Tuesday, May 27, 2014

DSN celebrates fifty!

It really doesn't matter how good your spaceship is, where it is going or which great photos it took, if that information will not reach back to Earth, the entire effort will be in vain.
One of the greatest things that NASA did, if not the biggest wonder, is the Deep Space Network (DSN) which celebrates its fiftieth birthday.
The DSN is a marvelous engineering piece of work supporting spacecrafts as old as fifty with all different kinds of communications methods, bandwidths and protocols. The network supports  mission of close and extremely far from earth up to 19 Billion kilometers, as well as connecting with other networks which supports Low earth orbits satellites.
The network is the heart of all NASA's operations and one of the most critical assets of the planetary research.

The network has three bases spread over the entire globe. One center is in California, the second is in Spain and the third is in Australia. In those centers there are many dishes. The biggest ones are 70m in diameter and are used to receive the weak signals from Voyager 1 missions. It takes 18 hours to the signal to reach Earth. The download speed is awfully low, just 120 bits (yes bits, not Mbits) per second. In the beginning of Voyager mission and when it was closer to Earth the speed was much higher but the far distance and the need to conserve energy slowed it down.

אנטנת 70 מטר, גולדסטון קליפורניה
The 70 meter dish at Goldston California
But Voyager is not the only mission in the solar system. There are dozens of other missions and all need their communication time-slots. Each mission has different protocol, bands, frequencies and the antennas must be pointed very accurately. Managing the operation is a 24 hours job and not an easy one.
The network starts to work from a distance of 15000km from Earth. A spacecraft in this distance will always "see" at least one of the network's bases. The ISS and other satellites use different network system.
The antenna are always working and although they need maintenance there is currently no plan to do it. Such activities will bring down its networking abilities for long time and will prevent the normal operations of the missions. Keeping the DSN up and running is a major challenge for NASA in the coming years.

To celebrate the 50th birthday of the networks, NASA created a site -DSN Now- which will show you which antenna is "speaking" with which spaceship. I got addicted.

NASA's DSN site

Monday, May 12, 2014

Carnival of Space #353

Welcome to a new edition of COS, number #353, with many articles by our community. A great list of articles dealing with astronauts, stars, planets, moon, comets, asteroids, spaceship, space's history rockets and space's business. There is no way that you will not find good material reading here.

Astroswanny investigates approaching Asteroid 2014 HQ124 discovered two weeks ago by the NEOWISE survey. Currently visible to only southern telescopes in the pre-dawn sky, 2014 HQ124 will make a 3.2 Lunar Distance close approach on June 8th. This is quite close for a large newly discovered asteroid whose size is between 300-500m.

Urban Astronomer takes us to  Titan - the largest moon of Saturn, which is an enigmatic little world. It has earth-like weather, rivers and seas, yet has an average temperature more than a hundred degrees below the coldest weather ever measured on Earth. The more planetary scientists learn about it, the more questions come to light.

Two articles from Universe Today:
  •  Are we ready for contact - Nero-psychologist Gabriel G. de la Torre from the University of Cádiz is questioning whether or not astronomers, who have previously only looked for signs of extraterrestrial life, should actively send messages from Earth.
  • While no one’s yet invented a replicator that can brew a cup of tea out of thin air, scientists have taken in step in that direction by creating an amazing replica of a Martian meteorite using a 3D printer .
 Chandra also sends us two stories
 And the two items of CosmoQuest
  • Planets in the sky (All naked eye are visible) - Go out and look up! Enjoy the planetary offerings in the night sky right now as the weather gets nicer. 
  •  On the Educators' Zone, we're collecting ideas for crafty and artsy space and science projects. Have some in mind, please share! And visit our new collaborative Pinterest board to browse more ideas. 
 Don't miss Space-io9 a recently new member of CoS! Welcome!
From the Meridian Journal desk
NextBigFuture with latest breaking news
  •  The Spacex Falcon 9R rocket rose to a height of 3280 feet (1000 meters) in its latest test, posted on May 1st, 2014. The legs were in a fixed down position from launch to landing, but future tests will begin with them stowed.
  •  Planetary Resources has shifted the company's focus to a more mundane space resource: water. Water found on or near asteroids, their theory goes, could be processed into fuel to extend the useful lives of aging commercial satellites.
  •  Planetary Resources co-founders discuss the space mining companies plans and progress

That's all for this week, enjoy and don't forget to browse a bit in my own site .

Tuesday, May 6, 2014

How to photograph stars and constellations

This article will focus on tips and techniques to photograph stars and constellations using a regular camera and tripod. No telescope is required and even a simple camera will be sufficient.

The first difficulty that a photographer encounters is familiarizing himself with the night skies. It is better to begin with photographing well known constellations such as the big dipper, Orion and also to use free software such as "Stellarium" or "Google sky map" to become more familiar with the skies.

