Carbon dioxide removal system for closed loop atmosphere revitalization,candidate sorbents screening and test results

Due to the difficulty and expense it costs to resupply manned-spacecraft habitats, a goal is to create a closed loop atmosphere revitalization system, in which precious commodities such as oxygen, carbon dioxide, and water are continuously recycled. Our aim is to test other sorbents for their capacity for future spacecraft missions, such as on the Orion spacecraft, or possibly lunar or Mars mission habitats to see if they would be better than the zeolite sorbents on the 4-bed molecular sieve. Some of the materials being tested are currently used for other industry applications. Studying these sorbents for their specific spacecraft application is different from that for applications on earth because in space, there are certain power, mass, and volume limitations that are not as critical on Earth. In manned-spaceflight missions, the sorbents are exposed to a much lower volume fraction of CO₂ (0.6% volume CO₂) than on Earth.LiLSX was tested for its CO₂ capacity in an atmosphere like that of the ISS. Breakthrough tests were run to establish the capacities of these materials at a partial pressure of CO₂ that is seen on the ISS. This paper discusses experimental results from benchmark materials, such as results previously obtained from tests on Grade 522, and the forementioned candidate materials for the Carbon Dioxide Removal Assembly (CDRA) system.     

How we will go to Mars

This article studies the efficiency of ejecting waste generated by the life support system (LSS) of a manned spacecraft to reduce initial mass on low earth orbit. The spacecraft is used for a long-duration interplanetary mission and is equipped with either a chemical or a nuclear-thermal propulsion system. For this study we simulate an optimal control problem for a given spacecraft maneuver. An impulsive approximation of the optimal interplanetary spacecraft trajectory is assumed, which allows us to reduce the general optimal control problem to hierarchic structure of 'outer' and 'inner' subproblems. This structure is analyzed using the Pontryagin's Maximum principle. Numerical results, illustrating the efficiency of waste ejection are shown for typical Earth-Mars transfer trajectories. This results confirm in theory that using a waste ejection system makes an early manned Mars mission possible without having to design and build new, advanced biological LSS.     

一种在轨补加用浮动断接器设计

对国外的在轨补加用浮动断接器的研究进展进行了总结,在此基础上,提出了一种在轨补加用浮动断接器的设计方案。通过对浮动断接器方案的选择和初步设计,确定了其工作方式、关键技术及解决途径,并进行了初步的原理验证和性能检测。结果表明,浮动断接器原理可行,方案合理,通过进一步的结构优化,可应用于在轨补加。     

Novel aquatic modules for bioregenerative life-support systems based on the closed equilibrated biological aquatic system (C.E.B.A.S.)

The closed equilibrated biological aquatic system (C.E.B.A.S) is a man-made aquatic ecosystem which consists of four subcomponents: an aquatic animal habitat, an aquatic plant bioreactor, an ammonia oxidizing bacteria filter and a data acquisition/control unit. It is a precursor for different types of fish and aquatic plant production sites which are disposed for the integration into bioregenerative life-support systems. The results of two successful spaceflights of a miniaturized C.E.B.A.S version (the C.E.B.A.S. MINI MODULE) allow the optimization of aquatic food production systems which are already developed in the ground laboratory and open new aspects for their utilization as aquatic modules in space bioregenerative life support systems. The total disposition offers different stages of complexity of such aquatic modules starting with simple but efficient aquatic plant cultivators which can be implemented into water recycling systems and ending up in combined plant/fish aquaculture in connection with reproduction modules and hydroponics applications for higher land plants. In principle, aquaculture of fishes and/or other aquatic animals edible for humans offers optimal animal protein production under lowered gravity conditions without the tremendous waste management problems connected with tetrapod breeding and maintenance. The paper presents details of conducted experimental work and of future dispositions which demonstrate clearly that aquaculture is an additional possibility to combine efficient and simple food production in space with water recycling utilizing safe and performable biotechnologies. Moreover, it explains how these systems may contribute to more variable diets to fulfill the needs of multicultural crews.     

