Scientists Hope Balloon Will Fly--Even Past Mars

An international team of scientists will soon journey to southern France where the first passengers were carried aloft 205 years ago in a lighter-than-air flying machine.

The scientists will unfurl a large, paper-thin balloon, and if luck is with them, they will bring about the marriage of the fanciful art of ballooning with Space Age technology.

But their contraption will not carry a sheep, a duck and a rooster. That was the passenger manifest for the historic flight of Sept. 19, 1783. Instead, it will carry the dreams of a small band of scientists who expect to explore Mars--if only vicariously--with balloons.

The program has been endorsed officially by the Soviet Union, which will carry at least one French balloon to Mars in 1994 aboard an unmanned Soviet spacecraft and release it into the Martian atmosphere. The balloon will be designed to drop down to the planet’s surface during the cool of the evening for close-up study of the ground and then lift up as the atmosphere warms the following morning and move on to a new location, traveling wherever the wind blows.

“We have told the Soviets we are ready to go,” Jacques Blamont, a leading scientist with the French space agency, said during a recent interview.

Extensive Tests Completed

But it has taken the combined efforts of scientists, balloonists and space enthusiasts on three continents to reach that point. Extensive tests have been carried out in Southern California’s Mojave Desert by the Pasadena-based Planetary Society, which has served as a catalyst and adviser to French and Soviet scientists. The Mars balloon will be built by the French space agency and a prototype will be flown in France this week.

Some scientists find the concept attractive because it could permit them to study details of a wide area of Mars by transporting their instruments over much greater distances than even the most sophisticated automated rover could travel on the ground. Others find beauty in the simplicity of the scheme--balloons would be autonomous, using the planet’s atmosphere as the primary means of locomotion. But some fear failure because balloons on Mars would have to operate unattended in an environment that is not well understood, and they would have to be built out of such lightweight materials that the project poses extreme technological challenges.

It can be done, insists world-class balloonist Tom Heinsheimer of Los Angeles, who has served as an adviser to both the Soviets and the French.

“But it’s a new kind of flying machine that nobody’s ever built before,” he said.

Arden Albee, dean of graduate studies at Caltech and an expert on Mars, believes the “concept makes sense, but it has an element of risk” because the balloon must be extremely lightweight yet strong enough to survive in the atmosphere of Mars.

“It’s an innovative way to get data that there’s just no other way to get,” Albee said.

The Mars program will build on the earlier success of two balloons released into the atmosphere of Venus in 1985 by Soviet spacecraft on their way to Halley’s comet. Blamont, who served for several years as a consultant to the Jet Propulsion Laboratory, helped design those balloons. For two days the balloons were blown by 150-m.p.h. winds 33 miles above the furnace-like surface of Venus, traveling nearly a third of the way around the planet and collecting enormous amounts of scientific data on its atmosphere.

However, the objectives of the mission to Mars will be far more demanding, and even key Soviet scientists have not found it easy to convince their colleagues of the wisdom of the plan.

During a recent meeting in Moscow, one top Soviet scientist said he was having trouble winning support because the whole idea seemed foreign to space scientists.

‘They Don’t Know Balloon’

“They never deal with anything like that,” the scientist said of his co-workers. “They know rover. They know orbiter. They don’t know balloon.”

In an effort to bridge that gap, the Planetary Society recently conducted a series of extraordinary balloon flights over Lithuania in the western part of the Soviet Union. A balloon and gondola was shipped from Southern California to Lithuania by the society, accompanied by 17 persons who completed nine flights over the rural countryside.

Lou Friedman, executive director of the society, said the Soviets placed no restrictions on where the flights could be carried out.

“It was amazing,” added Heinsheimer, still puzzling over the freedom that the Southern California balloonists enjoyed. “We would just drive along, pick out a field and get out the balloon and fly it.”

Several Soviet scientists made some of the flights, Friedman said.

