by Lucy Hawking
“Over there!” said George, spotting a sign on a huge pair of double doors. It read, CLEAN ROOM. “Is that where the suits are?”
“That’s it!” said Annie. “I remember it now. I’ve never been inside, but it’s where they keep all the equipment that goes into space. It’s a super-duper clean environment so that bugs and stuff don’t go from Earth into space.”
“Oh yes,” said Emmett nerdily. “It’s very important that microbes don’t travel into space with any of the machinery. Otherwise how would we ever know if we’ve found evidence of life in space or whether we’re just seeing fingerprints that we ourselves left out there?”
Annie ran over to the double doors. “Follow me!” she said. “Most of the people should be upstairs, watching the launch.”
They went through, expecting to emerge in the Clean Room, but there was a surprise in store for them. They found themselves standing on a moving conveyor belt. Gusts of air started blowing at them from all sides as the belt dragged them along. Brushes emerged from the ceiling as they were sprayed with jets and buffed with a huge piece of fabric.
“What’s happening?” shouted George.
“We’re being cleaned!” Annie called back.
“Arrghh!” shouted Cosmos. “They’re messin’ with my ports!”
George saw a pair of robotic arms in front of him pick Annie up and drop her into an all-in-one white plastic suit, pop a hat on her head, a mask on her face, and a pair of gloves on her hands. Before she had time to call out, she was ejected from the conveyor belt through another set of double doors, and it was his turn. George and then Emmett behind him were similarly outfitted by the machine and propelled through the doorway, where they stood, blinking at the incredible whiteness that surrounded them.
It was, thought George, like being inside a set of someone’s very white teeth. On one side of the kids was a robot under construction; on the other, what looked like half a satellite. Everything seemed to gleam with an unusual brightness. Even the air felt somehow thinner and more transparent than normal air. On the wall, a sign read: 100,000.
“That’s how many particles the air has in here,” whispered Emmett through his face mask. “This isn’t the cleanest Clean Room. In there, they have a ten thousand rating—that means any cubic foot of air in there has no more than ten thousand particles in it larger than half a micron! And a micron is a millionth of a meter.”
“Is it clean enough for us to go to Mars from here?” asked George. “I mean, what if we take some evidence of life on Earth to Mars and then Homer finds it later on? Could we mess up the research program?”
“Theoretically, yes,” said Emmett, who was sounding much more confident now that he felt they’d entered his area of expertise. “But that depends on a) whether we can get Cosmos working, b) whether you actually manage to get to Mars, and c) whether Annie’s alien message really is a threat to destroy the Earth. If she’s right—and I have to point out the probability is very low—then if you don’t go, there won’t be life on Earth, anyway. So it won’t matter.”
In a corner of the Clean Room, Annie had found some space suits, but they were bright orange and didn’t look at all like the ones George remembered from his travels around the Universe in the past.
“These aren’t ours!” Annie said in disappointment. “These are the ones they use for the space shuttle—they’re different from the ones me and my dad had.” She rooted around a bit farther. “Dad told me he’d put ours in here for safekeeping,” she said. “And I said, what if someone else took them by mistake? And he said they wouldn’t because he’d labeled them as prototype suits, not to be used for shuttle missions.”
Emmett was tearing at the plastic wrapping that the Clean Room entry machinery had used to cover Annie’s backpack. He fished Cosmos out—and at the same time found the bright yellow book, The User’s Guide to the Universe.
“Okay, little computer,” he said, flexing his fingers. “Operation Alien Life-form is underway. Where to, Commander George?”
“See if you can get him to open the doorway,” said George. “We need to go to Mars, to the north polar region, destination Homer.”
“Bingo!” Annie shouted. “I’ve got the suits!” She emerged with an armful of white space suits in plastic coverings marked PROTOTYPE—DO NOT USE! She chucked one over to George. “Take off your face mask and then put this on over everything else.” She and George ripped the coverings off the suits and started clambering into the heavy space gear.
Meanwhile Emmett had called up some pictures of Mars on Cosmos’s screen, zooming closer and closer to the red planet. However, Cosmos himself was being unusually silent.
“Why is he so quiet?” asked George.
“I had a great idea,” said Emmett simply. “I turned down the volume.”
He turned it up, and they heard Cosmos grumbling, “Nobody cares about me. No one understands me.”
Emmett turned down the volume again.
“We’ll need to be able to talk to Cosmos when we’re out there,” warned Annie. “We got stuck in space once, and once was enough. Can you handle him?”
Emmett turned up the volume once more.
“Do this, do that, that’s all I ever hear,” whined Cosmos.
“Cosmos,” said Annie. “I’ve got a way you can show us how you feel.”
“Bet you want me to open up a doorway so you can go through it,” said Cosmos morosely.
“That’s right,” said George. “But the thing is, we’re not really allowed to do this. So we’ll be in a lot of trouble if we get caught.”
“Cool!” said Cosmos, perking up a bit. “Then I’m in.”
“But we need you to help us,” said George. “We need you to look after us while we’re on Mars. And you too, Emmett. If we need to leave quickly, you have to get us out of there immediately.”
