Monday, November 17, 2014

Securing Our Future Water Needs

Last night, CBS 60 minutes had a story about the loss of water the Western US is experiencing due to a drought we've experienced over the last 9 years or thereabouts. The story centered around a study that came about in part thanks to the NASA GRACE Satellite Mission. GRACE stands for Gravity Recovery And Climate Experiment, and has used the Earth's local gravitational pull on the satellite to determine such things as the loss of water mass in the ground below the satellite. The researchers have determined that 75% of the water lost over the last 9 years in the Colorado River Basin has been from underground water sources. In other words, the aquifers are being pumped dry to compensate for the lack of surface water due to the drought, and there is some concern that we may run out of underground water and thus water in general to grow crops out in the West. If you were thinking that losing the west's crops would be no big deal, you would be very wrong. California alone produces a surprising amount of the US's fruits and vegetables. The list is extensive.

There is some research which suggests that the California drought is linked to climate change. In particular, due to the formation of a permanent high-pressure system next to California which is diverting rain away from the state. So this drought condition may be with us for the long term. If so, we need to start coming up with alternative fresh water sources to keep ourselves afloat.

I want to suggest areas of research that may help with the water supply problem. They may not solve the problem, so much as alleviate the symptoms. My interest is in desalinization of sea-water using minimal energy techniques, and with minimal cost. It isn't entirely obvious that both of these techniques would be low-energy or low-cost, but the thought experiment is at least worthwhile. Here they are, at any rate:

Dig a Well in the middle of the Ocean

This idea may have no validity at all. It's so simple, I have no idea why it hasn't already been tried. The most likely reason is because it wouldn't work, but here goes anyway... Reverse Osmosis (RO) works by driving Sea Water through a membrane that separates the salt in the sea-water from the fresh water. If you put Sea Water at 400 PSI on one side of the membrane, fresh water will leak out the other side. Generally sea water is pumped across one side of the membrane, becoming more saline as it passes along, and fresh water is yielded on the other side. You need at least 391 PSI of water pressure to overcome the "osmotic pressure" of the salt in sea water. Anything less than that won't yield fresh water. With these bits of data in mind, here's the first solution: A submersible well pump is placed in the middle of a membrane wrapped container that is dropped into 1000 foot deep water off the California coast (we have water that deep, close to the shore all along the Monterey Bay).

Most well pumps can't move water that far up a pipe in one go, so likely there will be a need for several pumps along the total length of the pipe. One of these units might produce 1500 gallons per day (this is a REALLY rough guess, based on the data for one reverse osmosis filter specification), so you'd need several of these units to supply a community, and there is the consideration of maintaining the RO membranes, which might kill the overall efficiency of the system. Still, I find there is a certain attraction to the idea of drilling a hole in the middle of the ocean and pulling fresh water out of it.

Wave Powered Water Distiller

The second notion honestly came to me when considering how a country could extract fresh water from the Red Sea. In that case, I was thinking about Jordan. Later on, I adapted the idea as a method of supplying water to the people of the Gaza Strip, such that they could supply themselves with an uninterruptible supply of water, preferably using a low maintenance, low cost device. Essentially the idea is simply to create a heated chamber for near-vacuum distillation of sea water. A tallish-chamber is located on a pier. It is heated by the sun. The bottom of the chamber is open and is stuck in the sea water below the pier. A wave powered pump sucks air out of the chamber, causing the sea water to be sucked in through the chamber's bottom opening. If the chamber is a bit over 32 feet tall, the water will never be able to reach the top of the chamber, due to there being a total vacuum above the water. The water in the top of the chamber will just about be boiling due to the vacuum.

As the pump continues to maintain the vacuum in the chamber, the pump outlet will be driven into a pipe, which drops into a cooling tank, located below the surface of the sea water, below the pier. With the increase in pressure and the drop in temperature, the steam collected from the boiling water of the evacuated chamber will condense into water. While this solution might have efficiency problems, at least it wins for using free energy for driving the process.


These are two ideas that I think would be worthwhile checking out. One of my concerns for traditional desalinization plants is they are energy intensive and destructive to any creatures which get sucked into them. Supplying loads of energy to a desalinization plant seems counter-productive, as you use a fair amount of fossil fuels and potentially water, to supply that energy. The thought with both of my solutions is that they are relatively economical, energy-wise and have low impact on the surrounding marine environment. Even the distillation unit, with it's open ocean access, gives creatures the option of swimming back out of chamber rather than facing vacuum and higher salinity, and even a simple screen would prevent most aquatic tragedies. It is my hope that people figure out how to get their water without further straining our environment. These ideas are my attempt to facilitate that hope.

Friday, November 14, 2014

Philae takes P67 Surface Pic

So here's a picture from the surface. What science we'll be able to collect is somewhat problematic as the probe landed in a place where sunlight only gets to the solar panels for about one and a half hours a day. This is a bit too little to maintain battery life, so there is a limited window to collect data before the 30 hours of battery life in the probe come to an end. Hopefully some good chemical data can be gathered prior to that time.

