December 18, 2017

09.04.11: 2010 SO16-A World in a Bizzaro Orbit.

A horseshoe orbit. (Credit: NASA).

Ever wondered what local space would be like if the Earth had more than one moon? Well, it turns out that we do have several natural interlopers; sort of. Recently, researchers A.A. Christou and D. J. Asher of Armagh Observatory in Northern Ireland reported on the discovery of a unique Near-Earth Asteroid (NEA): 2010 SO16, a 200-400 meter space rock locked in a horse-shoe orbit with Earth. [Read more...]

03.04.11: Alien or Aeolian?

The humble terrestrial sand dune…(Credit: Art Explosion).

This sunny Sunday morning, we’d like to point you towards an astro-video that floated through our cyber-transom. We’ve recently discovered the SETI Talks series on YouTube, and have become a hooked subscriber. These weekly talks feature a broad range of astronomers and researchers and are a fascinating look at cutting edge science as expressed by the scientists that are doing the research. [Read more...]

17.03.11- Mercury: At Last!

Brave New World: Mercury as seen from Messenger during 2nd flyby departure.

 (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington) 

Tonight marks a pivotal moment in solar system exploration. At 12:45 AM UTC on March 18th, NASA’s Mercury Messenger spacecraft will burn its engines for approximately 15 minutes to enter an elliptical orbit around the planet Mercury. Since its launch from Cape Canaveral on August 3rd, 2004, Messenger has flown by the Earth once and Venus twice for a gravitational assist, swung by the innermost world three times, sampled the near solar environment, searched for Vulcanoids, and even done a wide field pan for any tiny Mercury moonlets that may have been missed. [Read more...]

03.06.10: Do “Dirty” White Dwarfs Provide a Key Spectral Signature?

 

If astronomers at the Leicester University in the United Kingdom are correct, the key elements and chemicals that comprise life may be common throughout our Milky Way. The evidence comes from an unlikely source; spectral examinations of populations of galactic white dwarfs. These ancient remnants of stars exist in vast numbers, and our Sun will indeed share their fate one day. The study, led by researcher Jay Farihi, looked at over 100 million objects in the Sloan Digital Sky Survey, which provides a map of the sky and our galaxy as seen in the infrared spectrum. Their findings conclude that up to 20% of all white dwarfs surveyed are contaminated with trace metals, most likely the result of interplanetary debris. In the field of astronomy, the term “metal” refers to anything that isn’t hydrogen or helium, a little different definition than what you learned (hopefully) in high school chemistry. The thinking goes that where heavier elements are seen, terrestrial planets and perhaps life may be sure to follow. Our Sun itself is a good case in point; a Population I star that is relatively metal rich, allowing for a large retinue of rocky planets, including the Earth. How common or rare we are is still hotly debated, but this analysis of the atmospheres of white dwarfs may prove that terrestrial worlds are perhaps abundant throughout the cosmos.  In terms of this study, astronomers are in a sense looking at the “ruins” of older terrestrial systems that will be recycled and incorporated into new, metal dense populations… perhaps one could argue that as time in universe marches on and heavier elements become more abundant, the odds are that life will become more frequent, at least until the stelliferous era runs its course!

Review: How to Build a Habitable Planet by James Kasting.

Some years ago, a book entitled Rare Earth was published amid much controversy. The central thesis of this work was that events that led to the eventual habitability and diversity of life and intelligence on Earth were so improbable, as be near to impossible to replicate elsewhere in our galaxy. The book marked a sort of change in thinking in the realm of exobiology, one from “intelligent civilizations are everywhere” championed by the late Carl Sagan to the concept that we may be the only ones, if not the first.


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24.04.10-Our Existence: Justified.

The formation of the Earth poses a key dilemma to planetary accretionary theory; namely, why are we here at all? Standard models would say that the Earth and other planets coalesced out of the proto-solar nebula to form. However, spiral density waves within the same nebula should have drawn down orbital energy to shorten the planets orbit, slowly drawing it in. Looking at other “hot Jupiter” systems, that’s just what we see; large gas giant worlds that formed further out, only to migrate inward into tight orbits… just how did we end up in our nice, neat orbit?

