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History: Deep Space 1 June 30, 2009

Posted by gnhsphysics in Astronomy, Space Craft.
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EIU Astro is happy to have our first guest contributor for the summer, Paul Holder, whose blog is at: http://gnhsphysics.wordpress.com/

Deep Space 1 was launched from Cape Canaveral on October 24, 1998. During a highly successful primary mission the team tested twelve advanced high-risk technologies in space. In an extremely successful extended mission it encountered Comet Borrelly and returned the best images and other science data ever obtained from a comet. During its successful hyperextended mission, it conducted further technology tests. The spacecraft was retired on December 18, 2001.

Deep Space 1 was the first spacecraft to utilize ion engines. Ion engines use ejected ionized xenon gas instead of chemical propellants. Only a very small amount of xenon is ejected at a time. It may take four days or more just to use one kilogram of xenon. Becasue of this small ejection mass, the reaction force experienced by the spacecraft is also small. If you rest a piece of paper on your hand, the paper pushes on your hand about as hard as the ion engine pushes on the spacecraft.  The benifit of the xenon ion propulsion is that unlike chemical engines, which generally can only be operated for minutes, ion engines can be operated for years. Even though the force that acts on the craft is small, it is applied over a long period and produces a large impulse. The net effect of this is a large change in momentum (velocity), eventually attaining speeds far beyond the reach of chemical propellants.

Ion Propulsion System courtesy NASA

Deep Space 1, using less than 74 kg (163 pounds) of xenon, accelerated by about 4.3 kilometers/second (9600 miles/hour) over a period of 678 days. This is greater than any spacecraft has ever been able to change its speed and a longer duration than any previous propulsion system. This was attained while operating conservatively. DS1 could have achieved still higher velocity, but mission controllers had to fulfill defined mission objectives.

The team that developed and flew NASA’s Deep Space 1 spacecraft received the American Institute of Aeronautics and Astronautics’ prestigious Space Systems Award “For the outstanding performance of the team during design, implementation, test, operations, and extended mission including space flight test of 12 important, high-risk technologies.” The award was presented on April 2, 2003, during the Responsive Space Conference in Redondo Beach, Calif.

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Observatory Open House Tonight! June 26, 2009

Posted by jcconwell in Astronomy, IYA 2009, Observatory.
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The “Last Friday of the Month” open houses resume tonight at 9:00 PM, rain or shine! This month, if the cloud stay away we will try to see some of the wonders of our own galaxy the Milky Way, through the 16″ telescope. If it’s cloudy, come take a tour,  rotate the dome, and ask Dr Conwell some questions.

Observatory Welcomes Moraine Valley Upward Bound June 25, 2009

Posted by jcconwell in Astronomy, Observatory.
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IMG_1376

Click on picture for full size

EIU Observatory welcomes Moraine Valley Upward Bound Program. These brave souls walked a half mile from the road this afternoon  in 97 degree weather! Just to see us in the daytime! It’s a good thing I didn’t tell them it was 108 under the dome, and 124 before the dome was opened. All turned out well. Everyone got CDs of astrophotos and they didn’t even mind my bad jokes, and I didn’t mind the good questions.  I hope to Eastern sees some of them in the future as potential physics and astronomy students.

New Podcast at 365 days of Astronomy June 18, 2009

Posted by jcconwell in Astronomy, Podcast, Solar and Space weather.
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365_iyaToday’s podcast sponsered by the  EIU physics department is at :

http://365daysofastronomy.org/2009/06/18/june-18th-themisartemis/

THEMIS which stands for “Time History of Events and Macroscale Interactions during Substorms” is a constellation of 5 satellites and 30 ground-based observatories studying Earth’s magnetosphere and aurora. The main aim of these satellites was to answer fundamental questions concerning nature of an abrupt and explosive release of solar wind energy stored within the Earth’s magnetotail, known as a substorm. Having achieved most of its primary objectives of establishing when and where the substorms begin, the satellite mission will split up in July to become two missions. The first, THEMIS-Low, consisting of the three inner probes will continue to study the Earth’s space environment. The outer probes will explore the space environment of the Moon and renamed ARTEMIS: “Acceleration Reconnection Turbulence, and Electrodynamics of Moon Interaction with the Sun.” NASA has extended the THEMIS/ARTEMIS mission to the year 2012.

In this podcast we talk to Dr. Vassilis Angelopoulos, UC Berkeley, the PI of the mission, Dr. Manfred Bester, the THEMIS Mission Operations Manager and Dr. Laura Peticolas, the lead Education and Public Outreach scientist for this mission. We learn about the discoveries and insights learned from THEMIS, what we hope to learn from ARTEMIS and how these discoveries can be shared with the public.