Comparative assessment of human–Mars-mission technologies and architectures

We compare a variety of mission scenarios to assess the strengths and weaknesses of options for Mars exploration. The mission design space is modeled along two dimensions: trajectory architectures and propulsion system technologies. We examine direct, semi-direct, stop-over, semi-cycler, and cycler architectures, and we include electric propulsion, nuclear thermal rockets, methane and oxygen production on Mars, Mars water excavation, aerocapture, and reusable propulsion systems in our technology assessment. The mission sensitivity to crew size, vehicle masses, and crew travel time is also examined. Many different combinations of technologies and architectures are applied to the same Mars mission to determine which combinations provide the greatest potential reduction in the injected mass to LEO. We approximate the technology readiness level of a mission to rank development risk, but omit development cost and time calculations in our assessment. It is found that Earth–Mars semi-cyclers and cyclers require the least injected mass to LEO of any architecture and that the discovery of accessible water on Mars has the most dramatic effect on the evolution of Mars exploration.     

Ariane transfer vehicle in service of man in orbit

The Ariane transfer vehicle (ATV), an Ariane 5 borne, unmanned propulsion vehicle, is designed to transport the logistics needed to resupply the International Space Station (ISS) and the man tended free flyer (MTFF) step 2 with pressurized and unpressurized cargo and to dispose the waste. The ATV is an expendable vehicle and is disposed of by a safe atmospheric burn up. In accordance with the AR5 schedule it should be operational in 1996 for missions toward ISS and beyond the year 2000 for MTFF 2 missions. The main constituents of the proposed ATV are the modified AR5 third stage L5, an upgraded VEB steering the launcher as well as the ATV and the P/L-adaptor providing mechanical and umbilical links to the payload. The mechanical part of the RVD-kit will be placed on the payload-module, the main RVD sensors are located on the adaptor and the needed computer intelligence will be integrated on the VEB. To minimize the development, and recurring costs, the ATV concept fully complies to the idea of maximum use of existing hardware and software, mainly from the AR5, Hermes and Columbus programs thus minimizing development and recurring costs. The ATV is compatible to ISS, MTFF and OMV and is able to transport logistic modules compatible with NSTS and U.S.-expendable launchers.     

System design of the Hayabusa 2—Asteroid sample return mission to 1999 JU3

The Japan Aerospace Exploration Agency is currently developing the second asteroid sample return mission, designated as Hayabusa 2. Following the successful return of Hayabusa from the asteroid “Itokawa”, Hayabusa 2 is designed as a round-trip mission to the asteroid “1999 JU3”. The 1999 JU3 is a C-type asteroid, which is believed to contain organic matter and hydrated minerals. Thus, it is expected that successful sample collection will provide additional knowledge on the origin and evolution of the planets and, in particular, the origin of water and organic matter. The current mission scenario will enable the spacecraft to reach 1999 JU3 in the middle of 2018 and perform an asteroid proximity operation for 1.5 years. Three touch downs for sampling and one 2-m-class crater generation by means of a high-speed impact operation are planned during the asteroid proximity operation. The samples are to be brought back to the Earth by a re-entry capsule. The present paper describes the system design of Hayabusa 2, some key technical challenges of the mission, and the development status.     

Mission to Mars using integrated propulsion concepts: considerations, opportunities, and strategies

The aim of this paper is to evaluate the feasibility of a mission to Mars using the Integrated Propulsion Systems (IPS) which means to couple Nuclear-MPD-ISPU propulsion systems. In particular both mission analysis and propulsion aspects are analyzed together with technological aspects. Identifying possible mission scenarios will lead to the study of possible strategies for Mars Exploration and also of methods for reducing cost. As regard to IPS, the coupling between Nuclear Propulsion (Rubbia's engine) and Superconductive MPD propulsion is considered for the Earth-Mars trajectories: major emphasis is given to the advantages of such a system. The In Situ Resource Utilization (ISRU) concerns on-Mars operations; In Situ Propellant Utilization (ISPU) is foreseen particularly for LOX-CH4 engines for Mars Ascent Vehicles and this possibility is analyzed from a technological point of view. Tether Systems are also considered during interplanetary trajectories and as space elevators on Mars orbit. Finally strategic considerations associated to this mission are considered also.     