At one point the balloon crossed a river, descended out of the sky and landed near a startled cow. Moments later a young boy from a nearby farm approached the Americans and spoke fluent English. He was followed by an elderly woman. The boy asked about the balloon and quickly relayed the information to the old woman, who in turn began holding forth for other Lithuanians who rushed over from nearby farms.

Invited to Dinner

Later, the old woman invited the Americans into her home for dinner.

All of the flights were filmed, both from the ground and the air, while balloon pilots Ed Johnson, Doug Hughes and Shirley Smith took turns at the controls. The freedom to film the operation amazed the balloonists because aerial photographs--including snapshots from the window of a commercial airliner--are normally prohibited throughout the Soviet Union.

The Planetary Society, which has served mainly as a catalyst for the Mars balloon program, is now carrying out a series of tests in the Mojave Desert and will decide soon whether it will seek a formal role in the Soviet project, or back off and leave the rest to the French.

In a sense, it is appropriate that the first Mars balloons should come from France, where ballooning was born in the 18th Century. The first balloon, launched on June 5, 1783, was 23,430 cubic feet in size. It measured 105 feet in circumference.

The Mars balloon will be about four times that size.

“By space standards, it is very large,” Blamont said, although many recreational balloons are much larger.

What will set it apart, however, are the weight restrictions that the French must meet if they are to get their balloon aboard a spacecraft.

‘Like Cigarette Paper’

The skin of the balloon will have to be so thin that it will be “like cigarette paper,” Blamont said. “No balloon has ever been that thin.”

But it will have to be strong enough to withstand 100-m.p.h. winds while lugging around a payload of 50 to 60 pounds in temperatures that vary wildly from more than 200 degrees below zero Fahrenheit to 70 degrees above.

Although those conditions would destroy a balloon on Earth, the air on Mars is so thin that the atmospheric pressure on the ground is less than 1% of that on Earth. That gives hope to the scientists that their balloon might be able to withstand the sandstorms that at times blanket the entire planet.

Four different types of balloons are under study. The goal is to build a balloon that will descend low enough for its instruments to rest on the surface at night while they collect data on soil composition and surface features--but not so low that the balloon itself is likely to get snagged on the rugged countryside.

One innovative proposal is to have two balloons, one suspended above the other. The upper balloon would be inflated with gas as soon as it is released from the spacecraft. Suspended below that would be a thermal balloon with a hole in the bottom. As the atmosphere warms up in the morning, the thermal balloon would expand, lifting the entire assembly. Later in the day, as the atmosphere cooled, the thermal balloon would deflate, allowing the instruments to reach the ground.

Experimental ‘Snake’

The Planetary Society team has experimented with a “snake” that would dangle from the bottom of the balloon. The snake would contain the instruments that would be needed on the surface of Mars, along with power sources and heaters to keep them from freezing. As the balloon descends, the snake acts as ballast. When enough of the snake is on the ground, the balloon will descend no farther, waiting until the next day’s sun to warm the air, causing it to rise and move on to the next location.

Meanwhile, the instruments will have spent the night collecting data on the surface.

At that point, the U.S. National Aeronautics and Space Administration will get into the act. NASA expects to launch its Mars observer satellite to the red planet in 1992. Thus it should be in orbit around Mars when the Soviet spacecraft arrives there two years later.

An agreement has been reached between the two superpowers for the U.S. spacecraft to act as a communications link between the Soviet Union and the Soviet Mars probe--including the balloons.

That is expected to greatly increase the amount of data that the Soviets will be able to recover from their mission.

Blamont was in the United States recently to help work out the details for that cooperative effort.

“This is real,” he said of the communications project.

So is the balloon program, but most scientists who are involved in it concede there is considerable risk that it will fail, because no one has tried anything quite like it before.

Heinsheimer, who has flown balloons all over the world, believes it is worth a try, and he thinks he might even know what to expect on Mars.

“I’ve crashed in Death Valley,” he said. “I know Mars.”