Desert RATS 2011: Human and robotic exploration of near-Earth asteroids

The Desert Research and Technology Studies (D-RATS) 2011 field test involved the planning and execution of a series of exploration scenarios under operational conditions similar to those expected during a human exploration mission to a near-Earth asteroid (NEA). The focus was on understanding the operations tempo during simulated NEA exploration and the implications of communications latency and limited data bandwidth. Anchoring technologies and sampling techniques were not evaluated due to the immaturity of those technologies and the inability to meaningfully test them at D-RATS. Reduced gravity analogs and simulations are being used to fully evaluate Space Exploration Vehicle (SEV) and extravehicular (EVA) operations and interactions in near-weightlessness at a NEA as part of NASA's integrated analogs program. Hypotheses were tested by planning and performing a series of 1-day simulated exploration excursions comparing test conditions all of which involved a single Deep Space Habitat (DSH) and either 0, 1, or 2 SEVs; 3 or 4 crewmembers; 1 of 2 different communications bandwidths; and a 50-second each-way communications latency between the field site and Houston. Excursions were executed at the Black Point Lava Flow test site with a remote Mission Control Center and Science Support Room at Johnson Space Center (JSC) being operated with 50-second each-way communication latency to the field. Crews were composed of astronauts and professional field geologists. Teams of Mission Operations and Science experts also supported the mission simulations each day. Data were collected separately from the Crew, Mission Operations, and Science teams to assess the test conditions from multiple perspectives. For the operations tested, data indicates practically significant benefits may be realized by including at least one SEV and by including 4 versus 3 crewmembers in the NEA exploration architecture as measured by increased scientific data quality, EVA exploration time, capability assessment ratings, and consensus acceptability ratings provided by Crew, Mission Operations, and Science teams. A combination of text and voice was used to effectively communicate over the communications latency, and increased communication bandwidth yielded a small but practically significant improvement in overall acceptability as rated by the Science team, although the impact of bandwidth on scientific strategic planning and public outreach was not assessed. No effect of increased bandwidth was observed with respect to Crew or Mission Operations team ratings of overall acceptability.     

MarcoPolo-R: Near-Earth Asteroid sample return mission selected for the assessment study phase of the ESA program cosmic vision

This paper presents the sample return mission to a primitive Near-Earth Asteroid (NEA) MarcoPolo-R proposed to the European Space Agency in December 2010. MarcoPolo-R was selected in February 2011 with three other missions addressing different science objectives for the two-year Assessment Phase of the Medium-Class mission competition of the Cosmic Vision 2 program for launch in 2022. The baseline target of MarcoPolo-R is the binary NEA (175706) 1996 FG3, which offers an efficient operational and technical mission profile. A binary target also provides enhanced science return. The choice of a binary target allows several scientific investigations to occur more easily than through a single object, in particular regarding the fascinating geology and geophysics of asteroids. MarcoPolo-R will rendezvous with a primitive, organic-rich NEA, scientifically characterize it at multiple scales, and return a bulk sample to Earth for laboratory analyses. The MarcoPolo-R sample will provide a representative sample from the surface of a known asteroid with known geologic context, and will contribute to the inventory of primitive material that is probably missing from the meteorite collection. The MarcoPolo-R samples will thus contribute to the exploration of the origin of planetary materials and initial stages of habitable planet formation, to the identification and characterization of the organics and volatiles in a primitive asteroid and to the understanding of the unique geomorphology, dynamics and evolution of a binary asteroid that belongs to the Potentially Hazardous Asteroid (PHA) population.     