Combining solar science and asteroid science with the space weather observation network (SWON)

The peculiarity of space weather for Earth orbiting satellites, air traffic and power grids on Earth and especially the financial and operational risks posed by damage due to space weather, underline the necessity of space weather observation. The importance of such observations is even more increasing due to the impending solar maximum. In recognition of this importance we propose a mission architecture for solar observation as an alternative to already published mission plans like Solar Probe (NASA) or Solar Orbiter (ESA). Based upon a Concurrent Evaluation session in the Concurrent Engineering Facility of the German Aerospace Center, we suggest using several spacecraft in an observation network. Instead of placing such spacecraft in a solar orbit, we propose landing on several asteroids, which are in opposition to Earth during the course of the mission and thus allow observation of the Sun's far side. Observation of the far side is especially advantageous as it improves the warning time with regard to solar events by about 2 weeks. Landing on Inner Earth Object (IEO) asteroids for observation of the Sun has several benefits over traditional mission architectures. Exploiting shadowing effects of the asteroids reduces thermal stress on the spacecraft, while it is possible to approach the Sun closer than with an orbiter. The closeness to the Sun improves observation quality and solar power generation, which is intended to be achieved with a solar dynamic system. Furthermore landers can execute experiments and measurements with regard to asteroid science, further increasing the scientific output of such a mission. Placing the spacecraft in a network would also benefit the communication contact times of the network and Earth. Concluding we present a first draft of a spacecraft layout, mission objectives and requirements as well as an initial mission analysis calculation.     

低功率水电弧加热发动机的初步研究

本文研究了以水为推进剂的电弧加热发动机。其中电弧加热发动机的流量为15mg/s、电流为8A,此时平均电压为80.5V、功率约为640W、平均推力为0.0975N,以此计算得到比冲为650s左右、效率为55%～60%。成功地验证了水做为电弧加热发动机的推进剂、产生推力的能力。     

Nuclear waste disposal in space: Implications of advanced space transportation

Previous studies have shown that the disposal of nuclear waste in space is promising as a practical and economically plausible option, based on use of the first generation space shuttle. The promise brightens if we consider use of more effective second generation systems such as fully reusable single-stage-to-orbit transports. These vehicles, with simpler more reliable flight characteristics and with operational economics at least twenty times more favorable than the first shuttle, can become available in the early 1990s when the nuclear waste problem will have grown to truly serious proportions. This paper surveys both vertical and horizontal-takeoff vehicles as they could be used for the Earth-to-orbit phase of nuclear waste disposal mission. The international nature of the nuclear waste issue is emphasized, and the suggestion is made that an international equatorial launch site be established. This launch center, apart from its inherent safety features, would serve as a focus for an international solution of the truly worldwide problem of nuclear waste disposal.     

卫星总体优化设计研究

结合传统卫星总体设计思想和现代优化方法，对卫星总体优化设计的概念、研究内容进行了分析，并且提出了卫星总体优化设计流程，即：首先将用户提出的任务目标转化成任务要求，进而进行总体方案类型优选。然后在此基础上进行总体参数优化设计，最后形成满足用户任务目标和任务要求的最佳总体方案设计文件。     

Aquatic modules for bioregenerative life support systems based on the C.E.B.A.S. biotechnology [correction of biotechnilogy