“But,” said Emmett, “if you signal me from Mars, then won’t there be a time delay? I mean, it takes four minutes and twenty seconds for light to travel from Mars. Or, if Mars is on the other side of the Sun, it could be twenty-two minutes. So by the time you’ve said something to me and I’ve replied, it will have taken either eight minutes and forty seconds or forty-four minutes. And that might be too late.”
“No, Cosmos has instant messaging,” said Annie. “So you’ll hear us and reply immediately.”
“Wow! That's some pretty special physics!” said Emmett, looking impressed.
“That is,” Annie added, “if Cosmos isn’t too chicken to do this—”
“Dude. I’m on it,” said Cosmos. A little beam of white light shot out from the great computer. In the middle of the Clean Room, the kids saw the shape of a doorway emerge.
The door swung open. Behind it, they saw a reddish planet coming into view. There was a large dark patch on its middle left-hand side.
“Approaching Mars,” said Emmett as the planet drew closer, stars shining brightly in the black sky behind it. “See that dark spot? That’s Syrtis Major. That’s a huge area of dark, windswept volcanic plain so large, it has been known to science since the first telescope was turned to Mars in the 1600s. The southern polar ice cap is large and visible at this time of year. The bright feature at the lower center is the Hellas Basin, the largest undisputed impact crater on the planet, formed by an asteroid or comet. It is 1,370 miles across. Those four points you see in the equatorial region—they’re clouds of water ice crystals over the four largest volcanoes in Tharsis.”
“How do you know all this?” asked George, speaking in a strange voice through the voice transmitter in the space helmet he had just put on.
“Actually, I’m getting it from Cosmos’s screen,” said Emmett almost apologetically. “He’s giving me a readout of the conditions on Mars to check that it is safe for you to land. On the way he’s giving a bit of tourist advice. It says here that visitors to Mars should remember that gravitational conditions there will be quite different from what you’re used to. You’ll weigh less than half of wh
at you weigh on Earth, so get ready to bounce.”
“Does he say what the weather is like?” Annie asked through her voice transmitter. She sounded rather nervous.
“Let’s look…,” said Emmett. “Here’s today’s forecast for the north polar region of Mars: Today will be mostly clear with an average temperature of minus seventy-six degrees Fahrenheit. Possibility of water ice storms in the area: very low. But dust storms could start from the central region and engulf the planet. I’d better keep an eye on that. It says here that dust storms are common at this time of year and can spread very fast.”
The doorway got nearer and nearer to Mars, breaking through the thin atmosphere and heading down toward the rocky surface.
George and Annie stood at the threshold, holding hands with their big space gloves, their oxygen tanks plugged in and their transmission devices switched on. As they hovered a few yards above the ground, Annie asked, “Are you ready? Five, four, three, two, one…jump!”
They disappeared through the doorway and found themselves on Mars—a planet where no human being had ever set foot before.
Emmett saw them vanish; then a spray of red Martian dust floated through the portal before the door slammed shut.
He tried to capture some of the dust as it drifted through the superclean air, but it was quickly sucked away through the Clean Room’s contamination control system, designed to immediately dispose of any pollution. Like Annie and George, the Martian dust disappeared completely, leaving Emmett alone in the huge room with Cosmos. He gazed around for a few minutes and then picked up The User’s Guide to the Universe.
He looked up Mars in the index and turned to the right page.
“Did Life Come from Mars?” he read.
* * *
THE USER’S GUIDE TO THE UNIVERSE
DID LIFE COME FROM MARS?
Where and when did life as we know it begin? Did it begin on Earth? Or could it have come from Mars?
A couple of centuries ago most people believed that humans, and other species, had been present since the creation of the Earth. The Earth was thought to be the entire material world, and the creation was described as a sudden event, like the Big Bang that scientists believe in today. This was taught in creation stories, like the one in Genesis, the first book of the Bible, and other cultures throughout the world have similar stories of a single moment of creation.
Although some astronomers did think about the vastness of space, its study only really began after Galileo (1564–1642) made one of the first ever telescopes. His discoveries showed that the Universe contained many other worlds—some of which could, like our own planet, be inhabited. The immensity of the Universe—and the evidence that its creation must have happened long before humans arrived on the scene—did not begin to be generally recognized until much later on, in the eighteenth century. During that innovative time the study of rock formation by sedimentation in shallow seas led geologists to understand that such processes must have been going on, not just for thousands or even millions of years, but for thousands of millions of years—what we now call gigayears.
Modern geophysicists now believe our planet Earth—and our Solar System—was formed about 4.6 gigayears ago, when the Universe—now aged about 14 gigayears—was itself just more than 9 gigayears old.
Modern humans appear to have arrived in the rest of the world from Africa fifty thousand years ago, but modern archaeology has shown quite clearly that it was only about six thousand years ago that early human societies began to develop what we call civilization—economic systems with the exchange of different kinds of goods. A very important factor in any civilization is the exchange not just of goods but of information. But how was this information stored or spread?
Before the invention of paper and ink, one of the earliest methods was to use marks scratched on clay tablets—the distant ancestors of modern computer memory chips. This sharing and collection of knowledge, particularly the kind we now call scientific, became an objective in its own right.
