Moon Base Now!

Space.com; Mar. 13, 2001; Science/Astronomy: "Forgotten Moons: Phobos and Deimos Eat Mars' Celebrity Dust"

Mysterious Deimos!  NASA/Viking

Take it from Arizona State University's Philip Christensen: "There is no object in the solar system that is not worth studying, but those moons suffer from being so close to such an interesting planet, and they've always taken a back seat."  He was talking about Mar's much neglected potato-shaped moons: Phobos and Deimos.  

Not much is known about these satellites.  The basic question: were they created when Mars formed or are they captured asteroids? -- is old and still unanswered.  In an era with probes imaging objects throughout the reaches of the solar system, the few close-up images of the moons were taken by Mariner 9 and the Viking Orbiter spacecraft in the 70's -- followed a quarter-century later by the Mars Global Surveyor.  That long drought would have been cut short if the Soviet Phobos lander had not mysteriously disappeared in the late 80's. Considering all the probes sent to Mars you can sense Christensen's frustration.  

Christensen is not the only one concerned about the Martian moons.  Fred Singer, president of the Science & Environmental Policy Project, advocates a manned landing on Deimos -- the smaller of the moons.  Orbiting at 20,000-km from the surface (compared to 378,000-km for our Moon), the more distant of the two Martian moons has an average diameter of 13-km.  The small size allows a surface gravity less than a tenth-percent of Earth's.  This makes human landing and departure from Deimos a lot less ambitious than the same task on Mars. 

Using the moon as a shield against cosmic rays and solar storms, astronauts on Deimos could send probes down to Mars.  These probes could be controlled in real-time due to proximity of the surface.  Research would start with sending a few probes down and using those results to determine the landing sites and missions of the next set of probes.  

Mysterious Phobos!  NASA/Viking

Cost is the advantage a Deimos base has over the much ballyhooed proposals for a manned landing on Mars.  Think of the cost of building a human lander and return vehicle to travel through the Mars atmosphere and gravity well.  There is also the task of constructing a shielded Mars base.  From Deimos small human teams could be dispatched to Mars for short periods if need be.  Singer points to the recent landing of the NEAR probe on Eros: "Phobos and Deimos are much easier to get to than Eros, and much easier to land on."

Christensen agrees that humans on a Martian moon would be a boon to understanding their origin.  "There's nothing like being out there with a hammer and a hand lens and doing real geology, being able to pick up the rock and look at it," he says.

Let's not wait too long to investigate these objects.  Phobos, a 23-km wide object, is very close to Mars with an orbit just 6,000-km from the surface -- and is spiraling into the planet at 1.8-meters every 100 year.  Phobos is therefore a temporary satellite of Mars that will crash into the planet in another 50-million years.  Another possibility is that gravitational forces will tear the moon apart and create a ring around the planet.  Either way, the Phobos crater crash site on the surface or ring around the planet, will sure attract future observers and perhaps put Deimos in the "back seat" again.

Percival Lowell: Off By a Few Billion Years

Reuters Newswire; Mar. 15, 2001; Washington: "Mars Calamity May Have Created Conditions for Life" 

SUNY Buffalo; Mar. 12, 2001; Press Release: "Mars' Volcanoes May Have Melted Ice, Producing Water Necessary for 'Life'" on Red Planet"

Olympus Mons -- the largest known volcano in the solar system -- resides on Tharsis. At 21-km tall it covers an area the size of Arizona.  NASA/Viking image.

Visual observations by Percival Lowell in the early part of the 20th century popularized the notion of Mars as a planet crisscrossed with water canals.  Observations with later and larger instruments did not detect these features and wide-field images from visiting space probes revealed volcanoes -- not water basins -- to be one of the most interesting feature of the planet.  Almost a hundred years after Lowell wrote about his ideas our knowledge of that planet continues to mature.  This has led to a correlation emerging between flowing surface water and volcanoes on Mars.  

A report in the journal Science by Roger Phillips, director of Washington University's (St. Louis) McDonnell Center for Space Sciences, proposes that volcanic activity on Mars resulted in a greenhouse effect that allowed water to flow on the surface.  This volcanic activity occurred when Mars was still young: from 3.8 billion to 3.5 billion years ago.  Intriguingly this warm and wet environment existed around the time that life-signs are purported to have formed in the famous Martian meteorite ALH84001.  

Phillips does not imply that his research proves life must have arisen on the Red planet: "It does imply that liquid water was available for life if the other factors were favorable."  But those few hundred million years of volcanic activity created a "brief, shining moment" for Mars.

His theory stems from analysis of gravitational and topographical data from the Mars Global Surveyor that is currently orbiting the planet.  The data indicate that Mars is a lumpy planet.  One side is dominated by a North American size region called the Tharsis rise, while the opposite side has the Arabia bulge.  These geographic features are believed to have arisen from extremely massive volcanism due to volcanoes on the Tharsis rise.

Water and carbon dioxide from Tharsis created an atmospheric greenhouse that warmed the surface.  Water fell to the surface and carved out valley networks that resembled Earth's river systems.  Enough volcanic gasses were released to submerge Mars under 400-feet of water -- though much of the gasses were actually lost to space.

This brief period in Mars history ended when the volcanoes stopped replenishing the greenhouse gasses.  Factors such as low-gravity and solar particles stripped away the atmosphere and any remaining ground water would have frozen (See NewNotes 01.01.01: Attracted to That Ol' Martian Magnetism).  Evidence for this frozen water is revealed in the study of other volcanoes on Mars.

"... these volcanoes have the largest and greatest numbers of channels associated with them, indicating that there was a lot of water around when they were forming ..."
-- Tracy Gregg, State University of New York at Buffalo

University at Buffalo geologists Tracy Gregg studied Mars Global Surveyor data related to two of the oldest volcanoes on Mars: Tyrrhena Patera and Hadriaca Patera are both in the southern hemisphere of the planet.  These volcanoes were active for 3.5-billion years and may still be  She is proposing that their volcanism caused frozen ground-water to flow again on Mars. 

"Of all the volcanoes on Mars, these volcanoes have the largest and greatest numbers of channels associated with them, indicating that there was a lot of water around when they were forming, though there doesn't appear to be any around now," said Gregg. 

Her proposal is that heat energy from the volcanoes melted ice in the ground.  Over the years the downhill flow of water away from the top of the volcano carved channels.  Gregg notes that the combination of heat energy, flowing water, and various chemicals spewing from the volcano could have made conditions ripe for life to have formed.  These results were presented at  the 32nd Lunar Planetary Science Conference at SUNY Buffalo.

Lowell's fanciful observations and interpretation of canals on Mars, at the beginning of the 20th century, led to popular belief of Mars as a dying planet who's inhabitant were redistributing scarce water across its surface.  Theories of flowing water and life on Mars ebbed after the first few probes reached the planet in the 60's and 70's -- and so did popular interest in the planet.  At the start of the 21st century the "tide has turned" and discussions of Mars again intrigue the popular audience with theories of  water and life.