What Voyager is doing now

In our last article about Voyager, we discussed Voyager's last photo from space. After taking that photo which was the end of the grand tour, it seemed reasonable to shut down the mission and let the spaceships continue their eternal journey in space. However, since the spaceships' condition was still very good, most of the systems still functioning and their location was the furthest any object had arrived it seemed sensible to find a new mission for Voyager and not let it waste in space.
Every end is a new beginning and the end of the "Grand Tour" was the beginning of VIM - "Voyager Interstellar Mission". You might have heard on the news that Voyager left or is about to leave the solar system. This is not accurate and we need to first determine where the solar system ends. If our criteria for the edge of the solar system is the distance at which the sun gravity has little effect on celestial bodies, Voyager is still in the inner part of the solar system. The influence of the sun gravity reaches to a distance of about 1 light year from the sun, to the end of the Oort cloud.
A definition which is better for our purpose, is the border of the magnetic field of the sun. The sun's magnetic field moves with the sun. As it is illustrated in the diagram below, the magnetic field seems like a bullet advancing with the sun. It travels with and in front of the sun and stretches to a great distance behind it. Charged particles from the sun (a.k.a "Solar wind") travel very fast, they start to slow down when they meet other charged particles coming from space (a.k.a "Space wind"). The area where Voyager 1 is currently traveling is the place where these two "winds" meet ("wind" is used as a metaphor).

Voyager Interstellar Mission. NASA

In this diagram, the inner circle is the Solar system with its 8 planets (as we said before, there are other objects further away which orbit the sun). The Heliosphere, the sun's atmosphere, reaches beyond and behind the sun, and the Heliosheath is the area where Voyager 1 is currently traveling.
The size of the Heliosheath is unknown and it is changing constantly. The scientists hope that Voyager will be able to cross it and reach the area of the bow-shock. Voyager's energy supply (we will deal with this matter in our next article) will last for the next 10-15 years. In order to conserve energy, all unnecessary instruments were shutdown long ago, and only 5 systems are still functioning. These systems include the communication system, the magnetometer and other instruments to measure the speed and direction of charged particles.
What Voyager discovered is that particles from the sun's direction become slower and slower, and particles not from the sun's direction become more and more common (and with greater speed). This means that Voyager is getting nearer to the area where the majority of particles will not be from the sun (and only in that sense, leaving the solar system). So, it is now a race against time, to get as far as possible before all Voyager's energy is used. The current distance of Voyager 1 from the sun is 120 AU (astronomical unit - the distance from the sun to earth - 150,000,000 KM) and its speed is 3.6 AU per year. In 10 years it will reach a distance of 150 AU from the sun, and if it will still function we will learn a lot about the strange conditions at that far place. Voyager 1 is the front lab of humanity and it provides sci-fi enthusiastic some food for thought  about spaceship travels to other stars and planets.

See Voyager exact distance from earth and sun

Previous articles
Voyager - The grand tour
Voyager's last photo

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. 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"

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

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.

AstroBlogger write to us about several things you need to do before announcing you have discovered Nibiru/ planet X or any other unknown object in the sky.

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.

Voyager - The Grand Tour

Voyager spaceships deserve their names. They travel in space farther away than any other object and will continue to do so for many more years. Celebrating 35 years for the Voyager launch, we will dedicate several articles which will present various aspects of this great mission, the longest ongoing active mission that NASA holds.
Note: Although there are two Voyager spacecrafts we will mostly use the singular form, unless necessary to differentiate between the two spaceships.

When the Voyager mission was first planned there were so many question marks about the solar system. Our knowledge was just a fraction of the knowledge we have today. Many details about the gas giants, especially Uranus and Neptune were totally unknown and spaceships only traveled to our near neighbors: the moon, Venus and Mars.

The first problem for space traveling is the great distances between the destinations, and the fact that there is a need to get there in a reasonable time, otherwise the spaceship itself might not work properly. Sending something directly to the edge of the solar system was not possible and required extremely large rockets and quantities of fuel. That was until someone (and there is some disagreement about who exactly is that someone, so I will not write any names) thought of a marvelous idea. There was no need to go directly to Neptune. It was enough to reach Jupiter at the correct time and angle. The massive gravity of Jupiter would accelerate the spaceship even more, and throw it outward toward Saturn. It was possible to do the same at Saturn, throwing the spaceship to Uranus and again to reach Neptune, in a reasonable time of about 10 years only (and not 25) which was less than the spaceship's expected life time. The term for such a maneuver is Gravity Assistance or the Slingshot Effect. This conclusion was reached in 1965.
The calculations of the such trajectories are extremely complicated, as the spaceship must be at the right distance from the planet, at the right angle and at  the right speed, otherwise it might crash on it or go into orbit around it. The Voyager itself had an engine and some fuel but this engine was used for minor trajectory corrections (or to give just a bit more of acceleration). The calculations required many computer hours (the computers at that time were much less powerful than today), but eventually such calculations were finished (by hand or with computers) and they showed that all planets would be aligned for such a tour in the late seventies!
However there were many political issues as well. In the early 70', the Apollo program was coming to an end, NASA started to work on the Space Shuttle programs and the planetary science was neglected a little. However, JPL started to present the idea of the "Grand Tour" to the end of the solar system, not just to near planets, with much better equipment than the Pioneer spaceships. Finally the green light was given.
Since so many details about Jupiter and Saturn were unknown it was impossible to set exact trajectories until more data was gathered, however it was impossible to wait for a spaceship to gather that data as the correct alignment of planets would pass. Therefore, two almost identical Voyager were sent. The first one, Voyager I's goal aim was to go to Jupiter and from there to Saturn only, providing many details which were required for a finer calculation which were used by Voyager II some months later to manage to travel the exact route to Uranus and Neptune.
Due to some technical reasons the first launch was that of Voyager II in August 20th 1977, and Voyager I just two weeks later on September 5th. Voyager I's speed was slightly higher and it quickly passed Voyager II, thus starting the longest journey ever.

Voyager