Five New Supernovae Before Breakfast June 15, 2009

Posted by jcconwell in Astronomy, telescopes.
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In a preview if the new superautomated survey telescopes that are appearing in the next few years…this from Palomar observatory. The venerable 48″ Schmidt telescope, the largest in the world, that was responsible for the grandfather of all surveys , the original Palomar sky survey has been automatated and given a  new life as the  48-inch Samuel Oschin Telescope.

Edwin Hubble using the 48" Schmidt Telescope

Edwin Hubble using the 48" Schmidt Telescope

An innovative sky survey has begun returning images that will be used to detect unprecedented numbers of powerful cosmic explosions-called supernovae-in distant galaxies, and variable brightness stars in our own Milky Way. The survey also may soon reveal new classes of astronomical objects.

All of these discoveries will stem from the Palomar Transient Factory (PTF) survey, which combines, in a new way, the power of a wide-field telescope, a high-resolution camera, and high-performance networking and computing, with rapid follow-up by telescopes around the globe, to open windows of discovery for astronomers. The survey has already found 40 supernovae and is gearing up to switch to a robotic mode of operation that will allow objects to be discovered nightly without the need for human intervention.

The Palomar Transient Factory is a collaboration of scientists and engineers from institutions around the world, including the California Institute of Technology (Caltech); the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (LBNL); Columbia University; Las Cumbres Observatory; the Weizmann Institute of Science in Israel; and Oxford University.

During the PTF process, the automated wide-angle 48-inch Samuel Oschin Telescope at Caltech’s Palomar Observatory scans the skies using a 100-megapixel camera.

The flood of images, more than 100 gigabytes every night, is then beamed off of the mountain via the High Performance Wireless Research and Education Network¬-a high-speed microwave data connection to the Internet-and then to the LBNL’s National Energy Scientific Computing Center. There, computers analyze the data and compare it to images previously obtained at Palomar. More computers using a type of artificial intelligence software sift through the results to identify the most interesting “transient” sources-those that vary in brightness or position.

Within minutes of a candidate transient’s discovery, the system sends its coordinates and instructions for follow-up observations using the Palomar 60-inch telescope and other instruments.

Soon all of the steps in the process will be completely automated, including decisions about which transients merit a second look. When follow-up observations indicate that candidate transient detections show promise, a prioritized list of candidates is brought to the attention of astronomers from the PTF member institutions. Finally, an astronomer becomes personally involved, by performing detailed observations using telescopes such as Palomar’s 200-inch Hale Telescope, a Keck Telescope in Hawaii, or other partner telescopes around the world.

Upgraded 48" Oschin Telescope

Upgraded 48" Oschin Telescope

The PTF is designed to search for a wide variety of transient sources with characteristic timescales ranging from minutes to months, giving astronomers one of their deepest and most comprehensive explorations of the universe in the time domain.

“By looking at the sky in a new way, we are ushering in a new era of astronomical discovery,” says PTF principal investigator Shrinivas Kulkarni, MacArthur Professor of Astronomy and Planetary Science at Caltech and director of the Caltech Optical Observatories. “Nimble automated telescopes and impressive computing power make this possible.”

“No one has looked on these timescales with this sensitivity before. It’s entirely possible that we will find new astronomical objects never before seen by humans,” says Nicholas Law of Caltech, the project scientist for PTF.

Because it looks for anything changing in the sky, the PTF survey covers a vast variety of different astronomical targets. The wide range of the survey extends across the entire universe. Astronomers expect to discover everything from stars exploding millions of light-years away to near-Earth asteroids that could someday impact our planet.

Much of the survey’s time is spent searching for so-called Type Ia supernovae. These supernovae, formed from the explosion of a class of dead star known as a white dwarf, are very useful to astronomers because they can help determine the distance to galaxies located across the universe. Those distances allow astronomers to probe the origin, structure, and even the ultimate fate of the universe.

By operating more rapidly than previous surveys, PTF will also detect objects of a completely different nature, such as pulsating stars, different types of stellar explosions, and possibly planets around other stars.

PTF’s innovative survey techniques also have raised astronomers’ expectations of finding new, unexpected, astronomical objects.

The PTF already has found many new cosmic explosions, including 32 Type Ia supernovae, eight Type II supernovae, and four cataclysmic variable stars. Intriguingly, PTF also has found several objects with characteristics that do not exactly match any other objects that have been seen before. PTF astronomers are eagerly watching these objects to see how they change, and to determine what they might be.

