Friday, September 14, 2012

Voyager - The Last Photo

Most people like family photos, and the more participants the merrier. But there is one family that it is particularly hard to photograph together, mainly because the distances between the brothers and sisters of this family can be above 5 billion KM and they will never get any closer. An experienced photographer will distance himself as far as possible and try to get just the right angle to include as many members of the family as possible. The family we are discussing is the solar system with the Sun and the planets. When Voyager finished the grand tour, it was in a great position to catch most of the family members in one photo. The spaceships' cameras were not needed anymore, both spaceships were not expected to observe additional celestial objects, and the decision was to take one last photo before shutting the cameras down forever. You remember that there were two Voyager spaceships, and to take that special photo, Voyager 1 was chosen, simply because it had a better viewing point. Voyager 1 left the ecliptic plane and was high above it, providing a better photography angle than Voyager 2 who was still near the ecliptic.
There were some other obstacles. The sun (the old grandmother of the family) is extremely bright. The planets (brothers and sisters) are dim and far apart from each other, and the moons (grandchildren) are just too small and dim, so the family portrait  is not really a single picture but a mosaic of about 60 photos combined together, taken with different exposure times and filter. The last of the Voyager mosaic is shown below, taken on February 14th 1990.
Voyager I portrait of the solar system.
Voyager I portrait of the solar system. Credit: NASA
OK, I am sure you did not exactly expect this as a family portrait but it is the best possible composition. The grey squares are the individual pictures, as mentioned, more than 60 frames were needed to get all members of the family, but as often happens, someone is still missing. The letters designate the planets (J - Jupiter , E - Earth, V - Venus , S - Saturn, U - Uranus, N - Neptune) and the bright dot is the sun.  Mercury and Mars are missing from the portrait. Mercury was too close to the sun, and Mars could not be found. Pluto which in 1990 was closer to the sun than Neptune and still a distinguished member of the solar system (until it was kicked out to be a dwarf planet) was too dim and was not included in this picture, maybe as a prophecy to its destiny 15 years later.
The picture is in a very high resolution so please click on it to enlarge it. You will see excerpts presenting the planets themselves. It is possible to see some details on Jupiter and a hint of Saturn's rings. Uranus and Neptune seem larger but this is because the long exposure time of 15 seconds which gave them a little smudge. The sunlight is visible in many pictures, and the camera hardly managed to capture planet Earth. The size of our little planet is less than one pixel and the photograph that shows it got its iconic name by no other than Carl Sagan: "The pale blue dot"

Pale Blue Dot
The pale blue dot. Credit: NASA

After these photos, the Voyagers' cameras were shut down forever. Cameras need power, and power is a rare resource in a little spaceship, but these photos are part of the heritage that Voyager left us.

Previous Articles in the Voyager's series:
Voyager - The Grand Tour

Monday, September 10, 2012

Carnival of space #266

Hi and welcome to a new issue of "Carnival of space" your weekly gateway to astronomy and space articles and news.

Cheap Astronomy delivers a fine podcast on the Fine Structure Constant, described by Richard Feynman as 'the greatest damn mystery in physics'. 

Nextbigfuture send us 3 articles the first one is dealing with NASA is funding development into aneutronic nuclear fusion for space propulsion.
The second item from Nextbigfuture is about the lunar space elevator kickstarter which has raised over $70000 and still had one week to go. By the weekend it will still have a few days left and should be over $80,000 and the way to passing the $100,000 level. At the $100,000 - back in business for real, have a series of experiements and $250,000 - try for to climb to the limit of balloon technology , about 20 miles / 30 kilometers.
The last from Nextbigfuture is about NASA NIAC phase 1 project Water Walls (WW). Water walls takes an approach to providing a life support system that is biologically and chemically passive, using mechanical systems only for plumbing to pump fluids such as gray water from the source to the point of processing. The core processing technology of Water Walls is FORWARD OSMOSIS (FO). Each cell of the WW system consists of a polyethylene bag or tank with one or more FO membranes to provide the chemical processing of waste. WW provides four principal functions of processing cells in four different types plus the common function of radiation shielding.

As school year is starting in many places around the globe, the post-Labor Day week got us thinking about school and education as it relates to Chandra and X-ray astrophysics.

Weirdwarp has an article about Voyager 1 which has travelled the furthest any -made object has travelled in a straight line (well almost a straight line). We will probably and hopefully overtake it one day with future space technology but today it can bask in glory.
Voyager Model.
Most of Mars interest is focused on Curiosity, but there are other rovers doing great job on our red neighbor. The Meridian Journal tells us about Opportunity rover is examining an interesting rock outcrop which may contain some of the long-sought clay deposits.

Peter Lake takes a look at the newly discovered 375m Asteroid that will pass at about 7.4 lunar distances on the 14th. It is a little unusual these days to find such a big asteroid less than three weeks before its closest approach.

The second episode of The Cosmic Ray Show will air on September 11th, 2012 at 10:00 PM Pacific!
Our special guest for our second episode is Dr. Alan Stern, principal investigator for the New Horizons mission to Pluto. In addition to his scientific duties, Dr. Stern is also a founder of a new start-up, Uwingu. Uwingu aims to help fund space education, exploration and research.

This is all for this week, may your days be long and your nights clear. The next new moon will designate the newly Hebrew year (5773), best regards and happy new year "Shana Tova" to all of you.