Voyagers to the Stars

Voyager: One who takes a long and sometimes dangerous journey involving travel by sea…or in space.

Forty years ago two intrepid spacecraft, aptly named Voyager 1 and 2, set off on a remarkable journey dubbed the “Grand Tour” to visit the gas giants in the outer solar system. Launching Voyager 2 on August 2 and Voyager 1 on September 5, 1977, NASA took advantage of an alignment of the outer planets that made it possible (economically and energy-wise) to visit at least Jupiter and Saturn and potentially Uranus and Neptune. This alignment wouldn’t occur again for 176 years.

Voyager (Image courtesy of NASA)

Although Voyager 1 launched after Voyager 2 it took a faster path and arrived at Jupiter ahead of Voyager 2. Voyager 1 flew by Jupiter and used the gas giant’s gravity to boost its speed and change direction to head off toward Saturn, retracing Pioneer 11’s journey to Jupiter and Saturn earlier in the decade. The trajectory Voyager 1 had as it approached the ringed giant dictated that it was destined to head out of the solar system above (or north of) the ecliptic, the imaginary plane in which the planets orbit the sun.

NASA had to make a decision with regard to Voyager 2: If Voyager 1 did not successfully complete its pass by Saturn, gathering data on the planet’s largest moon, Titan, Voyager 2’s trajectory would be adjusted to make up for its twin’s shortcomings, otherwise it would encounter the ringed planet and slingshot out to Uranus. To all our benefit, Voyager 1 completed its mission and Voyager 2 went on to visit the ice giants, Uranus and Neptune.

Uranus as seen by Voyager 2. (Image courtesy of NASA/JPL)

Neptune as seen by Voyager 2 (Image courtesy of NASA/JPL)

The probe was not designed from the start to encounter the last two distant planets, but it was designed to be reprogrammed on the fly. So NASA engineers rewrote Voyager 2’s programming to account for the much lower light levels at these greater distances from the sun, allowing the probe to capture the first closeup images of Uranus and Neptune. In 1989, after its encounter with Neptune, Voyager 2 took a southerly path below the ecliptic plane and off toward interstellar space.

Today, both probes are still transmitting data from a half dozen or so instruments, their optical cameras and infrared sensors have long since been shut down to conserve power. Notably, Voyager 1 has passed the boundary between the sun’s influence in our solar system and interstellar space known as the heliopause. We find Voyager 1, the most distant object man has ever sent into space, moving beyond 21 billion kilometers (12.9 billion miles) moving at a speed of 61,000 kph (38,000 mph). It takes almost 19.5 hours for a data transmission to reach Earth from Voyager 1 moving at the speed of light. Voyager 2 is a bit closer at 17 billion kilometers (10.5 billion miles) and is moving slower at about 56,500 kph (35,000 mph) with a transmission time of almost 16 hours.

The radio that the probes carry only transmits at 23 watts. That’s about 5 times a typical cell phone’s transmission power we carry around with us. Since the strength of the signal is reduced by the square of the transmission distance, the signal that we receive from Voyager 1 is really, really small: a tenth of a billionth of a trillionth of a watt. That’s .0000000000000000000001 watts. A very small number! To try to put this is some sort of perspective (and even this is hard to grasp!):

If you dropped a grain of salt from the tabletop to the floor, the energy contained in that grain of salt is 10 x 1 million x 1 billion times larger than the energy contained in Voyager’s signal for one second!

As amazing as it is that these spacecraft have been in space for 40 years and are at these extreme distance, to me, it’s even more amazing that we can detect these signals. We use a network of radio telescopes called the Deep Space Network (DSN) that are superbly designed to pick up these astonishingly small signals. There are three sites across the globe that contain multiple radio telescopes to maintain communication with the distant probes in space. The are located in Canberra Australia, Madrid, Spain and Barstow, California (Goldstone). The facility in Canberra is the only site that has a view of Voyager 2 as it exits the solar system to the south, consequently Canberra had to have its antenna dish increased in diameter in 1987 from 64 meters to 70 meters to be able to track Voyager 2’s diminishing signal.