The quantity and quality of incoming data have astonished astronomers working in the field. On one recent night, PTF patrolled a section of the sky about five times the size of the Big Dipper-and found 11 new objects. “Today I found five new supernovae before breakfast,” says Caltech’s Robert Quimby, a postdoctoral scholar and leader of the PTF software team. “In the previous survey I worked on, I found 30 in two years.”

Source: California Institute of Technology

Herschel telescope wakes up! June 14, 2009

Posted by jcconwell in Astronomy, telescopes.
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Hershel space  telescope opened its hatch that has protected its sensitive instruments from contamination, allowing  light collected by its  3.5m mirror to enter its supercold instrument chamber, or cryostat, for the first time The observatory’s quest is to study how stars and galaxies form, and how they evolve through cosmic time. The command sent on Sunday to fire two pyrotechnic bolts holding down the hatch was arguably the key moment in the European Space Agency (Esa) mission since the 14 May launch from Earth.

Herschel

For more information go to the BBC NEWS. Also see an earlier article form May’s Blog  here.

Oops! New podcast up at 365 Days of Astronomy! June 9, 2009

Posted by jcconwell in Astronomy, Podcast.
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Well, since I’ve been away visiting family and friends in Nebraska this last few weeks (twice!), I neglected to tell you about the new podcast that went up sponsored by the physics department.

http://365daysofastronomy.org/2009/06/02/june-2nd-sky-above-and-worlds-beyond-a-book-review-and-memoir/

While your there, check out the other wonderful podcasts, one a day. They are just perfect to listen to on a short commute, about 10 minutes. If you need a stronger longer dose, about 1/2 hour, you’ll not find any better than  go to our friends at  “Astronomy Cast”

Celebrating the first Anniversary of EIU Astro June 3, 2009

Posted by jcconwell in Astronomy.
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Today, June 3rd, marks the first anniversary of this blog and the 90th post. We have had over 18,000 visitor in the last year, and it keeps on going up. We are now having about 150 hits a day or 4500 a month.  Many thanks to those who have added comments, and may you all have clear skys.

What goes into making a picture? June 2, 2009

Posted by jcconwell in Astronomy, Observatory.
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Anyone who has ever seen the amazing pictures that are taken from the Hubble space telescope knows how beautiful the universe is. But those pretty pictures are like making sausage. The raw material may look ugly. To give you an example, let’s take a look at a picture taken by the students for the astronomical techniques course. Taken at EIU’s 16″ scope , the Whirlpool galaxy M51.

Raw 30 second picture direct from the telescope

Raw 30 second picture direct from the telescope (Click to enlarge)

If you click you see the grainy detail. Most of this grain is heat noise on the digital camera. You don’t see this in your home camera because your exposures are short. Over 30 second the noise  will build up. To get rid of this astronomers cool their cameras, for this camera, the SBIG-8, every 6 degrees Celsius I cool it, half the pixel noise goes away. This camera is cooled to 40 degrees below the outside. This image you see is a jpeg. The original file is in a format used by astronomers called FITS.  In that format and on my computer screen it’s even uglier, for some reason when it’s on wordpress it looks better.

Now I’m old enough that when I was 14 and using film,  I would have sold my soul (almost), for this good of a picture. And yes, my students, I do have a soul , I just lack a heart.

But we can do better.

One of the tricks you can do with a digital camera is subtract the heat noise. You do that by taking what is called a dark field…. a picture at the same temperature for the same time 30 seconds, with the shutter closed. This is a picture of the heat noise.  Then you subtract that picture from the real one canceling (almost ) the heat noise. There are other things you can also do to correct for dust on your optics, take a picture of a blank white wall, which are called flat fields, and divide that out. But the main problem is not enough photons.

Now to get more photons you either get a bigger scope or a longer exposure. But with digital cameras you can also add many short  exposures to make a long exposure. That what we did here. By taking ten 30 second exposures and cleaning them up using our darks and flats we get:

ten exposure added together

ten exposure added together

Now in the interest of truth in advertising, there is on more enhancement that was done here. If you look at the first, raw, photo you’ll see that the center of the galaxy looks brighter. Onr problem is looking at astro-photos is you’d like to see the details in both the bright and dark regions, but the computer and eye can only handle about 256 shades of grey. If you look at dim regions in thspiral arms, the  center get burnt out and looses detail. If you dim the image to see the center the spiral arms become too dim.  But between computers and digital images we can enhance the image, to see both. That’s what was done here. We told the computer to assign more of the 256 shades of grey to the dimmer sections and less shades to the very black space  and very white center, bringing out the detail of both. But to make a picture pretty you may loose some information, like the relative brightness, so you have warn people, that may use it for scintific work, when an image is enhanced like that.