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05/05/2014
More from Ouit in Space
CHAPTER 45 Kepler Keeps On Giving
I'm late in posting this column and blame it on a lousy April. We didn't have any major snowstorm but it was certainly not spring-like weather. And we didn't get the April-ending horrific rain that some places in the South experienced, but we did get enough here to water our basement despite our two sump pumps doing their best to expel the water. Overlapping our wet basement, we've had painters working on the outside of our house and it's been hell for my wife, enduring the sanding and hammering to remove storm window frames. The overwhelming noise has not been conducive to writing a column.
Perhaps what happened on Easter best characterizes our April. Actually, let's go back to the day before Easter. I had not yet mailed a form for something pertaining to the Robert Wood Johnson Medical School, now under the Rutgers University umbrella. The form was to formalize my decision to donate my body to the medical school when I die. Years ago, when I was consulting there, I was returning from lunch in the cafeteria and in the student rec hall they were having an impressive candlelight ceremony honoring those who had donated their bodies. OK, back to Easter. When I awoke Easter morning, I had a severe pain in my right leg unlike any I'd ever had. I was drenched in a cold sweat and also had lost control of my bladder! I really felt that I was going to die and my first thought was that I hadn't sent in that blasted form! With my wife essentially wheelchair bound, I managed to drag myself out of bed and downstairs after calling 911 and our editor, Brian Trumbore. Brian arrived as I was being secured in the ambulance for the ride to the ER. Well, to make this short, all my blood and urine tests were normal and the doctor said it was most likely a muscle spasm and I was back home in less than four hours. Thankfully, our daughter-in-law had scheduled that she would come to our house and cook the Easter dinner. It was great. However, I won't go into detail about the day ending with my wife having her own medical episode.
I should be writing something of a technical nature instead of burdening you with my personal problems. Let's try electric vehicles. Coming back from my morning walk at our mall recently, I found myself driving behind a Tesla, the lithium-ion battery-powered automobile ranked so highly by Consumer Reports. I was hoping the owner might stop somewhere in my neighborhood so I could ask his opinion of the vehicle. No such luck. Tesla has a dealership in our mall but, unfortunately, we seem to have a law here in New Jersey that mandates autos be sold only through franchised independent dealerships. Apparently, dealing directly with the customer, as Tesla does, is not allowed and unless something happens, Tesla will not be allowed to sell cars in NJ. Our embattled Governor Christie protests that he's only enforcing the law if he has to eject Tesla from the state. I have seen a press release from an automobile dealers association emphatically defending the law but I'm not persuaded it's a good law.
Over five years ago (see archives 10/30/2008), I wrote about Tesla and expressed concern about the safety of using lithium batteries to power a vehicle. I also noted that the Tesla battery contained thousands of the same size lithium-ion batteries used to power your laptop. Much to my surprise, on looking up the Tesla Web site, I find that Tesla is still using the same 18650 (18 millimeters in diameter by 650 millimeters in height) cells they were using back in 2008. The Tesla Roadster employs a battery containing 6,831 of these cells, which are not that much larger than your standard AA cells! The battery pack weighs 990 pounds, stores 56 kWh of electrical energy and can deliver up to 215 kW of power. Tesla emphasizes the extensive testing and attention paid to safety with regard to the lithium-ion batteries and, I must admit, with Elon Musk a key player in the Tesla story, I'm impressed.
Within the past week or so, I saw an article somewhere saying that Musk and his SpaceX endeavor are now involved in trying to come up with a reusable rocket. The success of SpaceX in delivering supplies to the International Space Station has certainly been a feather in Musk's hat. Somewhere else I've read that he is seriously interested in getting involved in a manned trip to Mars. I've written in the past about my skepticism concerning such a venture in spite of my obsession with anything related to space and our universe. Although I certainly won't be around to see such an achievement, I wouldn't be surprised if Musk is involved in achieving that goal.
