Voyages of Exploration and Discovery

Voyages of Exploration and Discovery

Launched on August 20, 1977, Voyager 2 moved on an arcing trajectory past the orbit of Mars, through the asteroid belt, to approach the Jupiter system and thread its way past the planet and among its fourteen or so moons.

Jupiter is surrounded by a shell of invisible but extremely dangerous high-energy charged particles. The spacecraft must pass through the outer edge of this radiation belt to examine Jupiter and its moons close up, and to continue its mission to Saturn and beyond.

However, the charged particles can damage the delicate instruments and fry the electronics. Besides, Jupiter is also surrounded by a ring of solid debris, discovered by Voyager I, which Voyager 2 had to traverse. A collision with a small boulder could have sent the spacecraft tumbling widely out of control, its antenna unable to lock on the Earth and its data lost forever.

Voyage to Earth. These voyages of exploration and discovery are the latest in a long series that have characterized and distinguished human history. Carl Sagan, Cosmos Image : © Megan Jorgensen (Elena)

Just before encounter, the mission controllers were restive. There were some alarms and emergencies, but the combined intelligence of the humans on Earth and the robot in space circumvented disaster.

Voyager’s passage by Jupiter accelerated it toward a close encounter with Saturn. Saturn’s gravity has propelled it on to Uranus. After Uranus it plunged on past Neptune, leaving the sloar system, becoming an interstellar spacecraft, fated to roam forever the great ocean between the stars.

Voyager relies on a small nuclear power plant, drawing hundreds of watts from the radioactive decay of a pellet of plutonium. Its three integrated computers and most of its housekeeping functions – for example, its temperature-control system – are localized in its middle. It receives commands from Earth and radios its findings back to Earth through a large antenna, 3.7 meters in diameter.

There are many scientific instruments – ultraviolet and infrared spectrometers, devices to measure charged particles and magnetic fields and the radio emission from Jupiter – but the most productive have been the two television cameras, designed to take tens of thousands of pictures of the planetary islands in the outer solar system.

Most of the scientific instruments of Voyager are on a scan platform, which tracks Jupiter or one of its moons as the spacecraft hurtles past.

Terraforming of Mars - Vaporizing Caps

Terraforming of Mars - Vaporizing Caps

The general concept is called terraforming: the changing of an alien landscape into one more suitable for human beings. In thousands of years humans have managed to perturb the global temperature of the Earth by only about one degree through greenhouse and albedo changes, although at the present rate of burning fossil fuels and destroying grasslands and forests we can now change the global temperature by another degree in only a century or two.

These and other considerations suggest that a time scale for a significant terraforming of Mars is probably hundreds to thousands of years. In a future time of greatly advanced technology we might wish not only to increase the total atmospheric pressure and make liquid water on Mars possible but also to carry liquid water from the melting polar caps to the warmer equatorial regions of the planet. There is of course a way to do it: we would built canals.

In fact, the power of Lowell’s idea may, just possibly, make it a kind of premonition. His canal network was built by Martians. Even this might be an accurate prophecy If the planet ever is terraformed, it will be done by human beings whose permanent residence and planetary affiliation is Mars. The Martians will be us.

Sphère noire. In all chaos there is a cosmos, in all disorder a secret order (Carl Jung). Photo : © Elena

To vaporise the caps of Mars we must heat them. Perhaps we could dust them with a dark powder, heating them by absorbing more sunlight, the opposite of what we do to the Earth when we destroy grasslands and forests. But the surface area of the caps is very large. The necessary dust would require 1,200 Saturn 5 rocket boosters to be transported from Earth to Mars; even then the winds might blow the dust off the polar caps.

A better way would be to devise some dark material able to make copies of itself, a little dusky machine which we deliver to Mars and which then goes about reproducing itself from indigenous materials all over the polar caps. There is a category of such machines. We call them plants, and some are very resilient and hardy.

Terraforming: Could we in some sense make Mars inhabitable? Illustration: © Elena

We know as well than at least some terrestrial microbes can survive on Mars. What is necessary, is a program of artificial selection and genetic engineering of dark plants – perhaps lichen – that could survive the much more severe Martian environment. If such plants could be bred, we might imagine them being seeded on the vast expanse of the Martian polar ice caps, taking root, spreading, blackening the ice caps, absorbing sunlight, heating the ice, and releasing the ancient Martian atmosphere from its long captivity.

