April 5, 2020

Review: Mars, Inc. by Ben Bova

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It’s a destination that always seems to be “20 years away.”

But just how will we get to Mars? And why should we go? Science fiction author Ben Bova’s most recent book Mars, Inc.: The Billionaire’s Club out from Baen Books shows us just how those first steps might be made. [Read more...]

Astro-Vid Of the Week: The Transit of Deimos

Phobos & Deimos as seen from MSL

Credit: NASA/JPL.

(Click here for full size view).

This past week saw the celebration of the one year anniversary of the landing of the Mars Curiosity rover at Gale crater. In just one year, the SUV-sized rover has revolutionized our understanding of the Red Planet.

And although it’s equipped to be a geologist, the Mars Science laboratory (MSL) has been a surreptitious astronomer on occasion as well. We routinely comb through the MSL camera archive and were recently surprised to find an image of the Martian Moons of Phobos and Deimos in one frame! [Read more...]

April 2013: Life in the Astro-Blogosphere: Astronaut or Rockstar?

1st band in space? (Credit: NASA/STS-110).

What did you want to be when you grew up? Of course, this tired old saw of a question assumes that you’re already a mortgage-paying, car-pooling adult who has had those childhood dreams tempered by reality. Hey, we all know that one guy or gal in our home town that got exactly what they wished for. For example, I knew a friend in high school that spent every waking hour drawing, designing and talking about car stereo boxes… and guess what? That’s what he does to this day. (Hopefully, the whole Ipod thing didn’t ruin his grandiose business schemes). [Read more...]

Astro-Event: The Red Planet Meets the “Anti-Mars.”

All hail the “Anti-Mars!”

No less than two astro-events mark the passage of Astronomy Day on October 20th, a day so cool, we repeat it twice! The other Astronomy Day on the calendar for 2012 was on April 28th. (Hey, the sky changes, y’know?)

First up, the planet Mars meets the bright star Antares (a.k.a. Alpha Scorpii), passing just over 3° degrees to its north on the 20th. Mars has added an appreciably different look to the constellation since passing into Scorpius and sliding by Delta Scorpii on October 10th. Coincidentally, now is a good time to compare Mars and its astronomical antithesis. [Read more...]

A Look at the Earth’s Interior.

Eruption! Our active planet as seen from the Aqua satellite… (Credit: NASA).

(Note: The essay that follows it part of a series of papers I wrote in my quest for my science teaching degree… I always hate the fact that school writing only makes it to two sets of eyeballs, mine and the graders, so I re-worked my writing a bit for the blog format…)

The Earth is the only terrestrial planet that we have the availability to reach out and examine up close. By use of painstaking scientific processes, we can monitor the inner workings of our world and create a model of its interior structure that presents a high degree of accuracy with what is observed. Still; while we live on its surface, we have never penetrated the shell of even its outer crust or sampled its deep interior… just how do we know what’s within?

To map the Earth’s interior perhaps no tool is more essential than the seismograph. Also sometimes referred to as the seismometer, this device is essential for recording and monitoring seismic waves in the Earth’s crust and their passage through the interior. This device usually consists of an internal inertial mass that is deflected relative to an external frame, usually anchored to the surrounding bedrock. As the device is shaken, the mass is moved as waves pass through it, deflecting a needle against a scrolling spool of paper marking the passage of time. Early detectors were constructed during the Chinese Han Dynasty. Modern detectors may be on the classic needle deflection type or digital and utilize the precise measurement of laser beams or a mass magnetically suspended generating a negative feedback loop. Key waves detected are P, or primary waves, S, or secondary waves, and surface seismic waves.  P waves are the initial “push-pull” waves of an earthquake. These are the fastest waves, and thus the first recorded during a seismic event. An elastic wave, P waves can travel through any medium, be it solid, liquid or gaseous. These waves are compressional and can also vary with the subsurface depth of the earthquake. Next waves to arrive are the S, or shear waves. Also known as transverse waves, these are slower moving and can only travel through solid material. Finally, the surface waves are the last to arrive at a given detector, as they are slower moving and generally cause the most damage. If these waves can be recorded by three separate detectors spaced out on the Earth’s surface, a precise epicenter can be pinpointed. Also, the fact that an Earthquake shadow zone is generated where only P waves are seen is prime and well documented evidence that the Earth’s outer core is not solid, but molten. Indeed, the magnetic shear or torsion generated by the interplay of Earth’s iron-nickel solid core, and liquid molten outer core, is further evidenced by our relatively strong magnetic field. In comparison to the Moon and other terrestrial or rocky planets, the interior of the Earth is a dynamic place, and seismology helps us understand this differentiated structure.