I'm trying, of course, to segue into recent space-related achievements that I'm obliged to consider. When NASA announced that the Kepler mission of finding planets outside our solar system had ended about a year ago with the failure of key components of the satellite, NASA also stated that scientists still had plenty of Kepler data to keep them busy for years to come. Well, just look at the title of a paper in last month's April 18 issue of Science: "An Earth-Sized Planet in the Habitable Zone of a Cool Star". Certainly, the Holy Grail of the Kepler mission was not only to find planets, which it has done in spades, but the ultimate goal was to find an Earth-sized planet in the habitable zone of a sun-like star. Kepler has found dozens of planets orbiting in habitable zones of stars but to date, those reported have all been either large gas giants or a few larger planets that may or may not be rocky bodies.
What Elisa Quintana and a host of other authors report in Science is that Kepler-186, a low mass dwarf star less than half as big as our Sun, is surrounded by five planets. All of these planets are Earth-sized or even smaller and just finding such small planets is a remarkable achievement. However, four of these planets orbit too close to the star to support liquid water, the main criterion for a habitable zone. The fifth and outermost planet, Kepler-186f, is within 10-20 percent the size of Earth and is in the habitable zone. Because the star is less luminous than our Sun, the researchers consider Kepler-186f to be more of a cousin to Earth than a twin. Unfortunately, the planet and its star are 500 light-years from Earth and that's apparently too far for any follow-up studies, such as trying to determine what its atmosphere looks like. Hopefully, the Kepler data may yet reveal a closer solar system with an Earth-like planet.
In the same April 18 issue of Science, Ethan Krus and Eric Agol of the University of Washington have mined the Kepler data for a different kind of result. Recall that Kepler detects planets by observing the dimming of a star's light when a planet crosses between us and its star. Well, what happens when the Kepler data show a periodic brightening of a star's light, not a dimming. As often happens in these columns, enter my scientific hero, Einstein. His general theory of relativity predicts that gravity bends light. For many years astronomers have used this bending of light to explain and exploit the lensing effect of massive bodies, say whole galaxies, to magnify images of stuff, say other galaxies, lying farther out behind the intervening galaxy.
OK, let's look at an object of interest, Kepler Object of Interest 3278, KOI-3278. I gather the KOI term is used to designate a planetary candidate. However, in the case of KOI-3278, it is not a planet that is orbiting a Sun-like star. It's a white dwarf star, not an unusual situation. It seems that over 40 percent of Sun-like stars are bound up in binary or multiple star systems. I guess we're lucky that our Sun just has us planets to worry about. When that white dwarf passes between its companion Sun-like star and us on Earth, the white dwarf's mass, about 63% of it companion's mass, is sufficient to bend the light and amplify it by only one part in a thousand (0.1 percent). Not much, but thanks to Kepler's sensitive instruments, that's enough to verify a prediction made by Andre Maeder in 1973 that such a binary star system could show repeated magnification if the orbit is viewed edge-on. Just what Kepler was designed to do in its planetary search.
One final space item. Water. In the years I've been writing this column, one thing that has impressed me is the fact that water, essential to life as we know it, is not an unusual substance in the universe, especially in our own solar system. I've expressed the view that, instead of concentrating on Mars, we should be concentrating on Jupiter's moon Europa, thought to have an ocean under its surface, in our quest to find life of some sort. Several years ago, jets of water were found emanating from the South Pole of Saturn's moon Enceladus. Last month, NASA announced that the Cassini spacecraft had made precise gravitational measurements that indicate Enceladus has an ocean, under a substantial ice shell. I was intrigued with the way the gravity studies were done. Cassini communicates with NASA's Deep Space Network and the tug of the gravity alters the speed of the spacecraft as it sends signals back to Earth. The change in velocity leads to a Doppler effect that causes a change in the radio frequency of the signal. Changes in velocity of less than a foot per hour can be measured - very impressive.
Hopefully, May will be a better month and the next column will be posted closer to June 1, 2014 than it was to May 1.
Allen F. Bortrum
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