Most concepts for bioregenerative life support systems are based on edible higher land plants which create some problems with growth and seed generation under space conditions. Animal protein production is mostly neglected because of the tremendous waste management problems with tetrapods under reduced weightlessness. Therefore, the "Closed Equilibrated Biological Aquatic System" (C.E.B.A.S.) was developed which represents an artificial aquatic ecosystem containing aquatic organisms which are adapted at all to "near weightlessness conditions" (fishes Xiphophorus helleri, water snails Biomphalaria glabrata, ammonia oxidizing bacteria and the rootless non-gravitropic edible water plant Ceratophyllum demersum). Basically the C.E.B.A.S. consists of 4 subsystems: a ZOOLOGICAL (correction of ZOOLOGICASL) COMPONENT (animal aquarium), a BOTANICAL COMPONENT (aquatic plant bioreactor), a MICROBIAL COMPONENT (bacteria filter) and an ELECTRONICAL COMPONENT (data acquisition and control unit). Superficially, the function principle appears simple: the plants convert light energy into chemical energy via photosynthesis thus producing biomass and oxygen. The animals and microorganisms use the oxygen for respiration and produce the carbon dioxide which is essential for plant photosynthesis. The ammonia ions excreted by the animals are converted by the bacteria to nitrite and then to nitrate ions which serve as a nitrogen source for the plants. Other essential ions derive from biological degradation of animal waste products and dead organic matter. The C.E.B.A.S. exists in 2 basic versions: the original C.E.B.A.S. with a volume of 150 liters and a self-sustaining standing time of more than 13 month and the so-called C.E.B.A.S. MINI MODULE with a volume of about 8.5 liters. In the latter there is no closed food loop by reasons of available space so that animal food has to be provided via an automated feeder. This device was flown already successfully on the STS-89 and STS-90 spaceshuttle missions and the working hypothesis was verified that aquatic organisms are nearly not affected at all by space conditions, i.e. that the plants exhibited biomass production rates identical to the sound controls and that as well the reproductive, and the immune system as the embryonic and ontogenic development of the animals remained undisturbed. Currently the C.E.B.A.S. MINI MODLULE is prepared for a third spaceshuttle flight (STS-107) in spring 2001. Based on the results of the space experiments a series of prototypes of aquatic food production modules for the implementation into BLSS were developed. This paper describes the scientific disposition of the STS-107 experiment and of open and closed aquaculture systems based on another aquatic plant species, the Lemnacean Wolffia arrhiza which is cultured as a vegetable in Southeastern Asia. This plant can be grown in suspension culture and several special bioreactors were developed for this purpose. W. arrhiza reproduces mainly vegetatively by buds but also sexually from time to time and is therefore especially suitable for genetic engineering, too. Therefore it was used, in addition, to optimize the C.E.B.A.S. MINI MODULE to allow experiments with a duration of 4 month in the International Space Station the basic principle of which will be explained. In the context of aquaculture systems for BLSS the continuous replacement of removed fish biomass is an essential demand. Although fish reproduction seems not to be affected in the shortterm space experiments with the C.E.B.A.S. MINI MODULE a functional and reliable hatchery for the production of siblings under reduced weightlessness is connected with some serious problems. Therefore an automated "reproduction module" for the herbivorous fish Tilapia rendalli was developed as a laboratory prototype. It is concluded that aquatic modules of different degrees of complexity can optimize the productivity of BLSS based on higher land plants and that they offer an unique opportunity for the production of animal protein in lunar or planetary bases.     

Venus, Mars, and the ices on Mercury and the moon: astrobiological implications and proposed mission designs

Venus and Mars likely had liquid water bodies on their surface early in the Solar System history. The surfaces of Venus and Mars are presently not a suitable habitat for life, but reservoirs of liquid water remain in the atmosphere of Venus and the subsurface of Mars, and with it also the possibility of microbial life. Microbial organisms may have adapted to live in these ecological niches by the evolutionary force of directional selection. Missions to our neighboring planets should therefore be planned to explore these potentially life-containing refuges and return samples for analysis. Sample return missions should also include ice samples from Mercury and the Moon, which may contain information about the biogenic material that catalyzed the early evolution of life on Earth (or elsewhere). To obtain such information, science-driven exploration is necessary through varying degrees of mission operation autonomy. A hierarchical mission design is envisioned that includes spaceborne (orbital), atmosphere (airborne), surface (mobile such as rover and stationary such as lander or sensor), and subsurface (e.g., ground-penetrating radar, drilling, etc.) agents working in concert to allow for sufficient mission safety and redundancy, to perform extensive and challenging reconnaissance, and to lead to a thorough search for evidence of life and habitability.     