(Created by Author).

Elements of seismograph construction may include a digital strong-motion accelerograph or several inter-connected seismometers working to create one coherent output. A classic earthquake will first register on a seismogram as a series of short spikes marking the initial P-waves. Minutes later, the first S-waves will arrive spanning a slightly longer period of time. Finally, the largest and most damaging surface waves arrive. As seen on a seismograph, the timing and spacing recorded at an individual station may vary depending on the depth and distance of the earthquake epicenter.

The science of seismology is crucial to understanding the interior structure of the Earth as well as predicting where damaging earthquakes or tsunamis are likely occur. This study is vital to the whole Earth model because although we cannot directly sample interior layers of the Earth, we can model them by examining the speed and types of waves that transverse the crust, silica rich mantle, and inner and outer cores.

The outer surface of the Earth is composed of tectonic plates that either converge, or subduct one under another, diverge or separate, or strike slip or grind past one another. This type of surface material recycling drives what’s known as the rock cycle. The outer-most rigid crust is known as the lithosphere, which is comprised of the crust and a layer of brittle and solid rock about 100 km thick. This crust is thickest on the continents, and thinnest underneath the oceans. Of special interest is a separation known as the Mohorovi?i? Discontinuity, first discovered in 1909. This boundary between the crust and the Earth’s mantle was deduced by studying the refraction pattern of earthquakes by shallow p-waves.

Farther down, the lithosphere rides along top of the flexible and molten asthenosphere. This layer extends down to a depth of about 400 miles and is mechanically detached from the deep lower mantle. Again, only P-waves can travel through molten regions of the inner Earth; S-waves cannot. This key fact is prime evidence that the outer core of the Earth is fluid, or molten. Likewise, the refraction and reflection of seismic waves can also provide us with a “look” inside the Earth to probe its interior.

But beyond the probing of Earth’s interior, the study of seismology is crucial to other applications, both scientific and economic. The study and conduction of seismic waves can be applied to locating large fossil fuel deposits as well as prime aquifers or areas of potential sink hole activity. Again, this utilizes our understanding of the transmission, reflection, and refraction of P- and S- waves through solid versus liquid and gaseous material. Seismology is also used to detect nuclear weapons testing, and to assure compliance with test ban treaties. The liquid outer core is further evidenced by the creation of Earth’s magnetic field. When we look at smaller, cooler bodies such as the Moon and Mars, little evidence for a magnetic field is seen; in fact, the low density of the Moon versus its size is prime evidence that it was once part of the Earth’s crust and mantle ejected by a massive impact. Igneous basaltic rocks brought back from the Moon by Apollo astronauts support this theory. Finally, seismology demonstrates evidence for plate tectonics by showing observational proof that the plates of the lithosphere are active and in motion. Plates snapping back into place or grinding past each other all generate massive amounts of seismic waves in what we know as earthquakes. Over time, these cause the raising of great mountain ranges such as the Himalayas or massive earthquakes such as were recently witnessed in Haiti, Chile and Japan.

In conclusion, seismology and the study of seismic waves are key examples of how we can study something in science without directly examining it. Beyond just scientific interest, this has given us such benefits as the Pacific Tsunami Warning Center that has saved countless lives. As we move out and study other planets in our solar system, knowledge of the interior structure of the Earth will give us some insight into comparative planetary science and just how common or rare a dynamic place like Earth truly is.

