Watching the new J.J. Abrams-directed Star Trek Into Darkness a couple of months ago, I was excited to hear the familiar introductory speech: "These are the voyages of the starship Enterprise. Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no man has gone before."
And guess what? In reality, 35 years on, we as humans have reached the final frontier: the edge of our solar system. The two unmanned probes Voyager 1 and Voyager 2, launched in 1977 as part of the mission to study Jupiter and Saturn, have actually exited the Solar System, although precisely where the boundary of our system lies is unclear. As it turns out, the space probes were able to not only journey to Uranus and Neptune but continue into deep space. At some point soon (this uncertainty is not due to the unpredictability of traffic in deep space but to our lack of knowledge of the probes' precise paths!), Voyager 1 and Voyager 2 will become the first man-made objects to ever exit our solar system, a momentous achievement for humankind.
Less than 400 years after mastering the law of gravity, we have developed the technology to escape its attractive grip and leave our solar neighborhood. This remarkable feat is testimony to the curiosity of the human mind and the power of science and technology.
Voyager 2, launched Sept. 5, 1977, was put on a path that capitalized on an unusual alignment of the planets that occurs every 177 years; it would graze past Jupiter, Saturn, Uranus, and Neptune. Its sister probe, Voyager 1, was launched 16 days later and was put on a shorter and faster trajectory to bring it close to Jupiter and Saturn sooner.
Both Voyager probes exploited the immense gravitational pull of Jupiter to hurl themselves on to Saturn. This attractive force increased their speed measured relative to the Sun by roughly 35,700 miles per hour. Since the total energy within the Solar System must be conserved, this push given to the probes caused a very slight slowdown of Jupiter's own orbit around the Sun (but by only one foot per trillion years).
Both probes are now billions of miles from Earth. At that distance, it takes radio signals traveling at the speed of light 17 hours to reach us (to see exactly how far they are hurtling in real time, see the odometer on NASA's website here.)
Voyager 1 is currently at the junction where the magnetic field of the Sun melds with the magnetic field of interstellar space. This is the door through which highly energetic particles from distant supernova explosions and other cosmic events zoom into the Solar System while less energetic particles emitted by our Sun exit. "It's like a highway, letting particles in and out," lead Voyager scientist Ed Stone told reporters at the American Geophysical Union conference in San Francisco late last year. The length of this "magnetic highway" is unknown, and it is for this reason that scientists aren't sure how long it will take for the probes to cross it.
How these probes are powered is itself pretty astounding: They are juiced by the radioactive isotope plutonium-238. Plutonium-238 decays and produces heat that can be captured easily. One gram of plutonium-238 generates 0.5 watts, the energy produced by high-power LEDs on my bike lights. Both Voyager 1 and Voyager 2 are sustained by these nuclear batteries.
The Pioneer probes that preceded Voyager carried small metal plaques identifying their dates and places of origin for the benefit of any future spacefarers who might encounter them. NASA placed a more ambitious message aboard both Voyager probes, a special kind of time capsule intended to communicate the story of our world to extraterrestrials. The Voyager message is carried by a phonograph record, a 12-inch gold-plated copper disk containing sounds and images selected to portray who we are and the diversity of life and culture on Earth, including 115 images and a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales, and other animals. To this, they also added musical selections from different cultures and eras and spoken greetings from Earth people in 55 languages.
With an exciting program of Mars exploration recently announced by NASA, and coupled with the incredible finding of more than 800 extrasolar planets in our backyard, there is guaranteed work for creative, well-trained, enthusiastic scientists and engineers to do for generations to come. Let's hope that we can continue to inspire and encourage our young people to enter the fields of science and engineering and fulfill these amazing human dreams.
In his 1994 book Pale Blue Dot: A Vision of the Human Future in Space, Carl Sagan examined the claims made through history that the Earth and the human species are unique. Sagan, a participating scientist in NASA's Voyager program, was a strong proponent of space exploration and, in particular, of exploring other planets in the solar system. He argued that the endgame needed to be protection of the Earth and the extension of human habitation beyond it.
We are at a critical moment now with climate change, and the need to preserve our planet is more important than ever. Will we, India, China and the rest of the world take bold decisions to minimize our impact on the environment, or will we miss this clarion call and bring catastrophe upon ourselves? We need to make sure that the Voyager probes carrying a record of human civilization speeding beyond our solar system remain an introduction to the world that sent them and not an epitaph for a civilization that caused its own ruin.