Thousands of radio listeners in the United States panicked on Halloween night 1938 when a dramatisation of H G Wells's fantasy The War of the Worlds convinced them that Martians were invading New Jersey and New York. Now we humans are poised to invade right back.
The European Space Agency's (ESA) Mars Express orbiter, carrying the British-built lander Beagle 2, left Earth on June 9 bound for Mars. The next day the United States space agency (NASA) launched the first of two rovers as part of its on-going Mars Exploration Program; the second rover headed into space on June 28. All three flights should reach Mars in January 2004. The Japanese orbiter NOZOMI (Planet B) is currently en route and will also arrive at Mars in early 2004.
Why the flurry of activity? Over the next few months Mars will be closer to the Earth than at any time in recorded history, cutting the journey to less than seven months. The primary scientific objective of the NOZOMI program will be to study the upper atmosphere, which is thought to be under the strong control of the solar wind because of
Mars's weak magnetic field1. Meanwhile down on the ground, the European and American rovers will be looking for Martians.
The Dunes of Mars
One of the many compelling questions about Mars is whether or not it was ever capable of supporting life. The more we learn, the less certain we become of the answer. The story of ancient Mars can be read from its craters, volcanoes, and canyons. Recent missions have compiled a record of processes now at work. What we don't understand is what happened during the billions of years in between. There is evidence for three scenarios:
- A thick atmosphere and perhaps water on the surface, capable of supporting life. Carbon dioxide eventually was lost to space or locked up in carbonate minerals that have so far eluded detection.
- A wintry world surrounded by a fairly thin atmosphere, with water locked up in groundwater. Orbital shifts and volcanism led to periodic warming when life could exist.
- Climate variations but insufficient to sustain life. Meteor impacts pumped heat and water-rich materials into the atmosphere, but then the planet returned to its frozen state.
We know that surface water is necessary for life to exist. Some researchers think that the plains of the northern hemisphere were once the bed of a vast ocean that was replenished by outflows from the southern highlands. But if so, where did the water go? Mars Express will attempt to answer this question by looking at three areas. One, it will study the atmosphere, looking in part for evidence of water escaping into space. Two, it will check the planet's surface for the carbonate sediments that would indicate past presence of water. Finally, it will attempt to probe the planet's crust to a depth of two or three miles, looking for water ice or underground aquifers.
We know that Mars is now a dry, windy place, with huge, sometimes planet-wide, dust storms lasting for months, and sand dunes and dust devils wandering the planet. The Mars Orbital Camera has photographed dark colony-like blotches on dunes located on the floors of craters in the polar regions. Scientists are debating whether the spots are caused by the evaporation and re-freezing of carbon dioxide ice or else are colonies of Martian micro-organisms that flourish in the Martian spring. Unfortunately no landing is planned near the poles. Beagle 2 and NASA's rovers will land and confine their explorations nearer to the equator. But instruments on board Mars Express can observe selected areas at high resolution, so we hope to learn more about the dark dunes. Stay tuned.
The Dunes of Kitty Hawk
On 17 December 1903, man took his first step toward space. At Kitty Hawk, North Carolina, Wilbur and Orville Wright achieved the first manned, controlled, powered flight. They made four short flights that day. The longest of them lasted 57 seconds, and the last wrecked their plane. The brothers had largely constructed the plane in their bicycle repair shop on the west side of Dayton, Ohio, and they had carried it to North Carolina in pieces, buying the wood for wing spars en route, in Virginia. After using the soft sands and steady winds off the North Carolina coast to experiment with the first Flyer, the Wrights returned home to refine their invention. They built two more planes in their Dayton shop and went on to establish the world's first aviation school at Huffman Prairie Flying Field, which is located on what is now the edge of Wright-Patterson Air Force Base, one of the biggest Air Force
bases in the country and a centre for military flight research.
This year we're celebrating the centennial of powered flight. Ohio's auto license plate is tagged 'Birthplace of Aviation', but North Carolina begs to differ. The blurb on the US Mint's Web site underplays Ohio's role in the design and development of the various Wright gliders and motorized Flyers. It describes the plane on the Ohio commemorative quarter simply as 'an early aircraft'. But no matter; the event deserves celebrating no matter where it happened. The US Centennial of Flight Commission Web site has a calendar of events with information about and links to events all over the globe.
It took the human race tens of thousands of years to move from the African savannah to the skies over Kitty Hawk, but less than three-quarters of a century to leap from the skies to outer space. After setting foot on the moon in the late 1960's, however, we've mostly
contented ourselves with research using unmanned probes and trips to the International Space Station. A visit to another planet like Mars would seem the next logical step, but to my knowledge there are no manned missions being planned. Perhaps the political will is missing, because I doubt that man is any less curious than he was thirty-odd years ago.
Throwing Oneself at the Air
Back in February after the Columbia Shuttle broke apart as it was re-entering Earth's atmosphere, someone wrote a letter to the editor of my local newspaper asking 'Can space exploration be made safe?' The short answer, I suspect, is no. It can certainly be made safer, and almost certainly will be, once someone figures out how to make some money at
it2. But space is a dangerous place. We can't breathe there. It's impossibly cold. And other planets are sure to be hazardous to creatures that evolved to live on this one. Shoot, THIS planet will kill you if you don't watch your step.
But doing dangerous stuff is what humans are about. Ever since Icarus came to grief, man has been throwing himself at the air until, a century ago, he managed to stay aloft for 57 breathless seconds. And he hasn't looked back. Now he's throwing himself at the vacuum and daring it to tell him that he doesn't belong there. Perhaps one day soon he'll be off to Mars, a cold and unfriendly place, where he will discover, if not Martians, a new and reinvigorated version of Earthling.
Want to visit Mars from the safety of your computer? Check out the BBC Mars Guide or the Hitchhiker's Guide entry about Mars. And is there a pyramid on Mars? See what our fellow researchers have to say about it.
And don't panic.
million) and will require rigorous medical examinations and training to qualify.