Radio Telescope, Canberra Au. (Image courtesy of NASA)

The Voyagers will eventually stop transmitting around 2030 as their radioisotope thermoelectric generators (RTGs) finally are depleted. The probes will continue on their respective journeys unimpeded. They will not slow down and will not change direction unless something, or someone interferes with them. They may survive for tens of millions of years – a calling card with a Golden Record carrying representations of the inhabitants from a nondescript little water-planet orbiting a very run-of-the-mill star in an arm of the Milky Way Galaxy.


  1. Check on the latest status of Voyager 1 and 2:
  2. Indepth review of Voyager 2’s mission:
  3. A nice review of the Voyager missions:

Till next time,

RC Davison

Cassini’s Garden

Wallpaper - Cassini's Garden

Cassini’s Garden

Cassini’s Garden was originally created to commemorate the amazing probe that has been in space for almost 20 years and orbiting Saturn and collecting data since 2004. But, it’s not just the machine, it’s the international group of people that worked together to make the mission happen.

Originally known as Cassini-Huygens, which identifies the Huygens lander that was carried onboard Cassini and successfully touched down on Saturn’s largest moon, Titan, on January 14, 2005. Huygens was provided by the European Space Agency (ESA) and along with the Italian space agency, Agenzia Spaziale Italiana (ASI) and NASA formed the three partners for the mission. In total there were 17 countries involved in the mission. In all, over five thousand people have touched this mission since its development began in 1990; from engineers, technicians, designers, machinists, scientists, astronomers and a host of other specialists from around the world.

The Cassini mission has exemplified the best of what we can do when we cooperate together; something that is painfully lacking around the world today when it is needed most. The data produced by this mission is available to everyone – everybody on this planet benefits from the international cooperation that gave birth to Cassini-Huygens.

Cassini’s Garden shows a monument to the enduring probe that has been erected on Enceladus sometime in the future when we humans are no longer defined by our differences.

The probe has had a few problems during its tour but nothing that has diminished its mission nor prevented it from being extended two more times after its initial 4 year jaunt. The only thing that has forced Cassini to end its mission now is that it is running out of fuel, and to prevent it from potentially contaminating Titan or Enceladus with microbes from Earth, it will be directed to fly into Saturn on September 15, 2017. Truly a sad day for everyone involved with this noble machine or that have followed its mission over the years.

And, speaking of potential for life, a paper has recently been published discussing the data Cassini has collected from a fly-through of the plums of water ice and gas venting from the small moon Enceladus’ southern pole in October of 2015. This data revealed the presence of molecular hydrogen (H2) in the gas/ice cloud, which was mostly water.  The presence of hydrogen indicates that there may be hydrothermal vents on the ocean floor of Enceladus.  A chemical reaction between the water and the rocks on the ocean floor, driven by the heat could create the hydrogen. This in turn could be used by bacteria as a food source when combined with carbon dioxide dissolved in the water.

The H2 is not direct evidence of life, but compelling evidence that all the right ingredients are there to support life – probably bacterial – like we see around the hydrothermal vents in our oceans. One more feather in Cassini’s cap!  Check out NASA’s website for more information on this.

Cassini’s Finale – Plunging between the inner rings and Saturn’s atmosphere.

With Cassini setting up to dive between the planet and its inner rings later this month as a finale to its mission, we can expect to see some really amazing images and learn more about this majestic ringed planet than ever before. And, as the data is processed and digested we can expect more revelations about this planet in the years to come.

Thank you to the Cassini team for all their hard work and an amazing ride!

For more information check out Cassini’s Grand Finale.

Till next time,

RC Davison

The Cost of Cassini at Saturn

On June 30, 2014 NASA and ESA (European Space Agency), celebrated ten years of unprecedented scientific discoveries of the planet Saturn and its moons by the Cassini-Huygens probe.

Saturn by Cassini showing the prominent hexagonal formation at the north pole. 8-18-14 Credit: NASA/JPL-Caltech/Space Science Institute

The probe has returned well over 350,000 images of the ringed system; discovered seven new moons orbiting the planet, successfully landed the Huygens probe on the surface of Saturn’s largest moon, Titan; over four thousand research papers have been written based on Cassini’s findings; “tasted” the water from Enceladus’ geysers and will continue to send back data until 2017 when it will be intentionally flown into Saturn’s atmosphere.