26.05.11: Farewell, Spirit…

Spirit: A self-portrait. (Credit: NASA/JPL).

This week, amid news of distant gamma ray bursts, daring spacewalks, and spacecraft redesigns, a small story came our way of the end of an era; earlier this week, NASA announced that it would no longer attempt to hail the Spirit Lander on the surface of Mars. [Read more...]

AstroEvent: 2xBright Planets in the Dawn Sky.

Jupiter, Venus, & Mercury+a 1 degree FOV on the morning of May 11th.

(Created by the author in Starry Night).

The planetary conjunctions reach a climax this week, with a close apparent pass of the two brightest worlds in our solar system, Jupiter and Venus in the dawn sky.  These worlds seem to meet on the morning of May 11th, with Jupiter shinning at magnitude -1.9 about 0.5 degrees from -3.8 magnitude Venus. This will place both within the same field of view using a low power eyepiece, and may illicit queries of “what are those two stars low in the sky?” [Read more...]

AstroEvent: 4x Planets, 1xMoon, and a 12° FOV!

Where have all the planets gone? Four of the five classical naked eye planets are about to reveal themselves this week in a splendid fashion. As Venus sinks morning by morning towards the horizon, expect Jupiter, Mars and Mercury to emerge low in the dawn sky. The action culminates the weekend of April 30th-May 1st, when the waning crescent Moon approaches the grouping… use brilliant Venus as a visual “anchor” to guide your eyes to the fainter planets. On what date will you be able to spot each planet from your location?

[Read more...]

AstroEvent: A Close Planetary Pairing +A Springtime Meteor Shower.

Where have all the planets gone? Well, with the exception of Saturn, they’ve all been hiding in the direction of the Sun. That’s all beginning to change this week, however, as Mars, Mercury, and Jupiter slip into the dawn sky to join Venus in what will turn into a splendid early morning multi-planet conjunction in early May.

[Read more...]

03.04.11: Alien or Aeolian?

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...]

12.03.11: Attack (on the) Cyanobacteria?

This sunny weekend, we’d like to give some thought to the news story that erupted last weekend. Unless you’ve been off world, you’ve no doubt heard that researcher Richard B. Hoover of NASA’s/Marshall Space Flight Center released a paper via the Journal of Cosmology indicating the possible presence of fossilized cyanobacteria in certain types of carbonaceous meteorites.

[Read more...]

04.01.11:A Martian Eclipse.

I never get tired of catching a glimpse of the sky from other vantage points in the solar system… today, as residents of the Old World enjoy a partial solar eclipse on Earth, we thought we would direct your gaze to an eclipse from Mars.

[Read more...]

Review: The Martians by Kim Stanley Robinson.

Creating your very own universe is a tough endeavor in the realm of Sci-Fi. While other “serious” fiction writers have a readymade reality in place for them, science fiction writers must create a believable one from scratch. One of the modern best in the business is Kim Stanley Robinson. Recently, we had a chance to pick up his 1999 book The Martians, and it was worth the wait.

[Read more...]

Astro-Event: A Difficult Occultation.

This week, interesting planetary goings-on are afoot low in the western dusk skies, if you have the patience to observe them. On the evening of Monday, December 6th, visual athletes will want to try and spot an extremely thin crescent Moon occult a fading planet Mars.

[Read more...]

AstroEvent: The Return of the SEB?

Followers of this column know that Jupiter has appeared rather odd during this years’ 2010 apparition. Specifically, the Southern Equatorial Belt, or SEB, vanished for the first time in the 21st century. This is not a unique or singular occurrence, as it happened no less than 12 times in the 20th century. It’s not completely understood why this happens, and why only the SEB is prone to this disappearing act and never its twin Northern Equatorial Belt. Now, there’s evidence that the SEB may be returning.

[Read more...]

Astro event: A Close Planetary Conjunction.

