NASA Scientific and Technical Aerospace Reports - The University ...

20100017731 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, USA
Low-Cost Propellant Launch to Earth Orbit from a Tethered Balloon
Wilcox, Brian H.; March 4, 2006; 17 pp.; In English; IEEE Aerospace Conference, 4 Mar. 2006, Big Sky, MT, USA; Original
contains black and white illustrations; Copyright; Avail.: Other Sources
ONLINE: http://hdl.handle.net/2014/41563
Propellant will be more than 85% of the mass that needs to be lofted into Low Earth Orbit (LEO) in the planned program
of Exploration of the Moon, Mars, and beyond. This paper describes a possible means for launching thousands of tons of
propellant per year into LEO at a cost 15 to 30 times less than the current launch cost per kilogram. The basic idea is to
mass-produce very simple, small and relatively low-performance rockets at a cost per kilogram comparable to automobiles,
instead of the ~25X greater cost that is customary for current launch vehicles that are produced in small quantities and which
are manufactured with performance near the limits of what is possible. These small, simple rockets can reach orbit because
they are launched above ~95% of the atmosphere, where the drag losses even on a small rocket are acceptable, and because
they can be launched nearly horizontally with very simple guidance based primarily on spin-stabilization. Launching above
most of the atmosphere is accomplished by winching the rocket up a tether to a balloon. A fuel depot in equatorial orbit passes
over the launch site on every orbit (approximately every 90 minutes). One or more rockets can be launched each time the fuel
depot passes overhead, so the launch rate can be any multiple of 6000 small rockets per year, a number that is sufficient to
reap the benefits of mass production.
Author
Tethered Balloons; Propellants; Low Earth Orbits; Launch Costs; Spin Stabilization; Low Cost
16
SPACE TRANSPORTATION AND SAFETY
Includes passenger and cargo space transportation, e.g., shuttle operations; and space rescue techniques. For related information see
also 03 Air Transportation and Safety; 15 Launch Vehicles and Launch Operations; and 18 Spacecraft Design, Testing and Performance.
For space suits see 54 Man/System Technology and Life Support.
20100017223 NASA Johnson Space Center, Houston, TX, USA
Modeling of LEO Orbital Debris Populations in Centimeter and Millimeter Size Regimes
Xu, Y.-L.; Hill, . M.; Horstman, M.; Krisko, P. H.; Liou, J.-C.; Matney, M.; Stansbery, E. G.; [2010]; 1 pp.; In English; 61st
International Astronautical Congress, 27 Sep. - 1 Oct. 2010, Prague, Czech Republic
Report No.(s): JSC-CN-20066; Copyright; Avail.: Other Sources; Abstract Only
The building of the NASA Orbital Debris Engineering Model, whether ORDEM2000 or its recently updated version
ORDEM2010, uses as its foundation a number of model debris populations, each truncated at a minimum object-size ranging
from 10 micron to 1 m. This paper discusses the development of the ORDEM2010 model debris populations in LEO (low
Earth orbit), focusing on centimeter (smaller than 10 cm) and millimeter size regimes. Primary data sets used in the statistical
derivation of the cm- and mm-size model populations are from the Haystack radar operated in a staring mode. Unlike
cataloged objects of sizes greater than approximately 10 cm, ground-based radars monitor smaller-size debris only in a
statistical manner instead of tracking every piece. The mono-static Haystack radar can detect debris as small as approximately
5 mm at moderate LEO altitudes. Estimation of millimeter debris populations (for objects smaller than approximately 6 mm)
rests largely on Goldstone radar measurements. The bi-static Goldstone radar can detect 2- to 3-mm objects. The modeling
of the cm- and mm-debris populations follows the general approach to developing other ORDEM2010-required model
populations for various components and types of debris. It relies on appropriate reference populations to provide necessary
prior information on the orbital structures and other important characteristics of the debris objects. NASA’s LEO-to-GEO
Environment Debris (LEGEND) model is capable of furnishing such reference populations in the desired size range. A
Bayesian statistical inference process, commonly adopted in ORDEM2010 model-population derivations, changes a priori
distribution into a posteriori distribution and thus refines the reference populations in terms of data. This paper describes key
elements and major steps in the statistical derivations of the cm- and mm-size debris populations and presents results. Due to
lack of data for near 1-mm sizes, the model populations of 1- to 3.16-mm objects are an empirical extension from larger debris.
The extension takes into account the results of micro-debris (from 10 micron to 1 mm) population modeling that is based on
shuttle impact data, in the hope of making a smooth transition between micron and millimeter size regimes. This paper also
includes a brief discussion on issues and potential future work concerning the analysis and interpretation of Goldstone radar
data.
Author
Earth Orbital Environments; Space Debris; Models; Low Earth Orbits
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