Now, computational astrophysicist Mordecai-Mark Mac Loc at the American Museum of Natural History may have the answer. Accounting for temperature and spin variability, resonance key holes can occur; planets like Earth may simply spiral inward and get hung up in these safe zones between dragging pressure waves. Of course, a majority of proto-planets don’t make the cut and simply spiral inward to a fiery end, but they’re not around for us to see today. One discovery that would perhaps give observational weight to this theory would be the discovery of exo-Earths also parked in nice neat orbits… the Kepler space telescope may pave the way for this discovery as it stares off into Cygnus. For now, thank computational mathematics that you’re here reading this, just as it says you should be!

11.04.10- Pale Blue Crescent.

It has been said innumerable times that in traveling into space, we’ve discovered the Earth. The Rosetta spacecraft reminded us what a unique place our home is on its trajectory altering flyby on November 13th of last year. Pictured above, you can easily tell that Earth is not a stagnant world, but a dynamic place, a place where interesting things are constantly happening. When the first astronomers looked at other planets in our solar system, it was thought that these worlds might not be any more hostile than, say, Antarctica. This concept still pervades some of the more campier of science fiction worlds, even today. But our explorations of the solar system have shown us something different, that even, say, a balmy day on Mars is magnitudes more hostile than Earth’s Gobi desert.

The European Space Agencies’ Rosetta spacecraft continues that spirit of exploration. Launched in 2004, it has performed a complex series of orbital slingshots that will cause it to eventually arrive at comet 67P/Churyumov-Gerasimenko in May 2014. There, it’ll take measurements of the icy interloper and even deposit a lander on the surface of a comet for the first time. Last year’s passage was Rosetta’s third and last flyby of its home world. The spacecraft had just passed asteroid 2867 Steins the year before, and is slated to perform a reconnaissance of asteroid 21 Lutetia in July of this year. The close passage with Earth gave it a 2.2 mile per second kick towards its final objective.

Do give pictures like those sent back by Rosetta pause, as we are the first and truly privileged generation to see our home world not as we’d like to see it, but as it actually is. Hey, we’re all on this Big Blue Marble together… perhaps we can get jaded by anything in time, but sights like these give us hope for our  survival as a species!

10.04.10- Radio Astronomers Refine Celestial Grid.

Getting a good fix on positions both on the Earth and in the sky is tougher than it may sound. Tectonic plates move. The Moon raises tides under our feet. The whole planet orbits our Sun, which is itself flying about the galaxy and getting jostled by other stars, as the galaxies themselves are flying apart. Last year, however, astronomers at the National Science Foundation’s Very Long Baseline Array of radio telescopes tackled the problem in a novel way. Using 35 radio telescopes worldwide, they monitored and measured the positions 243 quasars over a 24 hour period starting November 18th 2008. Quasars are ideal candidates for this kind of measurement because of their extreme distance. These high precession measurements break the old record for the most radio dishes employed, which stood at 23. The telescopes utilized a method known as Very Long Baseline Interferometry, which combines simultaneous signals collected over individually spaced telescopes to increase resolution power. Headquartered in Socorro, New Mexico, the VLA’s data will not only refine astronomical measurements, but increase the accuracy of geophysical science as well.

04.11.09:Did Ancient Comets give Earth its Seas?

Comets continue to be at the center of controversy concerning the early Earth and life. If you’ve been following our recent reports as of late, you know that opinions run the gamut, from ancient cometary impacts being relatively rare, to comets being crucial to life as we known it. Now, researchers at the Niels Bohr Institute in Denmark have scored one for the comet camp. Recent studies of ancient rocks in Greenland suggest that the primordial Earth may have undergone a massive cometary bombardment early in its history, about 3.85 billion years ago. Were talking waaaaay back in the Archean period, before life had even taken hold. The conclusion is based on our friendly elemental smoking gun, Iridium. Rare on Earth, what little iridium is found in the Earth’s crust is almost certainly of extraterrestrial origin. Asteroid impacts generally distribute about 18,000 parts per trillion, while comets, due to a higher impact velocity and icy rock composition, produce amounts much lower, about 130 parts per trillion. The team found a ratio of 150 ppt, strongly suggesting that comets were the primary constituents of the Late Heavy Bombardment. This is a tantalizing clue in two enduring mysteries concerning the early Earth; how did we our get our large oceans, and how did life start? Looking out into the solar system, we are the only planet with a large surface covering of liquid water. Could it have been deposited by comets? That’s a lot of dirty snowballs… there is some thought that life itself, or at least amino acids, known as the chemical building blocks of life, might have been deposited in the same fashion by a method known as panspermia. Not all scientists remain convinced, however, and for now, spinning cometary hypotheses remains a sure way to generate scientific controversy. Are we all “comet-stuff?”