We might even imagine a kind of Martian Johnny Appleseed, robot or human, roaming the frozen polar wastes in an endeavor that benefits only the generations of humans to come.

If we terraform Mars, it will look like this. Photo : Elena

Stars as Friends

Stars as Friends

After Eratosthenes’ discovery, many great voyages were attempted by brave and venturesome sailors. Their ships were tiny, they had only rudimentary navigational instruments, they used dead reckoning and followed coastlines as far as they could. In an unknown ocean they could determine their latitude, but not their longitude, by observing, night after night, the position of the constellations with respect to the horizon. The familiar constellations must have been reassuring in the midst of an unexplored ocean.

The Mediterranean world at that time was famous for seafaring. Alexandria, in Egypt, was the greatest seaport on the planet. Once you knew the Earth to be a sphere of modest diameter, would you not be tempted to make voyages of exploration, to seek out undiscovered lands, perhaps even to attempt to sail around the planet? Four hundred years before Eratosthenes, Africa had been circumnavigated by a Phoenician fleet in the employ of the Egyptian Pharaoh Necho. The set sail, probably in frail open boats, from the Read Sea, turned down the east coast of Africa up into the Atlantic, returning through the Mediterranean. This epic journey took three years, about as long as a modern Voyager spacecraft takes to fly from Earth to Saturn.

The stars are the friends of explorers, then with seagoing ships on Earth and now with spacefaring ships in the sky. Image : Elena

Stars High in the Sky

Some stars, the supernovae are as bright as an entire galaxy that contains them; others, the black holes, are invisible from a few kilometers away.

Some stars shine with a constant brightness; other flicker uncertainly or blink with an unfaltering rhythm.

Some rotate in stately elegance; others spin so feverishly that they distort themselves to oblateness.

Most shine mainly in visible or infrared light and others are also brilliant sources of X-rays and radio-waves.

Blue stars are hot and young; yellow stars, conventional and middle-aged; red stars, often elderly and dying; and small white or black stars are in the final throes of death.

Let’s remind you that the Milky Way, one of the billions of galaxies, contains some 400 billions of stars of all sorts moving with orderly and serene grace.

Music of the Galaxy

Music of the Galaxy

In the great dark between the stars there are clouds of gas and dust and organic matter. Dozens of different kinds of organic molecules have been found there by radio telescopes. The abundance of these molecules suggests that the stuff of life is everywhere. Perhaps the origin and evolution of life is, given enough time, a cosmic inevitability. On some of the billions of planets in the Milky Way Galaxy, life may never arise. On others, it may arise and die out or never evolve beyond its simplest forms. And on some small fraction of worlds there may develop intelligences and civilisations more advanced than our own.

Is our planet the one lonely theme in the music of life? Image © Megan Jorgensen (Elena)

All life on Earth is closely related. We have a common organic chemistry and a common evolutionary heritage. As a result, our biologists are profoundly limited, as they study only a single kind of biology, one lonely theme in the music of life.

Is this faint and reedy tune the only voice for thousands of light-years? Or is there a kind of cosmic fugue, with themes and counterpoints, dissonances and harmonies, a billion different voices playing the life music of the Galaxy?

About Jupiter

About Jupiter

Jupiter is surrounded by a shell of invisible but extremely dangerous high-energy charged particles. The spacecraft must pass through the outer edge of this radiation belt to examine Jupiter and its moons close up, and to continue its mission to Saturn and beyond.

But the charged particles can damage the delicate instruments and fry the electronics. Jupiter is also surrounded by a ring of solid debris, discovered four months earlier by Voyager I, which Voyager 2 had to traverse.

A collision with a small boulder could have sent the spacecraft tumbling wildly out of control, its antenna unable to lock on the Earth, its data lost forever. Just before encounter, the mission controllers were restive. There were some alarms and emergencies, but the combined intelligence of the humans on Earth and the robot in space circumvented disaster.

Stellar Bodies. Image: Elena

Voyager’s passage by Jupiter accelerated it toward a close encounter with Saturn. Saturn’s gravity will propel it on to Uranus. After Uranus it will plunge on past Neptune, leaving the solar system, becoming an interstellar spacecraft, fated to roam forever the great ocean between the stars.