The coming return of John Glenn to space highlights the differences between how the world looked to Americans in 1962 and how it looks to us in 1998.
In 1962, as the first American to orbit the globe, Glenn reflected on the delicate environmental balance that protects life on the pale blue planet from the harsh and forbidding black matte of stars.
"Each time around, I noticed a strange phenomenon. The stars shone steady as they neared the horizon. Then they dimmed for a bit. But the stars brightened again before actually setting. They appeared to be passing through a layer of haze about six to eight degrees above the earth and two degrees thick."
The haze that Glenn described was the thin line of atmosphere: oxygen to breathe, ozone to shield ultraviolet radiation, and carbon dioxide and methane to trap reflected heat. The gaseous stuff of life. But from orbit, even the Earth's atmosphere acts only as a semi-transparent window to the starlit sky.
For Glenn's first orbital flight the mission goal was to return safely. Now 30 years later, he will use space not just as 'the high ground' but as a working laboratory. Glenn and the other astronauts will be making the first run at space-manufacture for a product called aerogel. In the words of early Mercury astronauts 30 year ago, the mission will 'push the envelope' on how aerogel can be improved. If successful, the experiment returns not just more aerogel, but a fundamentally different kind of material, what might be called the first "astrogel."
Aerogel is a remarkable substance. It's the lightest known solid, so much akin to air that it's sometimes called "frozen smoke." Its insulating properties are nothing short of remarkable, protecting virtually anything from heat or cold. It was used by NASA to keep the Sojourner rover warm on the surface of Mars where night time temperatures plunge to -100 degrees. A single one-inch window pane of aerogel is equivalent to the insulation provided by 32 windows panes of glass (R-20 to R-32 insulation factors).
Truly, aerogel would make a perfect window except for one thing: it's not perfectly transparent. Aerogel made on Earth is permeated with tiny, irregular pores that make aerogel hard to see through. There is evidence that the irregularities are diminished when the substance is manufactured in weightless conditions. Hence the experiment on STS-95. Astronauts will actually manufacture some aerogel in orbit and see what happens. If aerogel could be made transparent it could revolutionize household windows. By some estimates, aerogel costs 3 times the price of glass, but glass manufacturing costs are only about 10% of the purchase price for windows, so aerogel window manufacturing might still carry a large profit margin.
Aerogel may also have a role to play in keeping the atmospheric line clear, the thin air gap that Glenn described more than 35 years ago. By reducing home heating costs aerogel could reduce global energy needs and minimize the pollutants that inevitably come with energy production. Science Magazine (1998) listed next-generation window technology as a critical point in the US obligations to meet its international global warming commitments prescribed by the late 1997 Kyoto Conference resolutions. The Kyoto Conference set international standards for a 5-10% cut in carbon budgets. This is considered impossible by some economists without triggering an economic recession. Under the agreement, carbon percentage allotments are proposed as tradable items and can be bought by industrialized countries from less industrialized societies, in effect a stock market trading on smog.
New technology could offer a way out. As an example, the December 1997 issue of Today's Homeowner magazine listed NASA aerogel research ("Super Stuff") in its cover story entitled "Best New Products for 1998." The article concludes: "The potential market for a clear aerogel is enormous, considering that window heat loss accounts for up to 30 percent of energy lost from a home. A well-designed aerogel window could lower heating and cooling costs by a comparable figure".
Reduced industrial waste is another long-term target of aerogel research. Not only is aerogel of scientific interest to reduce the energy load, but also to capture waste and polluting gases before they reach the atmosphere. The industrial group, The Attia Applied Science, Incorporated (TAASI), concluded in 1996: "The market for the aerogel absorbents is potentially vast. In principle, wherever alcohol and fossil fuels are used, aerogel absorbents could capture waste gases before they are emitted into the atmosphere."
In 1998, the scientific quest to reduce the haze continues, both with deeper environmental study and in some small part, a remarkable semi-transparent window insulator called aerogel. Glenn's flight will be the first attempt by space scientists to improve the transparency of aerogel and thus clear the view. During the STS-95 mission astronauts will test whether aerogel made in the weightlessness of space is more transparent than aerogel made here on Earth. As progress continues, the use of clear insulation betters the chances that over coming generations even the atmospheric haze will not cloud our views of the stars.