Space medicine comes down to Earth

Over the years innovative technologies developed for space flight have found their way into a variety of useful terrestrial applications. Significant examples can be found in the area of space medicine, which has greatly influenced human health care delivery on Earth. This report discusses several US applications of space medicine to terrestrial health needs and services, stressing the importance of a ‘space applications mentality’ as a valuable national asset.     

High-velocity impact experiments needed to improve our understanding of the asteroids

The lifetime of almost all the asteroids against catastrophic impact events is less than the age of the solar system, implying that the asteroids can be considered as outcomes of catastrophic collisions. Therefore to understand their physical properties (structure, shape, rotation, regolith development) and their family memberships (since families are generated by the escape of breakup fragments), a systematic knowledge of the outcomes of catastrophic impacts under a variety of conditions seems needed. In particular, interesting fields to be explored by laboratory experiments are: the dependence of the critical energy densities associated with various degrees of fragmentation on the target's size and composition; the velocity distribution of the fragments and the inelasticity of the process in different cases; the shape of the fragments and its possible correlation with other quantities; the way a dust- or regolith-covered target affects the collisional outcomes; the angular momentum partitioning and the rotation of the fragments. On this latter problem very few experimental results are presently available; on the other hand, the rotation of small asteroids presents several intriguing “anomalies”.

A significant progress of our understanding of asteroid collisional evolution and related phenomena can be provided by new laboratory experiments of collisional breakup. The targets should have spherical and/or irregular shape (up to axial ratios of the order of 2), and should be made of (possibly different) geological materials. The interesting projectile velocities are of the order of the relative velocities commonly found among asteroids, i.e., in the range 1 to 10 Kms⁻¹. In order to get catastrophic collisions, the ratio of the projectile kinetic energy to the target mass (≡E/M) has to be chosen within a “critical” range (for basalt targets, from 10⁶ to 10⁸ erg/g). In some particular cases, this kind of experiments has been already performed in past (Gault and Wedekind [10]; Fujiwara et al. [7]; Fujiwara and Tsukamoto [9]); however the generalization of the results to a wide range of experimental conditions is lacking, and many problems of outstanding importance to model asteroid evolution are still completely open.     

The telemedicine frontier: going the extra mile

Telemedicine has the potential to have a greater impact on the future of medicine than any other modality and will profoundly alter the medical landscape of the twenty-first century. In the most remote areas, it can bring high-quality health care where none is now available. In global health care, it can enhance and standardize the quality of medical care, including developing countries. In the realm of space flight, it can provide a lifeline to medical expertise and monitoring. Through its mobility, it can provide urgently needed health care in instances of natural disaster. However, a number of challenges exist in its coordination and implementation on a global scale, specifically in the international and remote disaster scenarios. In the area of spaceflight, telemedicine capability will remain a consultation/information ‘lifeline’, but additional onboard medical capability and expertise will become crucial complements as missions become more advanced and remote from Earth.     

Mathematical modeling and experimental investigations of oxygen-methane fuel combustion at coaxial-jet supply into the combustion chamber of liquid-propellant rocket engine

The numerical results are presented for the case of coaxial-jet supply at the different ratio of mass component velocities at the combustion chamber inlet with the constant and variable relationship of oxygen-methane components. The experimental investigations of coaxial-jet mixing elements as part of the model setup chamber operating on corrosive producer gas and gaseous methane were carried out. A qualitative pattern of the $ overline {rho u} $ overline {rho u} parameter influence on the chamber economic feasibility was obtained: as $ overline {rho u} $ overline {rho u} decreases, the combustion efficiency coefficient grows.     

Experimental investigations of quasistable radiation belts formed after solar proton events in September–October 1989 and March 1991 based on measurements made by “Liulin” dosimeter-radiometer on board the “MIR” space station

Since 1988 high sensitivity dosimeter-radiometer “Liulin” has been installed on board the MIR space station. Device measured absorbed dose rate and flux of penetrating particles. Results of measurements showed that after powerful solar proton events (SPE) September–October, 1989 and March, 1991 additional quasistable radiation belts were formed in the near earth space within the interval L=1.8−3.0. These “new” belts were observed as an additional maximums in flux (and sometimes dose) channels when crossing the SAA region. “New” belts were quasi stable and existed at least several months, decaying slightly after SPE. Dose to flux ratio analysis showed that major components of these belts were energetic electrons and protons arising in connection with preceding SPEs.     

Calculation of resultant vector and principal moment of light pressure forces acting upon the spacecraft with a solar sail

Two methods of calculating the resultant vector and principal moment of light pressure forces, having an effect on a spacecraft with a composite solar sail, are compared. The first method is based on analytical formulas obtained without regard to shading of some parts of the sail by others. The second method uses a detailed geometrical model of the sail, which allows one to take such shading into account. Some part of photons falling on a sail is supposed to be reflected from it in a mirror manner, while the others are completely absorbed. The range of variation of sail orientation parameters with respect to incident solar light streams, where the first method turns out to be accurate enough, is found.     

Spectral analysis of ionospheric disturbances in the phase delay and radio signal amplitude at limb paths according to the <Emphasis Type="Italic">COSMIC</Emphasis> data in periods of solar activity

Based on more than 4500 sessions of radio transillumination of Earth’s atmosphere along the satellite–atmosphere–satellite path obtained in the COSMIC experiment, the distribution along latitude and over local time of the spatial spectra of variations in the ionospheric phase delay and signal amplitude has been analyzed. The spatial spectra have been calculated for two height ranges, i.e., 60–80 and 80–100 km. In the phase signal spectrum within the height range 80–100 km, the second maximum in the vicinity of a frequency of 7–8 rad/km is clearly seen. Its diurnal and latitudinal behavior and its decrease towards high latitudes in both hemispheres can also be seen. In the height range of 60–80 km, this maximum is hardly observed. Although solar flares can lead to substantial local changes in the electron concentration, no substantial difference in the behavior of the spectral densities of the amplitude and phase delay at long limb paths was observed within these two height ranges on days of active and quiet sun. The latter fact makes it possible to develop a united algorithm of optimal ionospheric correction of the radio occultation data independent of solar activity.     

Space-time structure of ion-cyclotron waves in the topside ionosphere as observed onboard the <Emphasis Type="Italic">ST</Emphasis>-<Emphasis Type="Italic">5</Emphasis> satellites

Results of observations of ion-cyclotron (IC) waves onboard the ST-5 satellites in the topside ionosphere (heights from a few hundred up to thousands of km) are presented. In this project, three identical micro-satellites were located during three months in 2006 in almost identical orbits with distances between them from first thousands to hundreds of km. All ion-cyclotron wave packets detected by two-three probes were observed at crossing one and the same latitude, which manifests their narrow localization in latitude with a characteristic scale from the first tens to 100 km. In no event IC waves were recorded with comparable amplitudes by all three satellites. At the same time, in the case of ST-5 flight near the ground-based induction magnetometer, a long emission in the same frequency range on the ground corresponded to a burst of IC waves in the topside ionosphere. This can indicate to the fact that an IC instability develops not continuously, but in the pulsing regime with a characteristic time of up to ∼10 min. A change in the rotation direction when a satellite crosses the wave structure is a characteristic feature of the polarization structure of registered transverse waves. The detected effects are discussed from the point of view of the existing models of generation and waveguide propagation of IC waves.     

Analytical Results for a Kalman Tracker Using Position and Rate Measurements

Analytical results are presented for determining the steady-state components of the gain and error covariance matrices of the two-state Kalman tracking filter with white noise maneuver capability.