Dynamic considerations for control of closed life support systems

Reliability of closed life support systems will depend on their ability to continue supplying the crew's needs in the face of perturbations and equipment failures. These dynamic considerations interact with the basic static (equilibrium) design through the sizing of storages, the specification of excess capacities in processors, and the choice of system initial state (total mass in the system). This paper uses a very simple system flow model to examine the possibilities for system failures even when there is sufficient storage to buffer the immediate effects of the perturbation. Two control schemes are shown which have different dynamic consequences in response to component failures.     

Advanced regenerative environmental control and life support systems: Air and water regeneration

Extended manned space missions will require regenerative life support techniques. Past U.S. manned missions used nonregenerative expendables, except for a molecular sieve-based carbon dioxide removal system aboard Skylab. The resupply penalties associated with expendables becomes prohibitive as crew size and mission duration increase. The U.S. Space Station, scheduled to be operational in the 1990's, is based on a crew of four to sixteen and a resupply period of 90 days or greater. It will be the first major spacecraft to employ regenerable techniques for life support. The paper uses the requirements for the Space Station to address these techniques.     

New multifrequency measurements of the spectrum of the cosmic background radiation

New measurements of the Cosmic Background Radiation temperature at 12 cm, 6.3 cm, 3 cm, 0.9 cm and 0.3 cm have made in July 1982 from the White Mountain High Altitude Research Station. The results are presented and the existence of spectral distortions discussed.     

On the levels of enzymatic substrate specificity: implications for the early evolution of metabolic pathways.

The most frequently invoked explanation for the origin of metabolic pathways is the retrograde evolution hypothesis. In contrast, according to the so-called "patchwork" theory, metabolism evolved by the recruitment of relatively inefficient small enzymes of broad specificity that could react with a wide range of chemically related substrates. In this paper it is argued that both sequence comparisons and experimental results on enzyme substrate specificity support the patchwork assembly theory. The available evidence supports previous suggestions that gene duplication events followed by a gradual neoDarwinian accumulation of mutations and other minute genetic changes lead to the narrowing and modification of enzyme function in at least some primordial metabolic pathways.     

Lunar habitat concept employing the space shuttle external tank

The space shuttle external tank, which consists of a liquid oxygen tank, an intertank structure, and a liquid hydrogen tank, is an expendable structure used for approximately 8.5 min during each launch. A concept for outfitting the liquid oxygen tank-intertank unit for a 12-person lunar habitat is described. The concept utilizes existing structures and openings for both man and equipment access without compromising the structural integrity of the tank. Living quarters, instrumentation, environmental control and life support, thermal control, and propulsion systems are installed at Space Station Freedom. The unmanned habitat is then transported to low lunar orbit and autonomously soft landed on the lunar surface. Design studies indicate that this concept is feasible by the year 2000 with concurrent development of a space transfer vehicle and manned cargo lander for crew changeover and resupply.     

Cosmic-ray intensity variations in the 3-dimensional heliosphere

The study of cosmic-ray intensity variations have been carried out with data registered by ground-based and balloon-borne equipment for the past 50 years or more. The International Geophysical Year (IGY) from July 1957 to December 1958 gave an impetus to global collaborations. A world-wide network of concerted measurements became available with the advent of the space age.In situ measurements by satellite-borne detectors led to deep-space exploration. The spacecraft Pioneers and Voyagers, during the past 15 years, traversing farther out into the heliosphere at increasing radial distances from the sun have changed the study of time variations into one of time and spatial variations.Furthermore, with the Voyager 1, proceeding asymptotically towards heliolatitudes of 35° north since its encounter with Saturn and the anticipated direction of Voyager 2 after its encounter with Neptune in late-1989 towards 48° south heliolatitude, is converting the study into a truly three-dimensional exploration of the heliosphere. Thus, the investigation of galactic cosmic-ray intensity variations fromin situ measurements deep in the heliosphere in distance, latitude, and over solar cycles is indeed a remarkable achievement.The various cosmic-ray intensity variations over different time-scales, the modulation of the intensity by the evolving solar activity and the role of the electromagnetic state of the interplanetary medium (otherwise called heliosphere) can now be investigated as never before; these studies contribute immensely to our knowledge of the solar neighbourhood. This article essentially deals with the studies of time and spatial variations of cosmic-ray intensity that have been conducted especially over the past two decades.     

Study of shaping strategies for blisk vane channels by a cup tool

This paper deals with roughing milling of vane channels for axial blisks by a cup tool. The effect of the shaping strategy on waviness of the surfaces being machined and allowance for subsequent operations is determined.     

Two magnetars: SGR 1627–41 and 1E 1547–5408

We describe the results obtained with Target of Opportunity observations of the galactic sources SGR 1627–41 and 1E 1547–5408. These two transients show several similarities supporting the interpretation of Anomalous X-ray Pulsars and Soft Gamma-ray Repeaters as a single class of strongly magnetized neutron stars.     

Displacement simulation for spacecraft structure

The paper presents a technique of forming and evaluating the allowable clearance between a launch vehicle fairing and spacecraft.