Wednesday, November 12, 2014

Another Rosetta Milestone: The Philae Lander is on the Comet

So the big news this November 12th was the first landing of a craft onto the surface of a comet. The ESA's Rosetta mission was launched ten years ago in order to rendezvous with a comet and drop a landing craft called Philae onto its surface. Comet 67P or Churyumov–Gerasimenko, is a short period comet, which has an orbit that ranges from a distance between Mars and Earth at perihelion to a bit beyond the orbit of Jupiter at aphelion. This relatively close-in orbit made the comet especially attractive, as the energy requirements to get to the comet and match speeds with it were very modest. Rosetta achieved orbit around the comet on August 6th, 2014. Initial images of the comet revealed a spinning, rubber-ducky shaped nucleus about 5km long on a side.

One can only imagine the nightmare of trying to figure out where to drop the Philae lander so it wouldn't get bashed by the comet's various protuberances. Philae separated from Rosetta at around 1:03 AM PST (9:03 GMT) this morning, and reported that it had made contact with the comet at around 8:03 AM PST (16:03 GMT). The image at the top of this blog entry is the view from the Rosetta Spacecraft looking towards the just released Philae lander. The image below, was taken by Philae, looking back at the Rosetta spacecraft. Interesting perspectives. We can't wait to see the images from the comet's surface.

Tuesday, November 11, 2014

JPL Scientists Planning to Probe Uranus

I was doing some browsing today on the Falcon 9 Heavy and comparing it to NASA's SLS heavy lift launcher, when I came across this tidbit on proposed future missions enabled by the SLS. FWIW, Falcon 9 heavy will be capable of placing 53 metric tons into orbit, while NASA's SLS should be able to lift between 70 and 130 metric tons to orbit. Clearly SLS has a much greater capacity, but one might have to ask how much more expensive is it by comparison. At any rate, a proposed mission for the SLS is an eventual mission to Uranus, as proposed by NASA's Outer Planets Assessment Group. In a 2013 presentation, JPL's Mark Hofstadter advocated for a Uranus mission and outlined some scientific goals of such a mission. This was then reported in a story in American Space authored by Leonidas Papadopoulos titled, "New Mission Concepts for SLS With Use of Large Upper Stage" as the following:

A dedicated Uranus orbiter has also been the longing of the planetary science community. A Uranus orbiter is listed as the third highest priority Flagship mission after Mars and Europa in the 2013-2022 U.S. Planetary Science Decadal Survey. Dr. Mark Hofstadter, a planetary scientist at NASA’s Jet Propulsion Laboratory, stressed that point during a presentation at the January 2013 meeting of the Outer Planets Assessment Group, in Atlanta, Ga.

In other words, JPL scientists have been longing to probe Uranus, and apparently been doing so for quite some time. This may come as quite a shock to many of you readers. I know it's not April first, but given the tragedies of the last few weeks, perhaps now is a good time for a bit of scientific levity.

Monday, November 10, 2014

Rick Tumlinson: On "Interstellar" and the Virgin Galactic Accident

Rick Tumlinson, one of the founders of the Space Frontier Foundation wrote a brilliant piece in Huffington Post about both the risks and the hopes of space exploration and colonization, highlighted using the disasters of Cygnus/Antares launch failure and the Virgin Galactic accident and a glowing review of the movie "Interstellar".

Rick oozes the spirit of the space advocacy movement. His review of Interstellar is practically poetry. His passion for space advocacy is infectious:

"That is the inherent and divine irony of the frontier movement. Our cause, while built and riding on the same technologies that may yet kill this world, the harnessing of fire and energy and electrons and blatant challenging of the skies themselves on pillars of flame and fire, is based on the most beautiful of dreams.

We in this movement believe in life. We love this world. We love humanity and believe that far from a ravaging blight, we are indeed the seed carriers of this precious planet. "

I'm not sure I'm completely in agreement with Rick on everything. Sometimes I think humanity is far more blight-like than planetary life-savior-like. But I don't blame humanity for this. Any apex species would do the same, unless a strong inner sense of "noblesse oblige" prevented it. But I agree with Rick that humanity is more than capable of being a force for good.

At any rate, read Rick's article. I enjoyed it and found it most satisfying.

Friday, November 07, 2014

Sad Happenings in Mojave

Image courtesy Guardian Media

By now everyone has heard about the tragic crash of Virgin Galactic's Spaceship II in Mojave, California. One pilot died and one pilot was severely injured in the accident. They were both test pilots, so they knew there was risk in what they were doing. Still, it was a terrible loss for Scaled Composites and for the Mojave Aerospace Community. The Mike Alsbury Memorial FundM was set up to help support Mike's wife in her time of need. Please contribute, if you feel so inclined.

As far as the accident is concerned, here's what we know: The NTSB has concluded that the in-air destruction of Spaceship II was due to Spaceship II's "tail feathering mechanism" opening during powered flight. This is the mechanism Spaceship I and II employ to re-enter the atmosphere during the ship's return to earth from extreme high altitude. This is done to present a large flat surface towards the flow of air and increase the rate of deceleration. Since the tail feathering places the ship's fuselage (and thus the rocket engine) perpendicular to the flow of air, the effect of activating it under thrust was to tear the ship apart. Many people had feared that the engine of Spaceship II was to blame, but it seems that has turned out not to be the case.

What ever the cause of the accident. I hope Virgin Galactic gets back on their feet soon. Obviously they will need to do much more testing before flying paying customers.