NEEMO 7 undersea mission

The NEEMO 7 mission was the seventh in a series of NASA-coordinated missions utilizing the Aquarius undersea habitat in Florida as a human space mission analog. The primary research focus of this mission was to evaluate telementoring and telerobotic surgery technologies as potential means to deliver medical care to astronauts during spaceflight. The NEEMO 7 crewmembers received minimal pre-mission training to perform selected medical and surgical procedures. These procedures included: (1) use of a portable ultrasound to locate and measure abdominal organs and structures in a crewmember subject; (2) use of a portable ultrasound to insert a small needle and drain into a fluid-filled cystic cavity in a simulated patient; (3) surgical repair of two arteries in a simulated patient; (4) cystoscopy and use of a ureteral basket to remove a renal stone in a simulated patient; and (5) laparoscopic cholecystectomy in a simulated patient. During the actual mission, the crewmembers performed the procedures without or with telementoring and telerobotic assistance from experts located in Hamilton, Ontario. The results of the NEEMO 7 medical experiments demonstrated that telehealth interventions rely heavily on a robust broadband, high data rate telecommunication link; that certain interventional procedures can be performed adequately by minimally trained individuals with telementoring assistance; and that prior clinical experience does not always correlate with better procedural performance. As space missions become longer in duration and take place further from Earth, enhancement of medical care capability and expertise will be required. The kinds of medical technologies demonstrated during the NEEMO 7 mission may play a significant role in enabling the human exploration of space beyond low earth orbit, particularly to destinations such as the Moon and Mars.     

A permanently-acting NEA damage mitigation technique via the Yarkovsky effect

In the later stages of a combined mission of exploration and damage mitigation of a hazardous Near Earth Asteroid (NEA), sufficiently detailed tracking, orbit prediction, mass distribution, and physical properties data have been accumulated. It may be desirable to implement a “slow push” damage mitigation technique that is capable of altering the NEA orbit continuously and permanently. This possibility was suggested in a companion paper that outlined an archetypal exploration/mitigation mission to the NEA 99942 Apophis, which is achieved using a novel albedo change approach. The details and apparatus used in the albedo modification technique are described in the paper. We describe the design details and the constraints on particle size (to prevent electrostatic levitation and escape) and on the dispensing speed (to achieve the desired coverage zone and prevent particles from orbiting or escaping).     

One hundred US EVAs: a perspective on spacewalks

In the 36 years between June 1965 and February 2001, the US human space flight program has conducted 100 spacewalks, or extravehicular activities (EVAs), as NASA officially calls them. EVA occurs when astronauts wearing spacesuits travel outside their protective spacecraft to perform tasks in the space vacuum environment. US EVA started with pioneering feasibility tests during the Gemini Program. The Apollo Program required sending astronauts to the moon and performing EVA to explore the lunar surface. EVA supported scientific mission objectives of the Skylab program, but may be best remembered for repairing launch damage to the vehicle and thus saving the program. EVA capability on Shuttle was initially planned to be a kit that could be flown at will, and was primarily intended for coping with vehicle return emergencies. The Skylab emergency and the pivotal role of EVA in salvaging that program quickly promoted Shuttle EVA to an essential element for achieving mission objectives, including retrieving satellites and developing techniques to assemble and maintain the International Space Station (ISS). Now, EVA is supporting assembly of ISS. This paper highlights development of US EVA capability within the context of the overarching mission objectives of the US human space flight program.     

Innovations in mission architectures for exploration beyond low Earth orbit

Through the application of advanced technologies and mission concepts, architectures for missions beyond Earth orbit have been dramatically simplified. These concepts enable a stepping stone approach to science driven; technology enabled human and robotic exploration. Numbers and masses of vehicles required are greatly reduced, yet the pursuit of a broader range of science objectives is enabled. The scope of human missions considered range from the assembly and maintenance of large aperture telescopes for emplacement at the Sun-Earth libration point L2, to human missions to asteroids, the moon and Mars. The vehicle designs are developed for proof of concept, to validate mission approaches and understand the value of new technologies. The stepping stone approach employs an incremental buildup of capabilities, which allows for future decision points on exploration objectives. It enables testing of technologies to achieve greater reliability and understanding of costs for the next steps in exploration.     

Energy utilization rates during shuttle extravehicular activities

The work rates or energy utilization rates during EVA are major factors in sizing of life support systems. These rates also provide a measure of ease of EVA and its cost in crew fatigue. From the first Shuttle EVA on the STS-6 mission in 1983, we have conducted 59 man-EVA and 341 man-hours of EVA. Energy utilization rates have been measured on each of these EVA. Metabolic rate was measured during each EVA using oxygen utilization corrected for suit leakage. From 1981–1987, these data were available for average data over the EVA or over large segments of the EVA. Since 1987, EVA oxygen utilization data were available at 2-minute intervals. The average metabolic rate on Shuttle EVA (194 kcal/hr.) has been significantly lower than metabolic rates during Apollo and Skylab missions. Peak rates have been below design levels, infrequent, and of short duration. The data suggest that the energy cost of tasks may be inversely related to the degree of training for the task. The data provide insight on the safety margins provided by life support designs and on the energy cost of Station construction EVA.     

