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The Webfooted Astronomer - May 2001


Minutes: Is the Mars Society Full of Hot Air?

By Greg Donohue

GENERAL announcements came at the end of the meeting, so let me start there before recapping the evening's presentation. The new SAS club brochures and flyers are available at the back desk at each general meeting. Brian Allen encourages group members to take some and distribute them to spread the word about SAS.

Bruce Weertman has made a contact that is interested in lighting codes for the city of Roslyn. See the Dark Skies Northwest Web site at The Telescope Maker's group will meet on May 5, the first Saturday in May.

Sending a Solar Montgolfiere Balloon to Mars

George Best introduced the evening's guest speaker, Chris Vancil, a member of the Mars Society's Seattle chapter Chris is currently head of the Mars Society's Mars Balloon Engineering and Science Mission. The Purpose of the Mars Society is "to further the goal of the exploration and settlement of the Red Planet." Or, as Chris puts it more succinctly, "... to promote people going to Mars."

Why go to Mars? Mars is relatively close and is the next most habitable planet in our solar system. Establishing a permanent human presence there is possible. But only two countries, the U.S. and the former Soviet Union, have sent probes to Mars. The Japanese have a mission scheduled for 2004. But one of the big reasons is the possibility of finding life on the Red Planet. Such a find would be, in and of itself, one of the turning points in human history. We wouldn't have to find little green men on Mars to change our perception of mankind's place in the cosmos, just little green algae....

As evidence for possible life on Mars, Chris mentioned the infamous Alan Hill rock (Mars meteorite ALH84001, which contained structures that could be interpreted as fossils of microscopic life). In February of this year, scientists claimed that uniquely shaped magnetite crystals found in the Alan Hill rock provide further evidence of past microscopic life on Mars. But why send people when we have cute little robots? Consider the Sojourner rover, carried aboard the Mars Pathfinder mission. Sojourner was on the surface of Mars for about six weeks, and captured the attention of the world. But a human geologist on site could probably have obtained the same information in half an hour, and placed the information in context.

Mars is currently a cold and dry place, some believe that in the past, Mars might have been warm and wet, and far more hospitable to life. And while the Red planet has little atmospheric water currently, there is still enough of it to create a body of water about the size of Lake Washington. Subsurface water might also be trapped in lava tubes; after all, Olympus Mons is the largest shield volcano in the solar system.

The Mars Society is actively doing things to prepare for a manned mission to the red planet and a permanent human presence on Mars. A human habitat on Mars is likely to be a large, squat cylindrical-shaped structure. The Mars Society has built and is testing a similar structure, called the Flashline Mars Arctic Research Station (

Other projects include "hitchhiker" payloads, where small pieces of equipment are included as part of other missions. An example would be the Mars Microphone aboard the Mars Polar Lander, which was lost (whether through a crash or simple communications failure is still unclear). An improved version of the Mars Microphone is now planned for redeployment aboard the French NetLander mission in 2007.

These hitchhiker projects are patterned after the highly successful OSCAR (Orbiting Satellites Carry Amateur Radio) missions. Ham radio operators sent some 40 amateur radio payloads into orbit, including AMSAT (OSCAR 7). These payloads piggybacked on other missions by replacing some of the ballast needed for the primary missions' cargoes.

The Mars Balloon project, which Chris heads, is working on sending a Montgolfiere (hot air) solar/infrared balloon to the fourth planet. Launched atop an Ariane V rocket, the probe would arrive at Mars with a delta-V of 1.5 km/sec.

From the late 1970s through the early 1990s, the French Space Agency conducted over 30 missions involving solar/infrared-heated Montgolfiere balloons. Flying at about 35 kilometers altitude (where the air pressure is roughly equivalent to that on the Martian surface), all the missions were conducted over the Arctic, because such balloons require very cold outside air temperatures. The longest mission lasted 69 days and circled the Earth twice.

The Mars Society's Mars Balloon would utilize this type of solar/infrared technology. During the day, the balloon uses energy from the Sun to heat its internal lifting gas to around 80 degrees C, while the outside temperature would be -70 to -80 degrees C. At night, the balloon would gently drop to the Martian surface, perhaps dragging a tail of instruments to take readings of various kinds. Chris guesses that the cost of the balloon itself (not including launch) would be $6 million./p NASA's Jet Propulsion Laboratory (JPL) is also working on balloons to explore Mars. Information on their Planetary Aerobot Program can be found at

Balloons have already been used successfully to explore Venus' atmosphere. In 1985, as part of a joint Russian, French, and American effort, two Venus Vega super-pressure balloons were released in the atmosphere, and returned valuable data over the course of nearly two days. While not the same type as those envisioned for use on Mars, the Venus Vega balloons still show the value of balloons in planetary exploration.

Manned missions to Mars have been envisioned in two basic varieties. One is the "90-day" plan. This would entail a big spacecraft, with all the fuel necessary to get to Mars and back. Such a mission would pass by Venus first, dropping two probes into its atmosphere. This type of mission is estimated to cost about $450 billion, and would only allow about two weeks on the Martian surface—a seemingly small return on a rather large investment.

The other type of mission, known as "Mars Direct," would take 6 to 9 months of travel time, and would only carry enough fuel to get from Earth to Mars. An advance unmanned spacecraft would be sent ahead, land on Mars, and make fuel for the return trip by extracting the necessary elements from the Martian environment. Only when the fuel-making station had signaled that it had successfully generated the required fuel would the manned part of the mission be launched. Mars Direct would cost only $10 billion (less than the Apollo program), and allow humans to explore the surface of Mars for a full year and a half, giving us a much larger bang for the buck.

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