Mars Pathfinder: A new era of Mars exploration
By Gloria Chang
Life on Mars would be hostile, if not impossible. The average temperature is -63 degrees Celsius, plunging to
-120 at the polar ice caps. Dry dust storms rip through the deep canyons where water must have once flowed. Volcanic
rocks litter the red soil, coloured by the oxidized iron in the Martian rock. Despite these less-than-hospitable surroundings,
NASA's Mars Pathfinder will land on Mars on July 4th and herald a new era of Mars exploration.
To see a REALVIDEO panoramic view of Mars, click here.
"It's a new and much less expensive way," says Michael Carr of the U.S. Geological Survey in Menlo Park, California.
Priced at $150 million, the Mars Pathfinder is one twentieth the cost of the Viking - the last spacecraft to land on Mars
just over twenty years ago. Along with an orbiter called Mars Global Surveyor, Pathfinder is the first of a series of ten
smaller, less ambitious spacecraft headed in pairs for the Red Planet over the next decade. A pair of spacecraft will
bring back clues from Mars every 26 months in order to solve an ongoing mystery - is there or was there ever life on
Mars?
Since the turn of the century, we've been fascinated with the possibility of life on Mars. Fuzzy telescopic pictures of
Mars once showed deep river channels which some had interpreted to be canals of some sort. Later, many believed
that the planet's colour variation was caused by flourishing vegetation in the summer, which lay dormant in the winter.
Flybys of the planet in the sixties however, quashed any hope of life at the time. They indicated a heavily cratered
surface like our own moon - which of course harbours no life. Since then it's been a never-ending rollercoaster of
enthusiasm and waning interest for life on the Red Planet. But why this planet in particular?
"Mars is the only planet outside of the Earth that has all the ingredients you need to support life," says Dr. Matthew Golombek, project scientist for Pathfinder at the Jet Propulsion Lab in Pasadena, California. "It's also the only one where you could even imagine terraforming it - making it more earthlike."
Dry river valleys, deep canyons, flood features and signs of
water erosion suggested that early Mars was warm and wet. Mars was also dotted with volcanoes.
Viking pictures showed channels, volcanoes, canyons The
Viking landers, which carried complex life-detecting tests, produced negative results.
Still, interest soon picked up again when earth studies of a molecule found in all living organisms called ribonucleaic
acid (RNA) revealed an unexpected discovery. "The most primitive organisms on Earth - the ones that have evolved the
least from however life started - all lived in places where water comes into contact with volcanoes," explains
Carr, who led the imaging team. These hydro-thermal conditions were also abundant on Mars.
Hence, yet another spaceship was sent to Mars in 1992. But, days before the Mars Observer entered its orbit, NASA lost
contact with it. What arose from the $2 billion loss, was a whole new plan to explore Mars. Rather than placing all their
eggs into one basket, NASA now plans to send a series of smaller, inexpensive missions "so that over a period of time,
we would accumulate the kind of knowledge acquired from these large, expensive ones," explains Carr, who was also
on the review panel for the conception of Pathfinder.
As its name implies, Pathfinder will help blaze a new trail in the search for life - with American fanfare. To ensure it
lands on Mars on the American Independence Day, NASA increased Pathfinder's speed to make up for a two-day launch
delay last December.
As it stands, Pathfinder is expected to parachute into the mouth of a
large river channel called Ares Vallis on July 4th. Scientists hope to get a look at a wide variety of rocks there, which
they suspect would have been pushed down by a large flow of water. The channel drains into ancient terrain called the
highlands which are 3.6 billion years old. It's also the home of the well-known Mars meteorite ALH84001 that made
headlines last August when NASA scientists announced the rock showed evidence of past life on Mars.
Once it lands, the petals of
the spacecraft will unfold and let the first-ever rover on any planet to roam the landing site. Think of the rover -
dubbed Sojourner - as a little geologist, says Golombek. With an Alpha Proton X-Ray Spectrometer on its back,
it can analyze the composition of the Martian rocks and beam the information back to Earth. It will be given directions
from Earth by remote control.
In fact, the Mars Pathfinder won't definitively answer the question of life on Mars - at least not now.
"That's clearly the overriding question, but you need a whole variety of missions [about a dozen] to do that," says Golombek. "We need to look at Pathfinder as the first small step in that… we need to build up our database and our understanding about Mars to the point where you can then ask that all-important question at the right place." Golombek means that literally. Viking showed that life isn't ubiquitous on Mars, so now it's a matter of zeroing in on the right place before testing for life. A Mars rock sample - which would help squelch the controversy over microbial life - won't even be brought back to Earth until 2005.
"The Pathfinder was originally going to be mainly an engineering test to test the new ways of landing on Mars," says Carr, "because the Viking was so expensive." True to its name, the Mars Pathfinder will really just uncover the route that subsequent spacecraft will take.
Mars meteorite ALH84001
While nothing precludes either the lander or rover from lasting up to a year, it will be successful if they last a week. "Effectively, if we land safely and if we drive the rover off and operate for a week or so, I think we've been remarkably successful," says Golombek. But, the chances are if it lasts a week, it will last for months, adds Carr.
With a long and difficult history and years of study, does it matter if there's life on Mars?
"Isn't that almost a theological question?" asks Golombek. He goes on: "Are we alone in the universe? is really the question we're after here. You can stare up at the sky and the stars for millions of years… and you may never hear anything because the time delay between us and the next star is so huge. Dr. Matthew Golombek, project scientist for Mars Pathfinder
But here, we can go right next door in our solar system - our neighbouring planet - and see whether the development of life would happen anywhere where the conditions are right, or whether you need divine intervention. And to me that's well worth it." Click on Mars for a 4 1/2 minute NASA REALVIDEO of how Pathfinder works.
Watch for more stories and updates when EXN goes to Pasadena, California to cover the Mars Pathfinder landing.
For more on the science instruments on Mars Pathfinder, check out NASA's Mars Pathfinder Instrument Descriptions.
Also check out NASA's Mars Pathfinder Science Objectives.
All pictures courtesy NASA.
In 1976, the Viking missions seemed to confirm this. 55,000 pictures taken by two Viking orbiters which systematically
mapped Mars, showed that Mars had an abundance of the one key ingredient for life - water.
(river channels: signs of water on mars)
Slowing down from its travelling speed of 37,000 kilometres per hour, Pathfinder's landing will be cushioned by
enormous balloons. But, with gravity a third of what it is on Earth, Pathfinder will bounce up as high as a ten-storey
building until it finally settles onto the surface.
The analysis however, won't settle the controversy over the much-talked-about microbial life on ALH84001. "The pictures
from the meteorite have resolutions of nanometers - that's a billionth of a centimeter," explains Carr. "The resolution on
the Pathfinder cameras is one millimetre. When you're looking for microorganisms, it's hopeless.
Still, the mission is a difficult one, the landing being the hardest thing to accomplish. "It takes four minutes from when
we hit the atmosphere to bouncing for the first time on the surface," explains Golombek. "In between that time, a
hundred events have to occur with split-second timing."
He pauses.
"Wouldn't you like to know?"