 

22.10.09: Thank Relativity that We’re Here!

The next time you’re studying the Lorentz equation or are forced to account for Relativity on your Buzzard Ramjet trip to Sirius, thank Einstein that we’re here at all! Scientists Jacques Laskar and Mickael Gastineau at the Paris Observatory have been modeling orbital dynamics in our solar system and have come up with some “disturbing” results. It has long been known that Jupiter has a shepherding effect on the inner solar system, smoothing out planetary orbits while ejecting or sweeping up incoming debris. However, if you model the planetary orbits taking into account only classic Newtonian motion, the odds that Mercury goes out of whack in the Sun’s 10 billion year odd life span are about 60%. Throw in Einstein, and the effect shrinks to less than 1%. A careening Mercury would be a bad thing; if it impacted Venus, we would get showered with debris over a million year span, and if it hit us, well, it would just be a bad day. The best thing it could do is harmlessly impact the Sun. Even a near miss with the Earth could drastically alter our orbit, not to mention tinker with our stabilizing Moon. Fortunately, the tiny tweak that the Sun’s gravitational well gives Mercury’s eccentric orbit via General Relativity assures that a resonance keyhole with Jupiter’s orbit probably won’t happen. Keep in mind, we’re talking tiny effects that pile up over billions of years… every time an asteroid whizzes by, we launch a Space Shuttle, or LeBron performs a slam dunk, the Earth gets a tiny push. Over billions of years, tiny forces do add up (ever heard of the Butterfly Effect?) This is why astronomers cannot predict the positions of planets more than a million or so years into the future. Incidentally, the precession of Mercury’s orbit still stands as one of the great observational proofs of Relativity. One also wonders if such a perturbation might have been the fate of Theia, the Mars sized impactor that has been hypothesized to have struck a prehistoric Earth and created our Moon. So the next time you see gravity bend light at relativistic speeds, thank Einstein for protecting our home planet Earth!

17.10.09: Pondering the Possible Fate of the Earth.


Colossus-The Forbin Project: a Sci-Fi classic that kicked off the talks!

What’s the future of humanity and life on Earth? Will we have a good multi-billion year run until our Sun swells into a red giant boiling away our atmosphere, or will we first do the job of snuffing ourselves out? Earlier this year, some of the leading thinkers of our time gathered near Harvard University at the Arrow Theater to discuss just these weighty concepts. Dubbed Crossroads: The Future of Human Life in the Universe, each talk in the series was 30 minutes long and solicited an avalanche of enthusiastic questions. Some of the highlights:

-Gerrit Verschuur discussed the Drake equation and just how prevalent any interstellar neighbors might be; at a guesstimated 2,500 light years, we may be pretty, well, spaced out!

-Maira Zuber discussed the future of space travel in the solar system and the difficulties of overcoming probably the biggest engineering problem; prolonged radiation exposure.

-Astronomers Dimitar Sasselov, David Charbonneau, and paleontologist Peter Ward of Rare Earth fame discussed the slew of recent exoplanet findings and the quest for the true coin of the realm; Earth-like worlds around other stars. Most interestingly, the idea was proposed that a “super-Earth” may be more conducive to the development of life, and our own planet may represent the bottom rung of habitability; indeed, as Ward notes, “Rare does not mean unique!” Another interesting proposal by Ward is what he termed the Medea Hypothesis, a sort of anti-Gaia Hypothesis, were the Earthly biosphere may actually occasionally become detrimental to life, and thus fuel mass extinctions. The name comes from perhaps the worst Mom in mythological history!

