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21.
The Freja ultraviolet imager 总被引:2,自引:0,他引:2
J. S. Murphree R A. King T. Payne K. Smith D. Reid J. Adema B. Gordon R. Wlochowicz 《Space Science Reviews》1994,70(3-4):421-446
Auroral images acquired by satellite instrumentation have proven to be a crucial component of the scientific equiry into the physical processes of the Earth's magnetosphere. TheFreja mission provided an opportunity to extend these measurements into the temporal and spatial regime commonly associated with ground-based optical imagers. Employing the basic procedure used successfully in theViking program allowed image repetition rates of 6 s to be achieved with simultaneous exposure of all pixels within the field-of-view. Typical exposure times of 0.3 s required development of an improved image intensifier system and operational requirements resulted in image formats covering approximately one-third of a spin. Simultaneously exposing two broad-band UV cameras, the instrument generates in its normal operational mode 264.6 kbytes per image pair. Results from initial operations confirm the design approach and suggest such imagers can be routinely included on challenging low cost missions such asFreja. 相似文献
22.
M M Saulmon K F Reardon W Z Sadeh 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(1-2):289-292
As space missions become longer in duration, the need to recycle waste into useful compounds rises dramatically. This problem can be addressed by the development of Controlled Ecological Life Support Systems (CELSS) (i.e., Engineered Closed/Controlled Eco-Systems (ECCES)), consisting of human and plant modules. One of the waste streams leaving the human module is urine. In addition to the reclamation of water from urine, recovery of the nitrogen is important because it is an essential nutrient for the plant module. A 3-step biological process for the recycling of nitrogenous waste (urea) is proposed. A packed-bed bioreactor system for this purpose was modeled, and the issues of reaction step segregation, reactor type and volume, support particle size, and pressure drop were addressed. Based on minimization of volume, a bioreactor system consisting of a plug flow immobilized urease reactor, a completely mixed flow immobilized cell reactor to convert ammonia to nitrite, and a plug flow immobilized cell reactor to produce nitrate from nitrite is recommended. It is apparent that this 3-step bioprocess meets the requirements for space applications. 相似文献
23.
D O'Sullivan D Zhou E Semones W Heinrich E Flood 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(6):1420-1423
Particle intensity, dose equivalent and absorbed dose have been measured on board the space shuttle Endeavour during STS-108 in December 2001 by Dublin Institute for Advanced Studies (DIAS). The dose estimates are based on very accurate measurements of recoils produced in CR-39 by cosmic ray primary and secondary protons and heavier nuclei and by secondary neutrons. The corresponding LET spectra were used to determine dose equivalent and absorbed dose values. Estimates of the total flux of Z > or = 2 nuclei have been undertaken and a preliminary charge spectrum was measured. Some comparisons are made with preliminary data obtained on STS-105 (ISS Expedition) and other missions using CR-39 detectors. 相似文献
24.
W Trettnak W Gruber F Reininger P O'Leary I Klimant 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(4-5):139-148
The optical oxygen sensor is a novel device for the determination of oxygen in gases or dissolved in liquids. It is based on the measurement principle of fluorescence quenching, which is completely different from that of polarographic oxygen sensors (today the most widespread devices of oxygen detection). The new instrument offers features and advantages, which render it not only a realistic alternative, but, for specific applications, make it superior to existing electrochemical methods. The system is based on low-cost semiconductor devices (light-emitting diodes, photodiodes, low-cost analogue and digital components) and new LED-compatible oxygen-sensitive membranes. The flow cell of the instrument may be thermostatted and the sensor can be calibrated by a simple two-point calibration procedure. The optical oxygen sensor is particularly suitable for measuring dissolved oxygen in respirometry, since no oxygen is consumed by the device and the signal is independent of sample flowrate or stirring speed. Typical fields of application are monitoring of oxygen in ground and drinking water, in process control in bioreactors and in breath gas and blood gas analysis. 相似文献
25.
