnesota, anti-gun people feared more shootings, pro-gun people said we’d all be safer because when trouble happened, good guys would draw guns and stop it. Guess what. Neither happened. We had a major massacre here, in fact, just recently, a workplace shooting. No good guys drew their guns. So even if the number of shootings did not go up, the “good side” of allowing people to walk around slinging guns like they lived in the wild west did not happen either. But otherwise, the statistics generally show that more guns equals more bad things that happen with guns. If good things happen because of these guns, they are very small in number, very infrequent, occur at a very low rate, if at all.
To depict these relationships I’ve drawn two graphs. I don’t need to base them on data, because even though you will say “You are not a real skeptic if you make a graph with no data” (I dare you, say it in the comments), these two graphs summarize all that we know to be pretty much true. Here they are:
Then this: The problem is the Second Amendment. With or without the Second Amendment, we could have sensible gun laws.Gun ownership could be legal, but guns could be better secured an less often used. But with the Second Amendment, the pro-gun lobby takes the most extreme stance possible because they argue that any limitations on gun use or ownership will lead to abrogation of all gun rights. I know lots and lots of gun owners who are happy with increased restrictions or increased security, but the NRA bought-and-paid-for elected officials and gun lobbyists don’t represent those reasonable people at all. They refuse to compromise. One of the false statistic you might have wanted to cite above before I told you to shut up is this: There have been lots of gun restrictions passed and they did not good. That is not true in two ways. First, increased restriction leads to fewer deaths, compared across states or across countries. Second, there have not been very restrictive gun laws passed, for the most part. I’ve seen gun nuts cite the assault weapons ban as having done nothing, without noting that it exists for a few years then expired.
Here’s the the thing. If gun ownership is OK, then lets make it ok, using laws. If gun owners really think that what they are doing is OK, then they should be able to do it without hiding behind an amendment that has nothing to do with Boys and their Toys or with Hunting, or even with addressing issues of crime, threats of rape, home invasion, etc. The Second Amendment does not limit restriction on guns so you can defend your home from criminals or go hunting. It is to defend your home from the British. If what you are doing with your guns is really OK, then why do you want to hide behind an atavistic centuries old out of date no longer relevant amendment?
So here’s what we do, OK? First, we get rid of the Second Amendment. Then, we talk. In the mean time, keep your fucking guns away from me and stop complaining. Society has reached a tipping point. We are tired of your bullying, your whining, your childish insistence that you are doing something important with your toys, because for the most part, you are not.