The development of civilization depended, of course, on the emergence of what has been called intelligent life—beings with a sufficient sense of self-awareness to recognize themselves in a mirror. There are several known examples on our own planet: elephants, dolphins, and, of course, anthropoids—the group that includes chimpanzees and other apes, Neanderthals, and modern human beings like us. So far no signs of intelligent life have been detected elsewhere in the Universe.
How did intelligent life on Earth come into being? Fossils had suggested the idea that modern plants and animals could have arisen from other life-forms present on Earth in earlier times, but people couldn’t understand how the various species could be so well adapted without having been designed in advance. The idea of continuous evolution became generally accepted only after Darwin (in 1859) explained the principle of adaptation by natural selection. Understanding how this actually works, however, only became possible in the late 1950s, when Watson and Crick made their discoveries about DNA.
This modern DNA-based understanding of the evolutionary process is supported by the fossil record—as far back as it is dated. The trouble is that the record does not go very far back—less than a gigayear, which is only a fraction of the total age of the Earth.
Early, simple life-forms developed before what is known as the Cambrian era. We can see fairly clearly how (though not precisely why) what we should recognize as intelligent life-forms evolved from them over the last five hundred million years. But there is no proper record of how the pre-Cambrian life-forms evolved in the first place.
One problem is that it is only since the Cambrian era that large bony animals, which turn easily into fossils, have been present. Their largest predecessors are believed to be soft-bodied creatures (like modern jellyfish); farther back in time, the only life-forms seem to have been microscopic single-celled creatures. These don’t leave clear fossil records.
Going back even farther, it is evident that evolution must have been very slow. And tricky to achieve. Even if environmentally favorable planets were fairly common in the Universe, the odds against the evolution of advanced life on any single planet would have been very high. This means that it would occur on only a very small fraction of them. Earth must be one of those rare exceptions. And it could still have easily gone wrong. There is a calculation by astrophysicists known as the solar age coincidence. This shows that in the time taken by evolution on Earth to lead to intelligent life, a large part of the hydrogen fuel reserves powering our Sun were used up. In a nutshell, if our evolution had been just a little bit slower, we would never have got here at all before the Sun burned itself out!
So which of the essential evolutionary steps would be the hardest to achieve in the available time?
One difficult step on Earth may have been the beginning of what is known as eukaryotic life—in which cells have an elaborate structure with nuclei and ribosomes. Eukaryotes include large, multicellular animals like us, as well as single-celled species like the amoeba. The fossil record shows that the first eukaryotic life appeared on Earth at the beginning of the Proterozoic aeon, about two gigayears ago, when the Earth was only about half its present age. Before this period, more primitive procaryotic life-forms, such as bacteria (with cells that are too small to contain nuclei), are now thought to have been widespread when the Earth was less than one gigayear old.
There is evidence for the existence of this kind of primitive life right back at the very beginning of this aeon. So we are now faced with a puzzle, because this implies that the whole process by which life actually originated must have occurred during the preceding epoch. This is known as the Hadean aeon, the earliest aeon of the Earth’s history.
Why should this be a problem? Well, the Hadean aeon was certainly long enough—nearly a gigayear—but conditions on Earth at that time would have been literally infernal, as the name suggests (Hades is the ancient Greek version of hell). This was when debris left over from the formation of the Solar System w
as crashing into the Moon and forming craters there. And the Earth—with its greater mass and gravitational attraction—would at that time have been subject to even heavier cratering. This bombardment would have caused frequent reheating of our planetary environment. New life-forms could hardly have avoided being nipped in the bud.
The planet Mars, however, has a lesser mass than Earth and is farther away from the Sun, so it has recently been proposed that the bombardment of Mars could have subsided sooner than that of the Earth. Chunks of debris may also have been frequently knocked off Mars and, in some cases, subsequently swept up by the Earth.
This would mean that life may have originated on Mars—before it could have survived here.
Analysis by electron microscope of a meteorite that did reach Earth from Mars (meteorite ALH8400) has shown structures resembling fossil microbes. This proves that fossil organisms may have reached the Earth from Mars. But that would still not account for life then appearing here unless living—not just fossil—organisms could survive the necessary migration by meteor. This is a question that is currently being very hotly debated.
An even more interesting question is whether the environment on Mars at that time really would have been suitable for primitive life.
Nowadays, conditions on Mars are clearly unfavorable, at least on the surface—a cold, dry desert with hardly any atmosphere except for a little carbon dioxide. Probes landing on Mars have, however, confirmed that there is a considerable amount of frozen water at the poles. Additionally, there are many observable features of the kind expected from erosion by rivers or by surf at a seashore. This means that at some stage in the Martian past, there must have been a large amount of liquid water present—exactly what is needed for our kind of life to begin. During that early period the water would have formed an ocean. Initially this could have been several miles deep, with its center near what is now the Martian north pole.
So life could have originated at the edge of this ocean, way back in Martian history.
There are a couple of objections to this theory. One is that the atmosphere would not have contained oxygen. However, primitive life-forms on Earth are believed to have been been able to survive in an atmosphere that was also very deficient in oxygen, so that might not have mattered.