-Finally, big time elder thinker Freeman Dyson of Princeton urges that our very search methods for life might be flawed, and that we should be looking for “what is detectable, rather than only whats probable.” he also proposed missions targeting such possible abodes for life such as Europa, the icy large moon of Jupiter.

Whatever the future of humanity is, one gets the impression from the visionary speakers presented that it is NOT endless consumerism. The message in the history of life on Earth is clear; evolve or die. No one will save us but ourselves, and the future is collectively ours to choose!

14.10.09: The Earth-Moon System as viewed by HiRISE.

The image above floated through our tweet-o-sphere yesterday, thus prompting today’s news post. HiRISE, NASA’s High Resolution Imaging Science Experiment aboard the Mars Reconnaissance Orbiter(MRO) is the spacecraft that you’re probably not following, but should be. In orbit about the Red Planet since early 2006, its been transmitting some pretty mind blowing images, all definitely worth a daily peek! Housing a 0.5 meter reflecting telescope which would be the envy of any backyard astronomer, its the first true “spy satellite” quality orbiter that we’ve fielded about Mars. Able to resolve targets about 0.3 meters across, some of the highlights have included stunning views of the polar caps and dunes, snapshots of the Opportunity and Spirit landing sites, and even catching the Phoenix Lander in descent! In fact, eagle-eyed desktop amateurs may even prove successful it divining the fate of the many (more than half!) errant Mars-bound landers over the years. But as is often the case with space exploration, we travel millions of miles to find…ourselves. Some of the most memorable images are actually those of the Earth, whether its “Earth-rise” aboard Apollo 8 or the “Pale Blue Dot” as viewed from Voyager 1, images such as these and the HiRISE pic above of our tiny home remind us how special our place is. Snapped back in 2007, it shows us that the Earth is not only a pretty, but dynamic place were things are happening. Mars is tiny and cratered, and through a backyard telescope, generally yields little detail. Venus, although dazzling, is perpetually shrouded in sulfurous cloud. Not so with the Earth. Cloud cover changes, the surface shows a variation in sea, land, and seasonal growth, and at night, an experienced telescopic eye might just pick out the lights of cities, evidence of human activity. Views like this always remind me of Arthur C. Clarke’s little known but classic short story Report on Planet Three, where Martian scientists argue that life couldn’t exist on Earth! Clarke wryly points out that life elsewhere may not be remotely Earth-like. I personally can’t wait to spread my telescope tripod legs out under a night under Martian skies; and without a doubt, the slender crescent Earth-Moon duo will be my first astronomical target!

 

12.10.09: NASA Battles Bacteria in Space.

Astronauts have been growing Salmonella bacterium in orbit, and the results have been astounding. Missions STS-115 and 123 to the International Space Station performed the experiments, showing that the bacterium were up to 7 times more virulent when grown in zero-g than on Earth. The likely culprit; fluid shear, which mimics the environment found in the human gut. But there is more weirdness; add potassium or chlorine ions, and the virulence levels off! Such is the wackiness of cells… Why study microscopic bugs in space? Well, these experiments enable researchers to map the genome of these bacterium by following their explosive growth and also to identify “master switches” such as the protein Hfq that controls certain genes… this in turn will lead to designer drugs in the quest to stay ahead of evolution in the antibiotics battle.

 

Astro Event of the Week; November 10th-16th; The Launch of STS-126.

One of the very few remaining shuttle launches will be occurring this week; STS-126 is scheduled to launch on November 14th at 7:55 P.M. EST (yes, another spectacular night launch!) and dock with the ISS on Day 3.

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Free Tools for the Renegade Scientist.

The motto here at ye’ ole Astroguyz could be “never pay good money for what you can snark for free online”…many a good stone has been spent on tools or applications that can be found, with a little thought, for free online. [Read more...]

Measuring the Circumference of the Earth: the Eratosthenes Method

  This is one I duplicated in High School that I first heard about on Carl Sagans’ Cosmos series.  Way back in the 3rd Century BC, the Greek philospher Eratosthenes of Cyrene devised a method of calculating the circumference of the Earth. [Read more...]