Photographing constellations is not a hard task. A telescope is not required and even a long zoom is not required since the constellations are wide. However a tripod is a must to perform long exposures. Here are some tips and techniques for constellations photography:
  • A tripod is a must have. If you are using a small camera even a small tripod will do, but you can't photograph stars without it
  • Photograph from the darkest place that is available to you. Many cities suffer from light pollution which will make the constellation background bright or even white
  • Usually you will not see the entire constellations with your eyes or on the small LCD screen of the camera but just the brightest stars. Use a wide focal length (no zoom) to include everything in the photo and crop later if necessary. Also you can take some test shots until you create the proper composition. For the test shot raise the ISO to 3200/6400. You don't care about noise and it will save lots of time.
  • Perform many tests and check the photos on a computer or laptop screen. It is impossible to see the photos properly on the camera LCD screen.
  • If possible, add some terrestrial landscape to the photo. Trees, mountains and building will give an extra touch to the photo. However take into account that light pollution is more severe in the lower part of the sky, so you will need to compromise.
  • The earth is rotating around its axis and in a long exposure the stars will create trails. Use bigger aperture (Lower F number) and raise the ISO definition to decrease the exposure time. If you like star trails, go ahead and photograph them. Too high ISO value will create more noise in the photo so don't raise it too much, usually 400 is a good value.
  • As a rule of thumb divide 500 by the focal length of the lens to estimate the longer possible exposure before the stars will make small trails.
  • Use manual focus and focus on a bright star that you see, even in a different constellation and even in a larger focal length (zoom). If you can't find a star use infinity.
  • Some people like to add tiny thin lines to the final photos. These lines will emphasize the constellations familiar shape. I do not like to add these lines as you will see in the examples below, but it is a matter of personal taste.
  • To prevent shakes from the cameras either use a remote control or shutter release. If you do not have these tools, just add a short delay 2-10 seconds to the photo. This feature is available on all cameras and is mostly used for selfies.
  • Use the Noise-Reduction feature in your camera. Usually it is turned on by default for long exposure. Using NR will take longer so there are times you can take a single dark photo (long exposure with the lens cap on) and do the NR in software later, but for most amateur it will be best to do it upfront immediately and automatically.
Another problem is uploading the photos to the Internet, since many sites compress them during the upload process. These kind of photos, with lots of black areas and just few white dots, are not compressed very well. If you have your own website, you can upload the photos to there, otherwise a service like imgur can provide a reasonable solution. Also PNG format will give better results from the JPEG format for sites like Facebook.

And now for several examples, all taken with an old  Sony Alpha 100 DSLR with 28-105mm lens, usually at the wide side. You will need to click the photos to see a larger image.

The first photo is the well known constellation - Canis Major - the great dog. Notice the difference between the black at the top of the photo and the brown at the bottom, due to the light pollution. Also a high ISO value was used and the photo has a lot of noise.

Canis Major - Great Dog
Canis Major - Great Dog
Perseus constellation
Perseus constellation
Here is the famous group Orion, Usually known for the trapezoid but includes many more stars above and to the right.
The entire Orion constellation
The entire Orion constellation
Sometime it is better to focus on part of the constellation. The following example shows the Pleiades (M45) and the Hyades in Taurus (The Bull). The brightest star is Aldebaran.
Pleiades (M45) and the Hyades in Taurus (The Bull)
Pleiades (M45) and the Hyades in Taurus (The Bull)

For a more advanced photographer, the skies are the limit (just as usual). Here are some more ideas which require time and investment just to give you a taste of the possibilities.
  • A tracking device will enable longer exposure without smudging the stars. A very affordable tracking device is the iOptron SkyTracker.You simply aim it at the north star and connect the camera to it. Such a device will enable long exposure as long as your camera supports.
  • There are special blocking filters which can somewhat improve light pollution, but do not expect miracles, go to a darker place.
  • Larger zoom lens can be used to photograph smaller objects. Such objects will be detailed in a separate article but as a taste here are the Pleiades taken with a simple Canon SX50 camera in just 1 sec of exposure. The mini dipper shape (which can be seen with the naked eye) is visible with dozens of additional stars.
הפלאידות - צביר בקבוצת שור, מכונה גם M45
M45 - Pleiades

Thursday, May 1, 2014

New moon timelapse

Sometimes seeing the new moon is not that hard. When the moon is far enough from the sun (30hours old), It stays long in the sky after sunset. Seeing the moon at or even before sunset is still hard, but twenty minutes later it will be very easy to spot it.
So was the new moon of April 30th 2014. I first saw it from Israel at 19:18 just a little before local sunset, and I immediately took photos. It was hard to focus since the moon was very faint. The difference between proper focus and improper are noticeable. Also if you search for the new moon with a binoculars, the focus is critical otherwise the thin crescent will not be seen

Out of focus new moon
Out of focus new moon

New moon in focus
New moon in focus
Even in a new moon, you can notice the red moon phenomena, but not as easy as with a full moon. The reasons are the same but since the moon is so thin, it will not be possible to see it in the eye at all some minutes before moonset. However a long exposure with the camera caught that photo at 20:30 just seconds before the moon disappeared behind the buildings (moonset was at 20:36)
ירח חדש בשקיעה
ירח חדש בשקיעה
I also photographed many photos to create a time-lapse of 1 hour in just 30 seconds. The interval between photos is about 20seconds. Watch on full screen with HD quality and enjoy.