载人火星探测任务方案构想

提出了一种我国2030年代载人火星探测任务实施方案的构想。通过分批式提前部署方式,分别按货运、载人两个阶段实施对我国载人登火并对火星探测。其中,载人阶段在返回地球时可利用金星借力的方式以缩短整个载人任务周期。利用重型运载和长征五号运载火箭,分别在海南文昌和西昌卫星发射中心发射,实现2030年代的我国载人火星探测。     

Crew autonomy for deep space exploration: Lessons from the Antarctic Search for Meteorites

Future piloted missions to explore asteroids, Mars, and other targets beyond the Moon will experience strict limitations on communication between vehicles in space and control centers on Earth. These limitations will require crews to operate with greater autonomy than any past space mission has demonstrated. The Antarctic Search for Meteorites (ANSMET) project, which regularly sends small teams of researchers to remote parts of the southern continent, resembles a space mission in many ways but does not rely upon a control center. It provides a useful crew autonomy model for planners of future deep space exploration missions. In contrast to current space missions, ANSMET gives the crew the authority to adjust competing work priorities, task assignments, and daily schedules; allows the crew to be the primary monitor of mission progress; demands greater crew accountability for operational errors; requires the crew to make the most of limited communication bandwidth; adopts systems designed for simple operation and failure recovery; and grants the crew a leading role in the selection and stowage of their equipment.     

美国小行星俘获任务及其启示

小行星俘获(ACR)任务是美国Keck空间研究中心发起的一项深空探测任务。该任务计划选定一颗近地小行星,通过口袋式抓捕系统对其实施抓捕,并于2025年左右将其带回近月空间。文章介绍了ACR任务的内容和系统设计,具体包括:航天器总体构型、抓捕分系统、探测识别分系统和控制与推进分系统;对小行星抓捕的目标探测与识别、旋转匹配、抓捕、消旋、轨道转移等核心操作。基于ACR任务,提出了空间目标俘获技术的需求与应用、抓捕航天器系统设计的启示;基于我国目前的技术研究情况,总结分析了发展空间目标俘获任务所需的关键技术,如大功率柔性太阳翼、长时间大范围轨道机动、目标探测与识别、快速机动、目标抓捕与消旋。     

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.     

EVA Suit 2000: a joint European/Russian space suit design

A feasibility study in 1992 showed the benefits of a common European Russian space suit development, EVA Suit 2000, replacing the Russian space suit Orlan-DMA and the planned European Hermes EVA space suit at the turn of the century. This EVA Suit 2000 is a joint development initiated by the European Space Agency (ESA) and the Russian Space Agency (RKA). The main objectives of this development program are: first utilization aboard the Russian Space Station MIR-2; performance improvement with respect to current operational suits; development cost reduction. Russian experience gained with the present extravehicular activity (EVA) suit on the MIR Space Station and extensive application of European Technologies will be needed to achieve these ambitious goals. This paper presents the current status of the development activities, the space suit system design and concentrates in more detail on life support aspects. Specific subjects addressed will include the overall life support conceptual architecture, design features, crew comfort and operational considerations.     

Public support for Mars missions: The importance of informing the next generation

This paper explores and compares the perceptions of the risks associated with Mars Sample Return (MSR) among schoolchildren and adults. Comparable surveys were constructed and administered to two sample groups; science students aged 11–15 and adults with an interest in science aged 18 and over. Contingency table analyses were used to quantify any differences in perception between the two groups. Schoolchildren were less likely to consider Mars exploration to be quite or very useful (44.7% vs. 68.9%; p=0.005) and recorded significantly higher levels of risk perception regarding both a MSR mission and also towards other societal risks. These results have important implications for policy-makers, as they can inform education programs now that will enhance the viability and public support for future missions.     