DARA vestibular equipment onboard MIR

In space, the weightless environment provides a different stimulus to the otolith organs of the vestibular system, and the resulting signals no longer correspond with the visual and other sensory signals sent to the brain. This signal conflict causes disorientation. To study this and also to understand the vestibular adaptation to weightlessness, DARA has developed scientific equipment for vestibular and visuo-oculomotoric investigations. Especially, two video-oculography systems (monocular--VOG--and binocular--BIVOG, respectively) as well as stimuli such as an optokinetic stimulation device have successfully been employed onboard MIR in the frame of national and European missions since 1992. The monocular VOG was used by Klaus Flade during the MIR '92 mission, by Victor Polyakov during his record 15 months stay onboard MIR in 1993/94 as well as by Ulf Merbold during EUROMIR '94. The binocular version was used by Thomas Reiter and Sergej Avdeyev during the 6 months EUROMIR '95 mission. PIs of the various experiments include H. Scherer and A. Clarke (FU Berlin), M. Dieterichs and S. Krafczyk (LMU Munchen) from Germany as well as C.H. Markham and S.G. Diamond from the United States. Video-Oculography (VOG) is a technique for examining the function of the human balance system located in the inner ear (vestibular system) and the visio-oculomotor interactions of the vestibular organ. The human eye movements are measured, recorded and evaluated by state-of-the-art video techniques. The method was first conceived and designed at the Vestibular Research Laboratory of the ENT Clinic in Steglitz, FU Berlin (A. Clarke, H. Scherer). Kayser-Threde developed, manufactured and tested the facilities for space application under contract to DARA. Evaluation software was first provided by the ENT Clinic, Berlin, later by our subcontractor Sensomotoric Instruments (SMI), Teltow. Optokinetic hardware to support visuo-oculomotoric investigations, has been shipped to MIR for EUROMIR '95 and has successfully been used in conjunction with VOG by ESA astronaut Thomas Reiter. Most recently, BIVOG aboard MIR will be reused in the frame of German/Russian joint experiment sessions employing two Russian cosmonauts from August 1997 to January 1998.     

液氧/煤油发动机试验废水的循环使用

为达到国标中有关污水排放的二级标准及节约利用水资源,设计和安装了液氧/煤油发动机试验台试验污水处理和循环使用系统。发动机试验采用水冷式导流槽,每次试验的用水量很大,并且试验产生的废水会含有一定量的煤油,该处理系统采用过滤-吸附-消毒等工艺对试验产生的污水进行处理,并将处理后的污水进行循环使用。系统投入使用后污水处理效果理想,且运行稳定、便于维护。     

LISA — a study of the ESA cornerstone mission for observing gravitational waves

The primary objective of the Laser Interferometer Space Antenna (LISA) mission is to detect and observe gravitational waves from massive black holes and galactic binaries in the frequency range 10⁻⁴ to 10⁻¹ Hz. This low-frequency range is inaccessible to ground-based interferometers because of the unshieldable background of local gravitational noise and because ground-based interferometers are limited in length to a few km. LISA is an ESA cornerstone mission and recently had a system study (Ref. 1) carried out by a consortium led by Astrium, which confirmed the basic configuration for the payload with only minor changes, and provided detailed concepts for the spacecraft and mission design. The study confirmed the need for a drag-free technology demonstration mission to develop the inertial sensors for LISA, before embarking on the build of the flight sensors. With a technology demonstration flight in 2005, it would be possible to carry out LISA as a joint ESA-NASA mission with a launch by 2010 subject to the funding programmatics. The baseline for LISA is three disc-like spacecraft each of which consist of a science module which carries the laser interferometer payload (two in each science module) and a propulsion module containing an ion drive and the hydrazine thrusters of the AOCS. The propulsion module is used for the transfer from earth escape trajectory provided by the Delta II launch to the operational orbit. Once there the propulsion module is jettisoned to reduce disturbances on the payload. Detailed analysis of thermal and gravitational disturbances, a model of the drag-free control and of the interferometer operation confirm that the strain sensitivity of the interferometer will be achieved.     

