Space vehicles

A theme that has come to the fore in advanced planning for long-range space exploration is the concept of "propellantless propulsion" or "field propulsion." One version of this concept involves the projected possibility that empty space itself (the quantum vacuum, or space-time metric) might be manipulated so as to provide energy/thrust for future space vehicles. Although such a proposal has a certain science-fiction quality about it, modern theory describes the vacuum as a polarizable medium that sustains energetic quantum fluctuations. Thus the possibility that matter/vacuum interactions might be engineered for space-flight applications is not a priori ruled out, although certain constraints need to be acknowledged. The structure and implications of such a far-reaching hypothesis are considered herein. Comment: Paper withdrawn. Author Ibison does not subscribe to some of the speculations in this document

Abstract. The microwave thermal thruster heats propellant via a heat-exchanger then expands it through a rocket nozzle to produce thrust. The heat-exchanger is simply a microwave-absorbent structure through which propellant flows in small channels. Nuclear thermal thrusters are based on an analogous principle, using neutrons rather than microwaves, and have experimentally demonstrated specific impulses exceeding 850 seconds. A microwave equivalent will likely have a similar specific impulse, since both nuclear and microwave thermal thrusters are ultimately constrained by material thermal limits, rather than the energy-density limits of chemical propellants. We present the microwave thermal thruster concept by characterizing a novel variation for beamed-energy launch. In reducing the thruster concept to practice, the enabling physical process is microwave absorption by refractory materials, and we examine semiconductor and susceptor-based approaches to achieving this absorption withi...

Since the STS-114 mission in August of 2005, the FAA has partnered with NASA to protect aircraft flying in the National Airspace System from the potential hazards associated with a catastrophic failure of a reentering Space Shuttle orbiter, similar to that which occurred during ...

A theme that has come to the fore in advanced planning for long-range space exploration is the concept of "propellantless propulsion" or "field propulsion." One version of this concept involves the projected possibility that empty space itself (the quantum vacuum, or space-time metric) might be manipulated so as to provide energy/thrust for future space vehicles. Although such a proposal has a certain science-fiction quality about it, modern theory describes the vacuum as a polarizable medium that sustains energetic quantum fluctuations. Thus the possibility that matter/vacuum interactions might be engineered for space-flight applications is not a priori ruled out, although certain constraints need to be acknowledged. The structure and implications of such a far-reaching hypothesis are considered herein.

A general relativistic scenario is utilized to build a non-perturbative model, in Schwarzschild metric, for the rep- resentation of observed angles among star pairs. This model is then applied to an end-to-end simulation of the GAIA satel- lite, a concept for global astrometry within the 2000+ scientific program of the European Space Agency. GAIA is expected to measure positions, parallaxes, and annual proper motions to better than 20 arcsec for more than 50 million stars brighter than V'16 mag. This first attempt at modeling global astromet- ric data within the framework of general relativity considers a static sphere, namely, only Schwarzschild azimuth and colati- tude are estimated, locating stars on the Schwarzschild sphere centered at the Sun. The results show that measurements of large arcs among stars, each measurement good to 100arcsec (as expected for V' 16 mag stars), repeated over an observing pe- riod of only one year can be modeled to yield 20 arcsec errors on...

The first satellite Sputnik came about in 1957, the law regulating activities in outer space came in a decade later. The law was then dynamic and evolved to fulfill the changing needs of the world. Quite unfortunately, it stopped evolving a decade later. The stagnation has cost dearly as the following slides would reveal.

The SuperNova / Acceleration Probe (SNAP) is a space-based experiment to measure the expansion history of the Universe and study both its dark energy and the dark matter. The experiment is motivated by the startling discovery that the expansion of the Universe is accelerating. A 0.7 square-degree imager comprised of 36 large format fully-depleted n-type CCD's sharing a focal plane with 36 HgCdTe detectors forms the heart of SNAP, allowing discovery and lightcurve measurements simultaneously for many supernovae. The imager and a high-efficiency low-resolution integral field spectrograph are coupled to a 2-m three mirror anastigmat wide-field telescope, which will be placed in a high-earth orbit. The SNAP mission can obtain high-signal-to-noise calibrated light-curves and spectra for over 2000 Type Ia supernovae at redshifts between z=0.1 and 1.7. The resulting data set can not only determine the amount of dark energy with high precision, but test the nature of the dark energy by examining its equation of state. In particular, dark energy due to a cosmological constant can be differentiated from alternatives such as "quintessence", by measuring the dark energy's equation of state to an accuracy of +/-0.05, and by studying its time dependence.

Structural health monitoring (SHM) is certainly one of the key technologies required to achieve the goal for new space vehicles of having reduced maintenance costs with increased levels of safety. For the time being, sensor technology has reached a good technology readiness level, but the integration of these technologies into the design process of a space vehicle has not received much consideration. The present article aims at giving a reference about the existing technologies on the matter and an introduction to some of the key issues for the integration of a SHM system into the design process of future space vehicles. In addition, the accident that occurred to the space shuttle Columbia is analyzed in order to show how SHM could be effective for the improvement of safety in future space vehicles. Furthermore, since important changes to aeronautical design procedures have been introduced as a consequence of catastrophic events, the evolution of aeronautical design practices in parallel with accidents has been examined.