The dusk planetary action continues this week with a close conjunction of the planets Mars and Venus. Our two nearest planetary neighbors in space have been playing a game of apparent cat and mouse in the dusk skies, approaching each other within two degrees of arc July 31st, receding, and then approaching again. Closest approach is around August 19th, when both planets are within 1° 45’ of each other as seen from our Earthly vantage point. This is one of the better planetary conjunctions of the year, and a good study in comparative planetary characteristics and orbital mechanics.

[Read more...]

Astro-Challenge: See Saturn’s Moons in 1 to 7 Order.

This week’s challenge may also give you a unique photographic opportunity. On the evening of July 31st (my birthday!) Saturn’s moons will be in 1 to 7 order. This will occur from 6:45 to 11:15 Universal Time, and favor viewers in Australia and the Far East. Later in the evening over North America, only speedy Mimas and Enceladus will be out of order… now is the time to brush up on and perhaps nab some of those hard to spot moons; in descending magnitude, difficulty, and order number (#)  they are:

[Read more...]

Review: Microsoft’s World Wide Telescope.

The market for astronomical online software has really exploded in the past few years, and amateur astronomers and educators have reaped the benefit. What was offered by many companies for prices sometimes over 100$ a pop now can be had for free. Programs such as HNSky, Stellarium, and Google Earth all offer Planetarium-style software that can be run right on your desktop. This week, we’ll look at Microsoft’s entry into the market with their World Wide Telescope (WWT).

One thing that initially struck me about the WWT was the ease for loading and use. Several larger astronomy programs have a knack for crashing or locking up mere mortal computers that many of us employ in the field. Released in early 2008, it runs pretty seamlessly for a Beta application. And this isn’t just a knock off of Google Earth; WWT gives you full access to a spectrum of surveys, from Hubble, WMAP to 2-MASS and more. The WWT promises unrestricted access to astrophysical data in an online community format. I’m particularly interested to see what users do with this access and the homemade tours they produce.

So, how useable is this software for in the field astronomy? Well, WWT does come with telescope controlling capability via the popular ASCOM series of controllers; in theory, one should be able to download the software plus the ASCOM drivers, connect and configure the telescope, and use it to point the instrument at various objects. Most new telescopes are now of the GOTO variety, although I’ve used similar software in a manual pointing capacity. I’ve heard of some users having difficulty getting the WWT to work in this regard…we welcome any personal success/failure stories as we have not yet attempted the use of WWT in this mode.

As a simulator, WWT does the job pretty well. For an example, we simulated next month’s South Pacific eclipse from various locales, and the WWT performed flawlessly. While use of the time controls and spatial location is pretty straight forward, we would like to see the inclusion of a local horizon and transit meridian to get a sense of our local bearings… an overall orientation does exist in the lower right side of the control panel but a plug-in addressing this would be handy, lest your telescope start pointing at the ground…

Which brings us to what I believe is the WWT’s greatest asset; its use for education. Star party clouded out? WWT would be a tremendous backup resource with its numerous tours of the sky; just keep in mind that it’s not a true “stand-alone” program as it does require an Internet connection to operate in the field. Right click on an object, and it gives you a quick look list of data. The format for star info is particularly refreshing… it gives you proper name, SAO, and just about any other pertinent catalog designation, all in one shot. This eliminates tedious cross referencing, as your scope may refer to a star by its esoteric forgotten medieval name (!) while you’re trying to hunt it down by SAO designator…

And heck, WWT is just plain fun to play with… I love the ability to probe the universe in infrared goggles, or pan around the Phoenix Lander site. Now in its second year, I’m really interested to see what folks will do with this new web-based tool and how new data will be integrated.  One could easily see amateur astronomers banding together to use the data to scout out new comets or asteroids, or creating historical, you-are-there tours of the cosmos, or perhaps simply sharing their latest images or favorites via the community. You can never have too many planetarium programs, and WWT makes a worthy and unique addition to any growing collection.