This is a generally open thread!

During the troubling times of my life, I’ve always found a certain refuge in science and nature. Knowing that whatever idiotic pathway humans invent to tumble down and likely destroy the world, nature will always have the last laugh. I find some comfort in that. So, without further ado, here’s some science to cogitate on!

The Voyagers

August and September represent the 40th anniversary of the launch of Voyager 2 and Voyager 1 space probes, respectively. As of next month, both these space probes will have been flying through space for 40 years. Both are still operational and sending back data to us.

Voyager 2 was the only spacecraft to have flown by our 4 gas giant planets--Jupiter, Saturn, Uranus, and Neptune--and has been the only spacecraft to fly by the last two of those. Voyager 1 flew by only Jupiter and Saturn.

However, Voyager 1 managed a huge first for humankind. It became the first (and so far only) operational spacecraft to enter interstellar space in August 2012. Our Sun is surrounded by something called a heliosphere, an area of space where the Sun’s solar wind dominates the “flow” of particles in space. Outside of the heliosphere, the interstellar winds of all the stars in the galaxy take over the dominating force. The edge of the heliosphere, where one goes from our Sun dominating to the interstellar winds dominating, is called the heliopause.

So, we officially have one interstellar space probe!

Voyager 2 will enter interstellar space at some point within the next 3 years.

Our solar system is very large. It takes approximately 40 years (plus or minus) to traverse through it into interstellar space traveling at about 30,000 miles per hour!

What Is Interstellar Space Like?

Voyager 1 is currently about 13 billion miles from the Earth. It has discovered that cosmic rays--high-energy atoms stripped of their electrons--are 4 times as common outside the heliosphere. Cosmic rays could potentially be deadly at high levels, so in effect, our heliosphere (and the Earth’s atmosphere) are both serving as shields against this high-energy galactic radiation. Some cosmic rays still get through to us, however, and they often affect electronics. In one case, it is thought that cosmic rays were probably responsible for a Qantas Airbus 330 airliner in 2008 unexpectedly plunging hundreds of feet two times. Many people were injured in that incident--some seriously.

Besides the high cosmic ray concentrations, Voyager 1 also discovered that the interstellar medium has created a magnetic field that is wrapped around our heliosphere, and that it likely makes our heliosphere very spherical. Previously, it was thought that our heliosphere was “comet shaped” with a long, lingering tail (sort of like a boat pushes up water into a mini wave at its bow, but behind it is a long rippling tail as it moves through the water). But with the help of Voyager 1, there are strong hints this is not the case, and that there are equal pressure waves on all sides of the Sun as it moves through space. This was not expected.

Where Next Voyagers?

The Voyager probes use radioisotope thermoelectric generators for electricity and heat generation--in other words, tiny nuclear engines. The radioisotopes will have degraded so that by between 2025 and 2030 both spacecraft will no longer be able to power any of its instruments, although a communications “ping” might still be possible with the spacecraft until 2037 or so.

Also, the flight engineers for the Voyagers are aging out! They are the ones who know all about the 1970s technology that the spacecraft run on! Some are already retiring. See this New York Times article from a few days ago:

https://www.nytimes.com/2017/08/03/magazine/the-loyal-engineers-steering...

Where will our interstellar spacecraft be headed? Neither is headed towards the nearest stars, but both will each pass by different stars about 40,000 years from now. (Just for reference, 40,000 years ago is when Neanderthals died out here on Earth.)

Both Voyagers will continue flying through space until they happen to run into something--perhaps they will be flying for hundreds of millions of years. Both contain a golden audio-visual record, which contains photos from the Earth, music (Chuck Berry and Mozart among others, such as various indigenous musics and even whale songs), a message from the United Nations and the president of the United States, and greetings in 55 languages among other things.

Sources (besides the link above):

https://en.wikipedia.org/wiki/Voyager_1

https://en.wikipedia.org/wiki/Cosmic_ray

https://www.nasa.gov/feature/goddard/2017/nasa-s-cassini-voyager-mission...

https://www.jpl.nasa.gov/voyager/

https://www.jpl.nasa.gov/voyager/news/details.php?article_id=48

Link to the previous Science Escape article:

https://caucus99percent.com/content/science-escape-1-universe