The Causes Of Spacecraft Anomalies

To understand where best to focus efforts to improve our ability to prevent spacecraft anomalies, it is useful to examine compilations of spacecraft anomalies and to understand the space environment effects that cause them. The components of the space environment that can pose hazards to normal spacecraft operations include micrometeoroid and orbital debris which cause impact damage and increased contamination the neutral thermosphere which causes surface erosion due to atomic oxygen, satellite...

Ionospheric variability in the context of HF propagation

Figure 2 shows the maximum usable frequency (MUF) measured by an IRIS oblique ionosonde Arthur et al., 1997 on a 400 km path from Inskip (53.9 N, 2.8 W) to Malvern (52.1 N, 2.3 W), in the UK, over a period of 13 days in October 2002. This period coincided with a period of variable geomagnetic activity. The selected oblique ionograms from the data sets were examined and the MUF of the F layer trace was extracted using IRIS analysis software Heaton, 1999 . Figure 3 shows the minimum and maximum...

Inflight Measurements

Continued and improving monitoring of the environment is obviously important for improving knowledge of the environment, but also for providing the resources to respond to emerging requirements and for use in new analysis methods. ESA has successfully promoted the idea of having standard radiation environment monitors (SREMs) on as many missions as possible. These both contribute to the general body of data and provide mission-specific data, which can be used in real-time for protection, or...

Technological Developments

The future picture of aircraft operations, whether civil or military, is of one comprising a global multi-network infrastructure that provides for future growth, but ensures safety and security. It will have a satellite-based, air space management system with global connectivity, offering better C3I, free-flight routing for commercial aircraft and complete space-to-mud situational awareness for multi-national military operations. Combined with information technology, airspace and aircraft...

References

Aarons, J., Global morphology of ionospheric scintillation, Proc. IEEE, 70 (4), 360-377, 1982. Anderson, D.N., J.M.Forbes, and M. Codrescu, A Fully Analytical, Low- and Middle- Latitude Ionospheric Model, Journal of Geophysical Research, 94, 1520, 1989. Angling, M.J., and P.S. Cannon, Assimilation of Radio Occultation Measurements into Background Ionospheric Models, Submitted to Radio Science, 2003. Angling, M.J., P.S. Cannon, N.C. Davies, T.J. Willink, V. Jodalen, and B. Lundborg, Measurements...

Microsatellites and Facilities for InOrbit Experimentation

Lack of rapid, frequent and cheap access to space for technology experiments is a serious impediment to technology progress, both for assessing space environmental effects on systems, and in other areas. Microsatellites and nanosatellites offer relatively low-cost access to space for technology flight experiments and are often ideal for experiments related to environmental effects and as platforms for monitoring the environment in important regimes. This has been recognised by those...

Introduction

The ionosphere, an area of the atmosphere which extends from 80 to 1000 km, can significantly affect the propagation of radio frequency (RF) signals which pass through it or are reflected by it Cannon, 1994a Cannon, 1994b . The effects are varied but include absorption, refraction, retardation and scintillation. At frequencies above 1 MHz, the lower D region causes absorption and the higher E and F regions cause a variety of other effects. These effects, which include refraction, signal group...