September 2012 Sky from the Keeble Observatory
Now that we know of Curiosity’s spectacularly successful landing on Mars, I can write about the rover without seeming to “jinx” it.
However, I would be remiss if I let the passing of Neil Armstrong at the age of 82 go unmentioned. As a child of the 60s and an avid fan of the space program, I followed with great zeal everything NASA, and could at one time name the flight crews for every Mercury, Gemini, and Apollo mission. Neil Armstrong was flying fighter jets when I was born. He was part of the second class of pilots named as astronauts (the first class were the so-called Mercury 7), and had an uncanny skill as a pilot to recover from potentially deadly situations. On Gemini 8, he was the first to dock with another spacecraft. When one of the thrusters stuck and sent the combined craft into a violent spin that nearly made Armstrong and Dave Scott black out, he managed to regain control and save their lives. He ejected at the last possible instant from an out of control training rocket as he prepared for the historic first Moon landing. And in the summer after I graduated from high school, he had only 9 seconds of fuel left when he safely maneuvered the Apollo 11 lander away from a boulder field and set it down on the dusty Sea of Tranquility on July 20, 1969. Always quiet and unassuming, he credited the entire NASA team with his success, and then retired to teach near his boyhood home in Ohio. God speed, Neil Armstrong (August 5, 1930 – August 25, 2012).
Back to Mars – Curiosity successfully touched down on the Martian surface in Gale Crater on August 5th. The rover’s mass is just under a ton, which makes it the heaviest probe ever to land on Mars. It was too heavy to land via airbags, so a complex rocket powered “sky crane” lowered it gently and safely to conclude the so-called “seven minutes of terror” as it plunged into the Martian atmosphere at 13,000 miles per hour. Congratulations to the engineering team that designed, built, and programmed the flight hardware and software to pull this off. For comparison, it is about twice as long (about 10 feet) and five times the mass of the earlier Spirit and Opportunity rovers launched in 2003.
Unlike previous surface probes, this one is not powered by solar arrays. Rather, it has a Radioactive Thermal Generator (RTG) which relies on the decay of an isotope of plutonium to generate power. This rover will not have to sit out the long Martian winters, or worry about dust on the solar arrays degrading its ability to perform its tasks. The instrumentation includes a weather station (our first on Mars since the 1976 Viking landers), high definition cameras, and the most sophisticated array of science instruments yet deployed there. It’s six wheel drive system can climb over obstacles up to 25 inches and should carry it up to 200 meters (660 feet) a day.
Instruments include a gas chromatograph, a mass spectrometer, and a tunable laser spectrometer. It will be able to take detailed close up images of rock and soil, able to refine details smaller than the width of a human hair. High definition stereo cameras will allow study of the overall terrain as Curiosity climbs 5.5 km high Mount Sharp in the center of the 96 mile wide crater. (Mount Sharp is an informal name – its official IAU designation is Aeolus Mons.) Orbital images reveal layered sediments, whose study may reveal up to 3 billion years of geological history (or areological history!). The prime mission is to look for evidence of organic (carbon bearing) compounds, which would help answer the question of whether life as we know it could ever have evolved on Mars. We already know there was once abundant liquid water on a younger, warmer Mars.
An instrument which simply sounds like fun is known as the ChemCam, which will use a 50 megawatt pulsed laser to vaporize and ionize surface layers of rock and soil, and then analyze the spectra emitted by the plasma produced. Initial tests were impressive, as researchers claim that it gives better data on Mars than when it was tested on Earth.
The mission timeline calls for a full Martian year of study, which is 687 Earth days. The mission can be extended as long as the RTG continues to generate sufficient power. Considering that the half-life of plutonium-238 is 88 years, expect many years of exciting science to come! You can follow the Curiosity mission and see the most recent results and images at http://www.nasa.gov/mission_pages/msl/index.html.
Lunar phases for September: Last Quarter on the 8th, at 9:15 am; New Moon on the 15th, at 10:11 pm; First Quarter on the 22nd, at 3:41 pm; Full Moon on the 29th, at 11:19 pm.
If you’re up in the hours before sunrise, you’ll find Venus and Jupiter very bright above the eastern horizon. Venus is the brighter of the two, about 30 degrees above the horizon, near Castor and Pollux in Gemini. Jupiter is around 65 degrees above the horizon, roughly east-southeast. As we go through September, Jupiter will move higher until it lies due south by month’s end. Venus settles closer to the horizon, remaining essentially due east at sunrise near the end of the month.
Evening planet watchers will have less luck, as Mars and Saturn begin the month low to the southwest after sunset and the onset of twilight. They move closer to the Sun’s position, and hence lower at sunset as the weeks pass. As we approach October, Saturn will be setting within an hour of sunset, and Mars follows not far behind. The ecliptic makes a shallow angle with the horizon here, so both are likely to be lost in haze and horizon clutter. Mercury returns by the end of September, but is even lower than Saturn.
Our mid-month view of the sky, about two hours after sunset, finds Cygnus (the Swan) at zenith, appearing to glide along the Milky Way from northeast to southwest. The bright star Deneb marks the tail of the swan, about ten degrees northeast of zenith, and the head is at Albireo – a beautiful binary system. At a similar angle to the west we see brilliant Vega in the constellation Lyra. These two bright stars make a triangle with Altair, about 30 degrees south of zenith. With binoculars, on a clear dark night, just east of Deneb you may find the ghostly, familiar outline of the “North America Nebula. Cassiopeia is to the northeast, looking like a W tipped backwards. If you follow the line of the “left” side of the W toward the east you’ll notice the faint fuzzy patch of the Andromeda Galaxy, about 45 degrees above the eastern horizon. It’s best seen on a clear, moonless night, and best by “averted vision” without binoculars. That you can see it at all gives some sense of the scale of our Universe, since this is the most distant object visible to the naked eye. It’s practically in our back yard! This spiral galaxy is only 2.2 million light years away, and is on a collision course toward our home Galaxy … though we have about 5 billion years to get ready. It was Edwin Hubble who first resolved the Andromeda Galaxy into individual stars and made a first calculation of its distance. He got the number wrong, but at least was able to show that it was not a nearby cloud, but a system of hundreds of billions of stars, much like our own Milky Way.
Copyright 2012George Spagna