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Voyager

Once in a lifetime

During the late 1960s, a NASA aerospace engineer called Gary Flandro identified a very special alignment of planets that would allow an earth-launched spacecraft to use planetary gravitational effects to travel to Jupiter, Saturn, Uranus, Neptune, and Pluto in a “Grand Tour”. This had never been done before and would not be possible again for another 175 years. By 1972, a project had been formed to build two craft ready for the required 1977 launch. Originally part of the Mariner program, they were first called Mariner 11 and Mariner 12 but soon renamed as Voyager 1 and Voyager 2. The two craft would take different routes through the solar system. Voyager 2 would, perhaps strangely, be launched first and would visit Jupiter, Saturn, Uranus, and Neptune. Voyager 1 would be sent on a shorter and faster trajectory designed to enable it to visit Jupiter and Saturn and, critically, provide a flyby of Saturn's moon Titan, which was thought to be the only other body in the solar system to have clear evidence of stable bodies of surface liquid. On the 20th August 1977, Voyager 2 launched and set off towards Jupiter. Less than three weeks later, Voyager 1 launched, it too heading for Jupiter where it would arrive slightly ahead of its twin. The mission was due to last just five years.

Jupiter.

Less than two years after launch, the Voyagers encounter Jupiter.

As they examined Jupiter, the Voyager craft would, between them, discover the first active volcanoes known to man beyond Earth (on the Jovian moon Io), lightning on Jupiter (again the first seen outside Earth), a ring system around the planet, and two previously unknown moons (Thebe and Metis). The “Great Red Spot”, that had been seen previously, was identified as a giant cyclonic storm system that at one time was 40,000 kms across (roughly three times the diameter of Earth). Ganymede was shown to have a grooved surface suggesting tectonic movement in its past. Io was also shown to have an unusual effect on the magnetic field of Jupiter which creates a “doughnut” of ions that increases Jupiter’s magnetic field.

Saturn.

Between late 1980 and late 1981, the two craft visited Saturn. Whilst here, they found three new moons and an Earth-like nitrogen rich atmosphere on Titan, took detailed photographs of the ring system and discovered a strange hexagonal weather feature on Saturn that circulates around the north pole of the planet. From here, Voyager 1 sets off on a path that will not encounter other planets but instead will head towards the edge of our solar system. Voyager 2, by contrast, heads for Uranus.

Uranus.

Early in 1986, Voyager 2 made its closest pass to Uranus, the first time this planet had been seen “close up”. Discoveries on this pass include 11 new moons, incredible photographs of new moon Miranda showing historic heating and cooling probably caused by proximity to other moons, identification of a “tilt” in Uranus’s magnetic field, temperatures as low as 59 Kelvin (minus 353 degrees Celsius).

Neptune.

Three years later, in 1989, Voyager 2 gets up close and personal with Neptune. Discoveries here include six new moons, the first images of Neptune’s rings, a huge storm that, unusually, rotates counter-clockwise, and close-up views of Neptune’s bitterly cold, fractured moon Triton. From here, Voyager 2 would begin its trip towards the edge of our solar system and leave the plane of the planets.

Interstellar Space.

Fast forward to 2012 and Voyager 1 becomes the first man-made object to enter interstellar space, beyond the regular influence of our sun. It is not until 2018 that Voyager 2 makes the same leap from the influence of the sun.

Gold Record.

Each Voyager craft carries a 30 cm gold phonograph record containing pictures and sounds from Earth (as it

was in the mid 1970s), directions in symbol form explaining how to “use” the record and data showing the location of Earth. Astronomer Carl Sagan chaired the committee that selected the content of the record. During the selection process, Sagan is rumoured to have rejected the idea of including some music by J S Bach as this would be “showing off”. Whilst widely quoted, this is considered unlikely to be true if for no other reason than the 1st track on the golden record is the First Movement of the Brandenburg Concerto No. 2 in F by … J S Bach.

Pale Blue Dot.

Sagan had requested that, just before Voyager 1’s cameras were switched off (to save power for other instruments), the camera be turned toward Earth and a final photograph taken. This image is known as the “Pale Blue Dot”. In it, Earth is more than six billion miles away and less than size of a single pixel in the picture but appears as a, not surprisingly, pale blue dot roughly halfway up the rightmost band of light.

The Voyagers in the Movies.

The Voyager craft have made several appearances in film and television. Most famously, perhaps, in Star Trek: The Motion Picture where a machine called V'Ger – which turns out to be the (fictional) Voyager 6 spacecraft, its intelligence greatly enhanced by an alien race - seeks the home of its creator, Earth, and threatens to wreak havoc on our planet in the process.

Voyager has also appeared in The West Wing (it featured as a major mission milestone where Voyager crossed the Termination Shock and one of the characters announced to the press that it had “left the solar system” – when it had not).