When we look at all that Cassini has delivered, one can ask – is it worth the $3.27 billion dollars the mission has cost? That’s a whole lot of money!

Titan and Rhea, Saturn’s largest two moons. Image credit: NASA/JPL-Caltech/Space Science Institute

But, when you consider that the mission actually started development in 1990, the cost turns out to be about $130.8 million per year over the last 25 years. Still a lot of money. But, the cost per person in the United States is about $0.42 per person per year (based on an average populate of the US from 1990 to 2014).

The $3.27 billion is the total mission cost to date, but the United State’s contribution was actually $2.6 billion, the balance being supplied by ESA and the Italian space agency, so the per person cost for the US is actually more like 33 cents per person. The per person contribution gets even smaller when you divide the cost by the populations of the ESA supporting countries.

Yes, $3.27 billion is a lot of money, but when you look at it from the perspective of real cost over time it’s not even the cost of a pack of gum per person per year! The flip side of this expense is that the mission development and support employed over 5000 people. That is money that went back into the economy; it put food on the table, paid bills, stimulated local businesses and economies, new technology development, advanced our

Saturn’s amazing rings! Image credit: NASA/JPL-Caltech/Space Science Institute

understanding of the Solar System and of the Saturnian system immensely. The most important contribution (albeit the hardest to quantify) was to excite and encourage a new generation of young people to pursue careers in science and technology.  This one item is so very important in today’s competitive world economy. The return-on-investment is still paying off and will so for many years to come.

As a point of reference, the US Defense Department budget for just 1989 was $389 billion dollars!  For 2014 it is $752 billion.  That works out to $2350 per person today!  $3.27 billion over 25 years doesn’t sound quite so big does it?

Saturn back-lit by the Sun with Mars, Venus and Earth. Image credit: -Caltech/SSI

Take a few moments and check out NASA and ESA’s sites for Cassini and take a look at the amazing images that have been sent back by this enduring probe.  After all, you paid for it!

Check out this video for what to expect for the rest of Cassini’s mission at Saturn.

Till next time,

RC Davison

NASA’s Proposed 2013 Budget – NOT An Investment In Our Future!

The Obama administration released its 2013 proposed budget for NASA.  A step in the wrong direction!!

If one looks at the fact that NASA’s budget of $17.7 billion is 0.47% of the proposed national budget of $3.8 trillion, and they’re proposing a cut of .3% of NASA’s 2012 budget, which works out to $59 million. Now, is that $59 million really going to help reduce the national debt—or will it just get lost in the pork-barrel legislation that seems to be prevalent? When you consider the impact it has on NASA and its plans for future space exploration and the benefits it will bring, is it really worth it? These projects stimulate employment and provide opportunities for technological spinoffs that can further stimulate the economy. And, we’re not even talking about the educational benefits by getting young people interested in and excited about science and engineering.

Speaking of education. Why in the world, with our decaying education system, would you cut NASA’s education budget? Cut by $36 million from 2012’s allotment of $136 million—26%! We have no business cutting any educational programs. If we want to save money we should be looking at how we can run them more efficiently and put more children into the programs. This is an investment in our future. Our 401K for the nation is the education of the children today. We can’t afford to let our technical edge get any duller than it is now.

Consider the benefits of raising NASA’s budget by just $59 million (.001% of the national budget). We would be joining the European Space Agency in two missions to Mars in 2016 and 2018. We would be able to expand the educational programs and further development of flagship mission that push the boundaries of space exploration. Just think about what we have learned from the Pioneers, Voyagers, Cassini, Galileo, the Mars rovers Spirit and Opportunity to name a few.

I know times are tough. I feel it every day as does everyone else. But, our government seems to be flailing about in a panic to leave nothing untouched in the effort to reduce the budget. Is that for the good of the country or just PR for the next elections? It seems to be Republicans pointing fingers at Democrats and visa-versa. Aren’t we all on the same team—team USA? I don’t get the feeling that we are seriously weighing the consequences of some of these cuts, the perceived benefits we see today won’t pay off tomorrow.

If we don’t carefully invest in our future, our future will be very bleak indeed…

Check this link to Universe Today for a review of the budget.

Till next time,

RC Davison