J.2.2 Space debris flux models
J.2.2.1. MASTER-2005 space debris model
J.2.2.1.1 Overview
MASTER-2005 (referred to in 10.2.3) uses a semideterministic approach which represents the debris environment by modelling its history from the beginning of spaceflight to present [RD.88]. It considers all known source terms (launch and mission related objects, break-ups, solid rocket motor firings, release of reactor coolant during reactor core ejection by RORSAT satellites, paint flakes, ejecta and Westford needles) for the debris population and follows the orbital evolutions of the resulting particles. MASTER-2005 implements the Divine-Staubach meteoroid model [RD.108] and the seasonal meteoroid stream models from Jenniskens-McBride (see Annex C) and Cour-Palais.
The space debris population at the reference epoch (May 1st, 2005) is derived from 203 on-orbit break-ups, 16 RORSAT reactor core ejections and 1 076 solid rocket motor firings.
MASTER-2005 covers impactor sizes larger than 1μm for Earth-bound target orbits up to geostationary altitudes. An analysis application allows interrogating the spatial debris distribution to determine collision fluxes for an arbitrary target orbit passing through the control volume. Flux results can be analysed with respect to collision velocity magnitude, its direction (azimuth and elevation), the orbit location, and the 3D position where the flux was encountered.
MASTER-2005 is provided on a DVD containing the flux database together with the analysis software and runs on all Windows and Unix as well as Linux operating systems.
J.2.2.1.2 Access points
The MASTER-2005 DVD can be obtained through:
ESA Space Debris Office, ESA/ESOC
Robert-Bosch-Str.
5, D-64293
Patches can be obtained through http://www.master-2005.de/
J.2.2.1.3 Impact velocity for space debris
Impact velocities can range from 0 to about 15,5 km s-1 with an average velocity of 10 km s-1 for low inclination and of 13 km s-1 for high inclination orbits.
J.2.2.1.4 Mass density of space debris objects
The mass density of space debris objects is a function of the object diameter and the space debris sources considered. Different sources release particles of different materials the density of which can vary between 0,01 – 4,7 g cm-3. Since different source terms dominate in different size regimes, the cumulative density averaged over all objects varies significantly with the limiting diameter. For example, objects larger than 1cm are mainly explosion fragments so that the average density of debris is close to that of aluminium (2,7 g cm-3). Objects larger than 1 μm are dominated by solid rocket motor dust (aluminium oxide, 3,5 g cm-3).
J.2.2.2. Other space debris models
J.2.2.2.1 Overview
Several additional space debris models exist for various ranges of applicability and different purpose. Only a subset of these is publicly available and thus of interest for this standard.
For
some international space programmes specific models, other than MASTER-2005,
have been defined as applicable. For the International Space Station the space
debris models NASA-90
[RD.21] or ORDEM-2000 [RD.107] are applicable, even for European contributions.
J.2.2.2.2 ORDEM-2000
ORDEM 2000 was developed by the NASA Orbital Debris Program Office at JSC [RD.107]. It uses careful empirical estimates of the orbit populations derived from measurements, incorporating a large set of observational data with the US Space Command Catalog, the Haystack Radar, and the Long Duration Exposure Facility spacecraft returned surfaces being the three primary sources. By this, the model covers an object size range from 10 µm to 10 m and employs a new analytical technique utilizing a maximum likelihood estimator to convert observations into debris population probability distribution functions.
The model describes the orbital debris environment in the low Earth orbit region between 200 and 2,000 km altitude.
J.2.2.2.3
NASA-90 model
From about 1990 until 1996 the NASA space debris engineering model defined in [RD.21] has been most widely used for design applications. This model is given in terms of simple analytical expressions. It is relatively easy to use and widely distributed. However, it has some known shortcomings of which the assumption of spherical orbits for all debris particles is probably the most severe. The user should be aware of its shortcomings.