An overview of RADOM results for earth and moon radiation environment on Chandrayaan-1 satellite

The RADiatiOn Monitor (RADOM) is a miniature dosimeter-spectrometer that flew onboard the Chandrayaan-1 lunar mission in order to monitor the local radiation environment. Primary objective of the RADOM experiment was to measure the total absorbed dose, flux of surrounding energetic particles and spectrum of the deposited energy from high energy particles both en-route and in lunar orbit. RADOM was the first experiment to be switched on after the launch of Chandrayaan-1 and was operational until the end of the mission. This paper summarizes the observations carried out by RADOM during the entire life time (22 October 2008–31 August 2009) of the Chandrayaan-1 mission and compares the measurement by RADOM with the radiation belt models such as AP-8, AE-8 and CRRESS.     

The Magnetospheric Multiscale Magnetometers

The success of the Magnetospheric Multiscale mission depends on the accurate measurement of the magnetic field on all four spacecraft. To ensure this success, two independently designed and built fluxgate magnetometers were developed, avoiding single-point failures. The magnetometers were dubbed the digital fluxgate (DFG), which uses an ASIC implementation and was supplied by the Space Research Institute of the Austrian Academy of Sciences and the analogue magnetometer (AFG) with a more traditional circuit board design supplied by the University of California, Los Angeles. A stringent magnetic cleanliness program was executed under the supervision of the Johns Hopkins University’s Applied Physics Laboratory. To achieve mission objectives, the calibration determined on the ground will be refined in space to ensure all eight magnetometers are precisely inter-calibrated. Near real-time data plays a key role in the transmission of high-resolution observations stored on board so rapid processing of the low-resolution data is required. This article describes these instruments, the magnetic cleanliness program, and the instrument pre-launch calibrations, the planned in-flight calibration program, and the information flow that provides the data on the rapid time scale needed for mission success.     

Effects of space flight on surface marker expression.

Space flight has been shown to affect expression of several cell surface markers. These markers play important roles in regulation of immune responses, including CD4 and CD8. The studies have involved flight of experimental animals and humans followed by analysis of tissue samples (blood in humans, rats and monkeys, spleen, thymus, lymph nodes and bone marrow in rodents). The degree and direction of the changes induced by space flight have been determined by the conditions of the flight. Also, there may be compartmentalization of the response of surface markers to space flight, with differences in the response of cells isolated from blood and local immune tissue. The same type of compartmentalization was also observed with cell adhesion molecules (integrins). In this case, the expression of integrins from lymph node cells differed from that of splenocytes isolated from rats immediately after space flight. Cell culture studies have indicated that there may be an inhibition in conversion of a precursor cell line to cells exhibiting mature macrophage characteristics after space flight, however, these experiments were limited as a result of technical difficulties. In general, it is clear that space flight results in alterations of cell surface markers. The biological significance of these changes remains to be established.     

Some Electrical/Electronic Areas Requiring Emphasis in Preparation for Future Space Programs

A panel session held at the 1965 Aerospace Conference, Houston,Tex., June 23, 1965. Panelists discussed Life-Suppport interfaces with Electric Power; Communications; Navigation; System Integration for Future Space Programs; and Reliability.     

Design and Application of an Adaptive Tracking Filter Control System

The design of an adaptive tracking filter control system and its application to large flexible booster vehicles is described. The problem of elastic vehicle stability is considered along with its solution by conventional and adaptive techniques. The improvement in vehicle stability, which may be achieved with the adaptive tracking filter technique as compared to conventional techniques, is shown. The control system evolved uses two adaptive tracking filters to phase stabilize the first and second bending modes, in addition to conventional compensation techniques. The application of this adaptive technique to a vehicle in which the modal frequencies are in close proximity (<2.5 percent separation) is discussed. The mechanization of the adaptive control system involves the selection of design techniques and components that are electrically and physically compatible with the intended airborne application. The development of a suitable frequency tracking technique and tracking filter is described, in addition to the electronic and mechanical design of the adaptive control system prototype.     

Acceleration of the High Speed Solar Wind in Coronal Holes

We outline a theory for the origin and acceleration of the fast solar wind as a consequence of network microflares releasing a spectrum of high frequency Alfvén waves which heat (by cyclotron absorption) the corona close to the Sun. The significant features of our model of the fast wind are that the acceleration is rapid with the sonic point at around two solar radii, the proton temperatures are high (~ 5 million degrees) and the minor ions are correspondingly hotter, roughly in proportion to their mass. Moreover we argue that since the energy flux needed to power the quiet corona in closed field regions is about the same as that needed to drive the fast solar wind, and also because at deeper levels (< 2 × 10⁵ K) there is no great difference in the properties of supergranules and network in closed and open field regions, the heating process (i.e., dissipation of high frequency waves) must be the same in both cases. This revised version was published online in June 2006 with corrections to the Cover Date.     

Coronal Heating: a Comparison of Ion-cyclotron and Gravity Damping Models

SOHO/UVCS data indicate that minor ions in the corona are heated more than hydrogen, and that coronal heating results in T_⊥ larger than T_‖. Analogous behavior has been known from in situ measurements in solar wind for many years. Here we compare and contrast two mechanisms which have been proposed to account for the above behavior: ion-cyclotron resonance and gravity damping. This revised version was published online in June 2006 with corrections to the Cover Date.     

Single ion actions: the induction of micronuclei in V79 cells exposed to individual protons.

Understanding the effects of single-particles from conventional radiation biology experiments is problematic due to the stochastics of particle tracks. This complicates the determinations of risk associated with low doses. We have developed a charged particle microbeam, which allows individually counted particles to be delivered to precise cellular locations. The system is capable of delivering a single charged particle with > 99% efficiency. Of these particles 90% are delivered with a resolution of +/- 2 micrometers and 96% with a resolution of +/- 5 micrometers. We have carried out preliminary studies in Chinese hamster V79 cells to monitor the effectiveness of low energy protons at inducing cytological damage. We have used the micronucleus assay as a measure of predominantly lethal chromosome damage. The effects of a single 3.2 MeV proton delivered individually to cells could be measured, with less than 2% of the exposed cells producing micronuclei 24 hours later. The yield of micronuclei formation was essentially linear up to the highest dose (30 particles per cell nucleus) delivered. Ultimately, the ability to target particles to different parts of the cell nucleus may start to impact on models available for chromosome aberration formation and chromosomal Organisation and mechanisms underlying genomic instability.