LIFE: Life Investigation For Enceladus A Sample Return Mission Concept in Search for Evidence of Life

Abstract Life Investigation For Enceladus (LIFE) presents a low-cost sample return mission to Enceladus, a body with high astrobiological potential. There is ample evidence that liquid water exists under ice coverage in the form of active geysers in the "tiger stripes" area of the southern Enceladus hemisphere. This active plume consists of gas and ice particles and enables the sampling of fresh materials from the interior that may originate from a liquid water source. The particles consist mostly of water ice and are 1-10?μ in diameter. The plume composition shows H(2)O, CO(2), CH(4), NH(3), Ar, and evidence that more complex organic species might be present. Since life on Earth exists whenever liquid water, organics, and energy coexist, understanding the chemical components of the emanating ice particles could indicate whether life is potentially present on Enceladus. The icy worlds of the outer planets are testing grounds for some of the theories for the origin of life on Earth. The LIFE mission concept is envisioned in two parts: first, to orbit Saturn (in order to achieve lower sampling speeds, approaching 2 km/s, and thus enable a softer sample collection impact than Stardust, and to make possible multiple flybys of Enceladus); second, to sample Enceladus' plume, the E ring of Saturn, and the Titan upper atmosphere. With new findings from these samples, NASA could provide detailed chemical and isotopic and, potentially, biological compositional context of the plume. Since the duration of the Enceladus plume is unpredictable, it is imperative that these samples are captured at the earliest flight opportunity. If LIFE is launched before 2019, it could take advantage of a Jupiter gravity assist, which would thus reduce mission lifetimes and launch vehicle costs. The LIFE concept offers science returns comparable to those of a Flagship mission but at the measurably lower sample return costs of a Discovery-class mission. Key Words: Astrobiology-Habitability-Enceladus-Biosignatures. Astrobiology 12, 730-742.     

Potential cost reductions for three STS/Spacelab mission modes

Based on the results of studies carried out by ESA several possibilities are discussed to achieve mission cost reductions for large Spacelab instrument facilities as compared to their flight on several 7-day duration Spacelab missions. As an example three scientific telescope facilities are selected (LIRTS, EXSPOS, GRIST) which are defined to a Phase A level.Three new mission modes are considered:

• —Shuttle attached Spacelab mission mode with extended flight duration (up to 30 days) for which the application of planned capability extensions and new elements of the STS/Spacelab (e.g. Short Spacelab Pallets, Power Extension Package) are investigated.

• —Shuttle deployed mission mode, for which the telescope, accommodated on a Spacelab pallet, is docked to the Power Module, a new element of the Space Transportation System under study by NASA.

• —Free-flying mission mode, for which Shuttle launched dedicated missions of the facilities are considered, assuming varying degrees of autonomy with respect to supporting services of the Shuttle.

Reduction of costs have been considered on the levels of single mission cost and total programme cost. Fundamentally the charges for the instrument can be reduced by constraining the mass/volume factors with respect to the Shuttle capability. However, the instrument as part of a payload is only viable if an acceptable resource sharing including observation time can be achieved. Any single instrument will require several mission opportunities or one mission which achieves a similar or longer total observation programme.Based on an identification of instrument modifications of the Phase A baseline designs to favour cost reductions and on a derivation of technical requirements, constraints and finally budgetary cost comparisons an attempt is made to assess the advantages and disadvantages of the different mission modes.The favoured option for GRIST is a 2–3 weeks sortie mission followed after refurbishment by a longer Power Module docked mission. For LIRTS and EXSPOS the free-flying pallet modes are very attractive in terms of the longer durations achieved and in terms of cost per unit operating time.     

低温推进剂在轨加注技术与方案研究综述

为了探究适用于低温推进剂在轨加注的相关技术与方案,通过文献调研与对比分析,介绍国内外在轨加注技术的研究现状,梳理低温推进剂在轨加注的关键技术,研究现有加注技术与方案对低温推进剂的适用性,并提出我国开展相关研究的思路与方向。研究表明：1）气液分离、蒸发量控制、质量测量和流体驱动循环等技术是直接影响推进剂在轨加注系统结构与加注性能的关键技术;2）低温推进剂具有沸点低、表面张力小等特殊性,对气液分离、系统热防护等技术的性能要求更高;3）表面张力式气液分离、纤维镜或射频质量检测、多层隔热材料、热力学排气系统（TVS）以及无排气加注等先进技术方案对低温流体和微重力环境均具有更好的适用性,将成为实现低温推进剂在轨加注的关键突破口。