Search

A key element of the President's Vision for Space Exploration is the development of a new space transportation system to replace Shuttle that will enable manned exploration of the moon, Mars, and beyond. NASA has tasked the Constellation Program with the development of this architecture, which includes the Ares launch vehicle and Orion manned spacecraft. The Orion spacecraft must carry six astronauts and its primary structure should be reusable, if practical. These requirements led the Constellation Program to consider a baseline land landing on return to earth. To assess the landing system options for Orion, a review of current operational parachute landing systems such as those used for the F-111 escape module and the Soyuz is performed. In particular, landing systems with airbags and retrorockets that would enable reusability of the Orion capsule are investigated. In addition, Apollo tests and analyses conducted in the 1960's for both water and land landings are reviewed. Finally, tests and dynamic finite element simulations to understand land landings for the Orion spacecraft are also presented.

Currently available launch vehicles cannot support logistically the human exploration of the Moon and Mars in the next century. They are too small and too expensive for this job. Past studies have shown that the costs of programs leading to the acquisition and operation of extraterrestrial bases are driven by the space transportation system, which accounts for about two-thirds of total program costs. Consequently, more emphasis has to be placed on the question of the next-generation launch vehicles to be developed. This paper attempts to define the problem at hand and to give an overview of the options and trends to be expected. The issues of expendable versus reusable, as well as small versus heavy lift launchers are discussed. Specific transportation costs for low Earth orbit as well as high-energy missions are presented for selected space transportation system concepts.

Human exploration of the solar system can be said to have begun with the Apollo missions. The Apollo Project was publicly funded with the narrow technical objective of landing human beings on the Moon. The transportation and life support systems were specialized technical designs, developed in a project management environment tailored to that objective. Most scenarios for future human exploration assume a similar long-term commitment of public funds to a narrowly focused project managed by a large, monolithic organization. Advocates of human exploration of space have not yet been successful in generating the political momentum required to initiate such a project to return to the Moon or to explore Mars. Alternative scenarios of exploration may relax some or all of the parameters of organizational complexity, great expense, narrow technical focus, required public funding, and control by a single organization. Development of the Moon using private investment is quite possibly a necessary condition for alternative scenarios to succeed.

Many of the launch systems that are used by the United States to send payloads to orbit trace their heritage to military systems of the 1950s and 1960s. Even with launch systems built on more recent technology, the cost of placing a payload in orbit is thousands of dollars per pound. To develop new customers with heretofore only dreamed-of missions—tourism in space, power from the moon, etc.—the cost of placing a payload in orbit must be reduced by an order of magnitude or more. Since the propulsion system is the cornerstone of a space transportation system, it has a major impact on the acquisition and operations costs. Improvements in materials and in manufacturing technology are needed to develop lightweight, high-strength materials for efficient and economic structures, thermal protection systems, tanks, etc. Operational considerations, such as fewer vehicle elements to check out and to integrate, have a significant impact on lowering launch costs and should be given strong consideration in the choice ...

Passive base vibration-control systems for reducing the transfer of orbiter vibration energy to its payload during liftoff are studied. The launch vehicle payload is modeled as a nonuniform flexible structure, and its sensitive subsystem is treated as a single-degree-of-freedom system. Two modified designs for trunnions are suggested for the vibration-control system. These modified trunnions make use of rubber bearings with and without trunnion friction. The performance of these base vibration control systems for protecting the Space Shuttle payload and its sensitive subsystem during liftoff is evaluated. A sinusoidal excitation and the Space Transportation System mission 41 (STS-41) \iZ-direction liftoff acceleration are used as dynamic input of the orbiter. Effects of the trunnion friction and flexibility on the vibration of payload and its subsystem are studied, and the results are compared with those in the absence of the base vibration-control systems.

The orbital recovery of the external tank (ET), backbone of the U.S. space transportation system, can be considered enormously important for the future development and colonization of space. America’s ability to respond to the many space opportunities on the horizon of research, commercialization, and planetary science depend on the resiliency of the space transportation system, and especially on the use of the external tank in space. The use of ETs—as launch stages for planetary exploration, as large platforms in either low Earth orbit or geosynchronous Earth orbit to coorbit with other payloads requiring human interaction, or as an element of support for the next part of space station Freedom—could be of fundamental importance. The purpose of this paper is to describe a method for the orbital construction of the device and the corresponding recovery of the ET.

Modular assembly in low Earth orbit (MALEO) is a new strategy for building an initial operational-capability lunar habitation base, the main purpose of which is to safely initiate and sustain early lunar base buildup operations. In this strategy the lunar base components are brought up to low Earth orbit (LEO) by the Space Transportation System (STS), and assembled there to form the complete lunar base. Specially designed propulsion systems are then used to transport the MALEO lunar base, complete and intact, all the way to the moon. Upon touchdown on the lunar surface, the MALEO lunar habitation base is operational. The strategy is unlike conventional concepts, which have suggested that the components of the lunar base be launched separately from the Earth and landed one at a time on the moon, where they are assembled by robots and astronauts in extravehicular activity (EVA). The architectural drivers for the MALEO concept are, first, the need to provide an assured safe haven and comfortable working environment for the astronaut crew as safely and as quickly as possible, with the minimum initially risky EVA, and secondly, the maximum exploitation of the evolutionary benefits derived from the assembly and operation of space station Freedom (SSF-1). Commonality and inheritability from the space station assembly experience is expected to have an advantageous impact on both the space station program as well as the MALEO lunar base.