The X Files included references to the Voyager programme in several episodes and in a 1978 episode of the American TV programme Saturday Night Live, a psychic (played by Steve Martin) claims that aliens have found the golden record and contacted him with a message. The message is “Send more Chuck Berry”.

Neptune

The Numbers.

There are so many incredible numbers that I could put here but here are just a few that really stand out to me. • 1970s. The technology on-board the Voyager aircraft is what was available in about 1973. I had JUST brought my first desktop calculator (which was immediately confiscated by my maths teacher) – NASA at the same time built two spacecraft that have done so much amazing work. • 45 years. Originally designed for a “five year mission” (sound familiar?) both Voyagers are still going 45 years later. They have been remotely reprogrammed several times and power is now critically low … but they are STILL going. My last mobile phone packed up after two. • 14 billion. The number of miles that Voyager 1 is from the sun (as I write this). Voyager 2 is "only" 12 billion miles away.

• 60,841. The speed (in kmh) at which Voyager 1 is travelling. Voyager 2 is slightly slower (but only slightly).

And Finally …

There has been, over the years, much discussion (not least on that episode of The West Wing) about how, if or when the Voyagers will “leave the solar system”. The edge of our solar system, that is “the cosmographic boundary of the Solar System and the extent of the Sun's Hill sphere”, is thought to be the outer edge of the “Oort Cloud”. The Voyagers will not ENTER the Oort cloud for another 300 years and will not exit it for another 30,000 years. My bet is that they will still be working.

Voyager 1 Launches Aboard Titan III

Taking Better Photographs ...

Focus

by Steve Marshall

The best pictures have a sharp focus so the viewer can see exactly what is in the image.

Sharp focus needs a steady camera, so always hold the camera with both hands. This is especially important if you are using a screen. An eyepiece helps to hold the camera against you. Lean on a post or a wall or anything else that will help you stay stationary. Use a tripod or place your camera on a surface such as a gate or table. The longer your shutter speed, the more important this becomes.

Where to focus

Most cameras and mobiles default to what is called area or matrix focus. This means they will try and focus everything from front to back – giving an average focus – which may not be what you want.

I recommend setting your camera to point focus – so that point in the photograph will be in the sharpest possible focus. You may need the manual to set this - paper or electronic.

You can do almost the same thing with a mobile phone. Set the camera up to take the picture and tap the point on the screen where you want the sharpest focus. A yellow square will appear at that point.

Depth of field

Depth of field means the amount of the image that is in focus from front to back. This is controlled by the size the of the hole that lets light into the camera – the aperture. Big aperture – a large hole – means small depth of field. Small aperture creates a deep depth of field. Large holes are represented by small numbers like f2.8 or f4 and small apertures by large numbers such as f18 and f22. The larger the number, the deeper the depth of field. In this example (below), the "happy couple" are some way in front of the family and you want to make sure everything is in sharp focus.

The short line represents the happy couple and the tall one the family

Shallow depth of field gives a short focus range so the family are likely to be out of focus

Deep depth of field focuses front to back

Auto risks both front and back losing sharpness Range in focus

Range in focus

Range in focus

Taking Control

Aperture priority lets you control the size of the hole. If you use a small hole, for maximum depth of focus, this may create another problem. A small aperture lets in less light and that means a dark picture or a longer shutter speed – which risks camera shake. This is why wedding photographers like bright days and always have a tripod handy just in case.

When to Avoid Focusing on Everything

There are times when you may not want all of the image in focus. For a portrait of a person, animal or plant you may want to blur the background to concentrate the viewer on your subject. So a shallow depth of field (a large hole and a small f number) allows you to do just that. For the swallowtail butterfly, I have used a shallow depth of field which has blurred the background so the viewer’s attention remains on the beast. The icy tree catches the light. Again a shallow depth of field prevented the foliage behind it from intruding. It is rare that you want the front of your photograph blurred. But you may want a distant subject to be as sharp as possible – such as mountains or a cityscape. You may not be interested in what is at the front of the image. The seascape concentrates on the rocks and waves but there is still substantial depth of field so the clouds and the front waves are still just in focus. But they are only just in focus which helps draw the eye back to the rocks and the crashing waves. The skyscape is focused on the treeline, which was over 100 metres away. This gives a sharp baseline to take the eye up into the clouds.

Trying it Out

Set your camera to a single point of focus and on aperture priority. Put it on a tripod or somewhere steady. Point it at a range of objects at different distances so they will all be included in your pictures. A diagonal line of plants or posts would work well. Focus on the central object and set the aperture to as small a number as you can. Increase the aperture for each photograph until you reach the highest available. Download onto a computer and see the differences.

I hope you enjoy the results and if you fancy meeting some fellow photographers please get in touch on

stevemarshall128@gmail.com