T W Tibbitts 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(4-5):197-201
The use of controlled environments is subject to problems from contaminants emitted from materials of the system and from plants. Many contaminants are difficult to identify because injurious dosages are very low, there is a lack of information on what compounds injure plants, because species and cultivars differ greatly in their sensitivity to injury and injury symptoms often are not distinctive. Plastics have been shown to emit many different volatile compounds. The compound, di-butyl phthalate, contained in certain flexible plastics, has been shown to be very toxic to plants. Other injuries have been produced by caulking compounds and bonded screening. Paints have been shown to release xylene that is toxic to plants. Steam for humidification can cause problems because of hydroxylamines and other compounds added to steam used for heating to control fungal growth in return lines. Mercury, from broken thermometers is a particular problem in growth chambers because small quantities can collect in cracks and slowly volatilize to slow growth of plants. Plants themselves release large quantities of volatile hydrocarbons, with ethylene being the commonly recognized chemical that can be damaging when allowed to accumulate. People release large quantities of carbon dioxide which can cause variations in the rate of growth of plants. Contaminant problems can be controlled through filtering of the air or ventilation with make-up air, however the potential for problems is always present and careful testing should be undertaken with the particular species and cultivars being grown insure that there are no toxic agents altering growth in each particular controlled environment being utilized. 相似文献
26.
P W Barlow 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,17(6-7):69-72
The origin and subsequent evolution of life on Earth has taken place within an environment of which a 1g gravitational force is a part. Thus, all living organisms accommodate this variable in their structure and function. Evolution has also selected mechanisms to sense gravity which, in consequence, give particular orientations to living process. It is anticipated that the higher the evolutionary status of an organism, the greater the chance that it will possess multiple mechanisms of gravisensing because evolution discards nothing that assists fitness, but only adds to existing processes. A multiplicity of mechanisms permits gravity to participate in a wide range of developmental programmes, such as taxes, morphisms and tropisms, through the action of different sensors and distinct transduction/response pathways. 相似文献
27.
F A Cucinotta L W Townsend J W Wilson M J Golightly M Weyland 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):661-670
The solar particle events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and linear energy transfer (LET) spectra in shielding discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup. 相似文献
28.
An electric vehicle (EV) energy management system (EMS) developed to accurately predict and extend the usable driving range and the life of the battery pack is discussed. The EMS monitors and records battery state of charge, vehicle performance, power consumption of key components, and driver's actions. Convenient drive inputs in conjunction with memorized energy consumption profiles allow accurate prediction of driving range and selection of appropriate recharging profiles. EV range extension is accomplished by identifying inefficient use of energy, resulting in EMS modification of energy usage by offending subsystems or EMS suggestion to the driver of improved driving habits or vehicle use. Factors affecting the accuracy of range prediction and the amount of range extension are described 相似文献
29.
The NASA Advanced Communications Technology Satellite (ACTS) program will conduct high-data-rate experiments that will be applicable to the emerging broadband services of the telephony market. The existing broadband integrated services digital network (BISDN) services and delivery method as defined by the International Consultative Committee for Telephone and Telegraph (CCITT) and satellites' role in provisioning those services are discussed. The ACTS experimental efforts are summarized 相似文献
30.
D. Koschny V. Dhiri K. Wirth J. Zender R. Solaz R. Hoofs R. Laureijs T.-M Ho B. Davidsson G. Schwehm 《Space Science Reviews》2007,128(1-4):167-188
ESA’s Rosetta mission was launched in March 2004 and is on its way to comet 67P/Churyumov-Gerasimenko, where it is scheduled
to arrive in summer 2014. It comprises a payload of 12 scientific instruments and a Lander. All instruments are provided by
Principal Investigators, which are responsible for their operations.
As for most ESA science missions, the ground segment of the mission consists of a Mission Operations Centre (MOC) and a Science
Operations Centre (SOC). While the MOC is responsible for all spacecraft-related aspects and the final uplink of all command
timelines to the spacecraft, the scientific operations of the instruments and the collection of the data and ingestion into
the Planetary Science Archive are coordinated by the SOC. This paper focuses on the tasks of the SOC and in particular on
the methodology and constraints to convert the scientific goals of the Rosetta mission to operational timelines. 相似文献