Mars Balloons Reference Work
The Mars Aerobot/Balloon System (MABS) program built upon the technology advances from previous aerobot/balloon concepts. In the mid 1980’s, the Soviets and the French began collaborating on a Mars Aerostat mission set to depart in 1994. The Soviets planned to put two spacecraft in orbit around Mars, which would release landers and balloons to gather data on the Martian surface to send back to the orbiters, which would in the meantime make their own observations from space. “Mars 94” came to include more than 20 countries, which included the former Soviet bloc nations, France, Germany, Japan, the United Kingdom, and the United States.
The French CNES contributed a 66-foot-tall two-part Mylar balloon: the top portion was expected to be filled with helium and the bottom was going to be filled with Martian atmosphere. By day, the sun-heated Martian air expands so that the entire balloon would rise into the atmosphere to an altitude between 2-4 km, traveling hundreds of kilometers on the Martian winds. A camera carried in a gondola below would take high-resolution pictures of the Martian surface and transmit them to the Soviet Mars orbiters as well as to the American orbiter Mars Observer, which in turn would send them to Earth. CNES also provided the Mars Relay radio system to support the transmission of the data from the balloons and surface instruments to the orbiters.
At nightfall, the lower portion of the balloon would shrink with the falling temperature, bringing the entire balloon to the Martian surface, although the helium-filled portion would keep the balloon from completely sinking. A package of instruments attached to a dangling snake-like add-on would reach the ground, take measurements of surface phenomena and transmit these data to the Soviet orbiters and to the American orbiter Mars Observer.
The next day, the balloon would rise again and travel hundreds of kilometers further to obtain more pictures. This day-night cycle would occur 10 times before too much helium leaks out for the balloon to stay above Mars’ surface; over that time, the balloon would have traveled approximately 1500 km.
However, with the collapse of the Soviet Union, the mission was further delayed from 1994 to 1996. Further delays pushed the launch to 1998. However, this would have meant the mission would reach Mars during winter, increasing the likelihood of the balloon being destroyed in high winds. Eventually, the mission was cancelled.
The 1996 mission no longer included the French balloons; however, the French continued their own balloon program. They developed the “balloon family” described below:
- The zero pressure stratosphere balloons are the ones that flew for the shortest duration, staying aloft for a period of days, but carrying up to 3 tons of payload and flying as high as 40 km. Filled with helium, the balloons expanded as they rose and the surrounding atmospheric pressure grew lower, until the gas completely filled the balloons. With nightfall, the helium volume reduced and the balloons sank. These were the largest balloons.
- The InfraRed Montgolfiere (MIR) balloons carried much smaller payloads (up to 50 kg) but flew for weeks, by day or night. The MIR flew higher during each day, heated by the Sun, and lower with each successive night, but held up by infrared radiation reflected from the Earth’s surface; this up-and-down pattern enabled study of different levels of the stratosphere.
- Atmospheric Boundary Layer Pressurized Balloons flew much lower, at a maximum altitude of 1-2 km, studying the planetary boundary layer characteristics (i.e., pressure, temperature, humidity, and wind). These “superpressure” balloons flew for months at a time with the air density remaining constant around them; they were sealed so that their volume stayed constant even as outside temperature and pressure varied. These balloons were smaller so they carried much smaller payloads, around the order of a few kg.
- The Aeroclipper studied the interactions of the atmosphere and the ocean, making measurements of these two environments at the same time. This balloon floated over the ocean’s surface in the direction of the wind, but more slowly; a guide rope hanging down to the ocean’s surface had a gondola attached near the top that studied the atmosphere, and a probe to study the ocean was secured to the bottom of the rope. The Aeroclipper was capable of traveling weeks at a time.
Several types of payloads were used on the balloons. One notable payload was SPIRALE, which used infrared laser spectroscopy to measure high-troposphere-lower-stratosphere molecular species: carbon monoxide, carbon dioxide, triatomic oxygen, nitrogen dioxide, nitrous oxide, nitric oxide, hydrochloric acid, nitric acid, methane, hydrogen peroxide, hypochlorous acid, and carbonyl fluoride.
Another balloon-borne payload, SALOMON, was a UV-visible detecting spectrometer that measured trace molecular species in the stratosphere at night, using the Moon as a light source. These conditions were the best for measuring ozone, nitrogen dioxide, nitrogen trioxide, aerosols, and bromine dioxide that are useful for example for studying ozone depletion.