To open wide the doors to space development, a new generation of space transportation systems is required. The objective is to provide inexpensive and reliable access to space. An early goal is lowering the cost of placing a pound of payload into Earth orbit from $10,000 to $1,000. And NASA has set a goal to cut space transportation costs by the year 2015 to one percent of today's costs.

Taking on these challenging assignments is the Marshall Space Flight Center in Huntsville, Alabama. The center is NASA's premier organization for developing space transportation and propulsion systems, and for conducting microgravity research. Marshall is NASA's Center of Excellence for space propulsion.

Marshall's Space Transportation Programs Office is developing and demonstrating key, critical technologies to significantly reduce the cost of space transportation. Marshall and industry partners are moving forward on the X-33 program, an effort to demonstrate the key design and operational aspects of a single-stage-to-orbit Reusable Launch Vehicle (RLV) rocket system. Teamwork between government and industry is reducing the risk to the private sector in developing a commercially viable RLV system. In one area of work, the X-33 system is to demonstrate aircraft-like operational attributes, characteristics mandatory to lowering the expense of reaching space.

A second RLV program is the X-34, a reusable technology demonstrator vehicle. The X-34's fast-track development is leading to a vehicle that flies at eight times the speed of sound and reaches an altitude of 250,000 feet. Marshall is providing design and development of the X-34's main propulsion system, the Fastrac engine.

The first test flights of the X-34 will begin in late 1998, and X-33 flights are slated for mid-1999.

Earth-to-orbit transportation demands highly reusable systems. Marshall's Advanced Reusable Technologies project is pursuing high strength, lightweight structures and cryogenic propellant tanks, durable thermal protection systems, automated checkout and health monitoring of RLV systems, and long-life propulsion components.

Looking even further into the future, Marshall is studying numerous advanced space transportation concepts and technologies. Among these: Air-breathing and pulse-detonation rocket engines and a solar thermal upper stage that uses the Sun's light to produce thrust. Exciting uses of space tethers may one day include generating electrical power for spacecraft, link orbiting satellites to travel in formation, boost satellites to higher orbit, or trail research instruments in the atmosphere.

As stated in the NASA Strategic Plan, "the Human Exploration and Development of Space (HEDS) Enterprise will contribute new scientific knowledge by studying the effects of gravity and the space environment on important biological, chemical, and physical processes. This knowledge will provide fundamental insights for new Earth-bound applications and technology."

Within the NASA HEDS Enterprise, Marshall Space Flight Center's Microgravity Research Program is leading the nation in furthering the development of the space frontier by investigating the fundamental physical, chemical, and biological effects of the microgravity environment of space. Also, the Microgravity Research Program's Space Product and Development Office partners with industry and universities to foster the commercial development of space. Combustion processes are being investigated, as are ways to use microgravity to assess phase changes--when a material changes from one phase--liquid, solid, or gas--to another.

Fluid physics, for instance, is the study of the motion of fluids and the effects of such motion. Since three of the four stages of matter (gas, liquid, and plasma) are fluid, even the fourth, solid, behaves like a fluid under many conditions. Fluid physics is vital, therefore, to understanding, controlling, and improving all of our industrial, as well as natural processes. A low-gravity environment provides scientists near ideal conditions to probe flow phenomena otherwise too complex to study on Earth.

Biotechnology is one discipline that is playing an increasingly important role in medical research and the development of pharmaceutical drugs, agricultural research and products, and environmental protection. Major areas of inquiry in this discipline are fundamental to biotechnology science, such as protein crystal growth, and cell and tissue culturing.

A protein crystal growth program has been created to learn how protein crystals grow in space and how to optimize the growth process, while producing large, high-quality crystals of selected proteins. Microgravity conditions inside an orbiting spacecraft, such as the Space Shuttle and the future International Space Station, are relatively free from the gravitational effects of sedimentation and convection. This state of constant free-fall is ideal for studying the mysterious process of crystal growth--what conditions lead to the best crystals and how crystals grow. Improved understanding of the molecular structures and interactions of proteins are important clues that drug designers can utilize to develop new drug treatments that target specific human, animal, and plant diseases. Protein crystal growth experiments and the hardware to investigate crystal growth have both been led by teams of Marshall scientists.

The Microgravity Research Program's work on a bioreactor offers wisdom into how cells endeavor to form complex organisms. Such knowledge is key to understanding the chemistry and mechanics of healthy organs and of cancers, infectious diseases, immune system failures, and other public health problems.

Invented by NASA, the rotating bioreactor spins a fluid medium filled with cells. The spin of the device neutralizes most of gravity's effects and encourages cells to grow in a natural manner. As cells replicate, they "self-associate" to form a complex matrix of collagens, proteins, fibers, and other chemicals. Three-dimensional tissue specimens approximating natural growth are yielded by the bioreactor. These samples provide the opportunity to study the complex order of tissue in a culture system that can be manipulated by drugs, hormones, and genetic engineering. However, the constant force of gravity here on Earth mechanically limits the size of tissue constructs made in the bioreactor. Early tests of the bioreactor aboard Space Shuttle missions and on Russia's Mir space station point to the growth of much larger, more complex tissue masses than those obtainable in ground-based NASA bioreactors.

Imagine a 21st century future where a space business park is conducting the business of producing made-in-space medicines, speciality glass, and unique electronic components. The first settlements in space, medical research facilities, stop-over tourism hotels--this is a vision attainable by microgravity research carried out today, and work presently in progress to build affordable, reliable, and safe space transportation to open the "Highway to Space."