国外载人航天器回收着陆技术的进展

进入21世纪,国际上掀起了一个空间探索活动的新高潮,而作为载人空间探索活动重要支撑的回收和着陆技术也相应取得了重要进展。文章综述了关、欧、俄在载人飞船、登月舱、火星着陆器等载人航天器回收着陆技术方面的研究和进展。     

Dextre: Improving maintenance operations on the International Space Station

The Special Purpose Dexterous Manipulator (SPDM), known as “Dextre”, is currently slated to launch in February 2008 for deployment on the International Space Station (ISS) as the final component of Canada's Mobile Servicing System (MSS). Dextre's primary role on the Space Station is to perform repair and replacement (R&R) maintenance tasks on robotically compatible hardware such as Orbital Replaceable Units (ORUs), thereby eventually easing the burden on the ISS crew.This burden on the on-orbit crew translates practically into crew time being a limited resource on the ISS, and as such, finding ways to assist the crew in performing their tasks or offloading the crew completely when appropriate is a bonus to the ISS program. This is already accomplished very effectively by commanding as many non-critical robotics tasks as possible, such as powering up and free-space maneuvering of the Space Station Remote Manipulator System (SSRMS), known as “Canadarm2”, from the Ground.Thus, beyond its primary role, and based on an increasing clarity regarding the challenges of external maintenance on the ISS, Dextre is being considered for use in a number of ways with the objective of improving ISS operations while reducing and optimizing the use of crew time through the use of ground control for various tasks, pre-positioning hardware, acting as a temporary storage platform to break an Extra Vehicular Activity (EVA) day into manageable timelines, and extending the physical reach and range of the Canadarm2.This paper discusses the planned activities and operations for Dextre an rationale for how these will help optimize the use of crew resources on the ISS.     

A methodology to support strategic decisions in future human space exploration: From scenario definition to building blocks assessment

The human exploration of multiple deep space destinations (e.g. Cis-Lunar, NEAs), in view of the final challenge of sending astronauts to Mars, represents a current and consistent study domain especially in terms of its possible scenarios and mission architectures assessments, as proved by the numerous on-going activities about this topic and moreover by the global exploration roadmap. After exploring and analysing different possible solutions to identify the most flexible path, a detailed characterisation of several Design Reference Missions (DRMs) represents a necessity in order to evaluate the feasibility and affordability of deep space exploration missions, specifically in terms of enabling technological capabilities.The study presented in this paper was aimed at defining an evolutionary scenario for deep space exploration in the next 30 years with the final goal of sending astronauts on the surface of Mars by the end of 2030 decade. Different destinations were considered as targets to build the human exploration scenario, with particular attention to Earth–Moon Lagrangian points, NEA and Moon. For all the destinations selected as part of the exploration scenario, the assessment and characterisation of the relative Design Reference Missions were performed. Specifically they were defined in terms of strategies, architectures and mission elements. All the analyses were based on a pure technical approach with the objective of evaluating the feasibility of a long term strategy for capabilities achievement and technological development to enable future space exploration.This paper describes the process that was followed within the study, focusing on the adopted methodology, and reports the major obtained results, in terms of scenario and mission analysis.     

基于近场测量的阵列天线校准

阵列天线校准是精确控制阵列波束方向和辐射方向图的前提。本文依据测量距离将阵列天线校准方法分为远场校准法和近场校准法两类。随着阵列天线大型化的发展趋势,微波暗室的尺寸越来越难达到阵列天线远场的要求,远场校准法的适用性逐渐减弱,对近场校准法的需求逐渐增加。本文梳理了过往的经典近场校准方法,并对近场校准方法的最新进展进行论述,对不同校准方法的原理做了详细分析和对比,最后给出未来校准研究的发展方向。     

基于综合平面波技术的近远场变换

近场散射数据的远场变换研究是具有发展前景的由近场测量目标,获取目标远场雷达截面的方法之一。根据近场获得的散射数据,外推获取远场的目标散射特性。主要是利用平面波谱展开,推导了近远场转换公式;以导体圆柱、平板等简单物体作为散射体仿真了近场散射数据的远场变换,证明了方法的可行性和正确性。