Conversations: with Carl Pilcher [interview by Johan Benson

An interview with Carl Pilcher, science program director for solar system exploration at NASA, examines NASA's past, present, and planned missions to explore the solar system. Specific questions relate to the status of current and planned missions, science results of the Pathfinder mission to Mars, cooperation with the Japanese space agency, the status of the search for extraterrestrial life in solar system meteoroids and asteroids, mission size for more in-depth exploration, reports of water on the moon, and the exploration of near-Earth objects.     

Engineering test beds on the International Space Station

The International Space Station is a unique multi-faceted orbiting laboratory supporting research, development, test and evaluation of new innovative space and Earth-based applications. While NASA sponsored investigations on the ISS are focused largely on enabling future long duration human space exploration missions, Congress designated the US portion of the space station as a National Laboratory making its facilities available to other Federal agencies and private entities for non-exploration related ventures. RDT&E activities on the ISS encompass a number of technical areas including environmental control and life support, communications, materials science, guidance, navigation and control, propulsion, electrical power, and thermal control systems.     

Decisions, endings, and new beginnings

The Washington Watch column examines NASA shuttle developments, airline pilot age issues, development of a personnel recovery vehicle, and includes an obituary for retired Air Force General Bernard Schriever, remembered as an air and space pioneer. The discussion of NASA shuttle developments reports on the space shuttle flight schedule and NASA's ability to deliver hardware to the International Space Station, funding levels and equipment development schedules related to President Bush's mandate to visit Mars, a report on the space program by the American Academy of Arts and Sciences, and top-level management changes at NASA. The discussion of airline pilot age issues examines efforts to change mandatory retirement requirements. The discussion of personnel recovery vehicles reports on development of an aircraft designed to rescue survivors during combat search and rescue missions.     

The image/poetry education and public outreach program

Education and public outreach are viewed by NASA as significant undertakings for all of its space missions. The IMAGE satellite is one of the first missions to explicitly include `E&PO in its original proposal to NASA in 1996. We will discuss what IMAGE has accomplished in this area to date, and what new activities it will conduct following a successful launch.     

Steering the station back on course

Rising costs of the International Space Station prompted NASA to convene a panel of experts to assess the quality of ISS cost estimates and review program assumptions and requirements. The panel concluded that NASA was unable to accurately predict ISS costs or to support requests for increased funding for the ISS through 2006 and should maintain a U.S. core complete program with three-person crews with 6-month stays on the ISS. International response to the panel report was negative with space agencies from Japan, Russia, Canada, and Europe taking issue with the expected impact on ISS construction and use.     

太空环境下电子束原位制造技术

美国国家航空航天局（NASA）载人探索计划的提出给载人登月和载人火星等带来了机会和风险,NASA的工程师和科学家正在开展在月球或火星表面利用当地提炼的材料进行原位制造工艺技术的研究。首先,介绍了太空原位制造和修复（ISFR）技术的概念和特点,结合该技术的发展背景,介绍了电子束原位制造技术的概念、特点以及在太空环境下应用的优势和潜力。然后,根据所用原材料和成形工艺原理的不同,电子束原位制造技术又分为电子束熔融（EBM）和电子束自由成形制造（EBF³）技术两个分支,分别介绍了这两个分支技术的概念、原理、特点以及采用该技术研制出的零件的性能,结合硬件设备的情况介绍了在太空环境下应用的适用性,同时也详细介绍了NASA利用兰利研究中心的C-9抛物线飞行试验系统进行电子束原位制造微重力试验的研究成果、试验数据和未来的发展趋势。最后,结合中国未来空间事业发展的需要,提出了关于发展太空环境下电子束原位制造技术的设想与建议。     

High efficiency dynamic radioisotope power systems for spaceexploration-a status report

Background on the space exploration program is discussed, and the currently identified NASA exploration missions are contrasted with the missions that were being planned a year ago. Developments in high-efficiency dynamic radioisotope power systems are discussed: and Brayton and Stirling power conversion cycles are compared for the missions planned for the next decade. Issues related to the use of high-efficiency radioisotope (HER) power systems are identified. It is noted that HER power systems are approximately three times as efficient as current radioisotope thermoelectric generators(RTGs) and are therefore significantly cheaper. Additionally, the world's supply of ²³⁸Pu is extremely limited. Currently discussed missions would cut deeply into this supply if powered by RTGs     

Conversations with John H. Glenn Jr. Interview by Frank Sietzen Jr

Senator Glenn is interviewed about his experiences on Friendship 7 and the Shuttle Discovery, expectations of early astronauts, lunar missions, the International Space Station, international dimensions of space activities, public confidence in NASA, attracting young people to the aerospace industry, highlights of his career, and the future of flight.     

Ultra-lightweight space power from hybrid thin-film solar cells

The development of hybrid inorganic/organic thin-film solar cells on flexible, lightweight, space-qualified, durable substrates provides an attractive solution for space power generation with high mass specific power (W/kg). The high-volume, low-cost fabrication potential of organic cells will allow for square miles of solar cell production at one-tenth the cost of conventional inorganic materials. Plastic solar cells take a minimum of storage space and can be inflated or unrolled for deployment. We explore a cross-section of NASA in-house and sponsored research efforts that aim to provide new hybrid technologies that include both inorganic and polymer materials as active and substrate materials. For NASA applications, any solar cell or array technology must not only meet weight and AMO efficiency goals, but also must be durable enough to survive launch and space environments. Also, balance of system technologies must be developed to take advantage of ultra-lightweight solar arrays in power generation systems.     

我国空间站工程量化风险评价工作探讨

为适应我国载人航天任务的新特点,有效支持空间站量化风险评价工作,调研了美国国家航空航天局（NASA）载人登月、国际空间站、航天飞机等载人航天项目的概率风险评价（PRA）工作,对比分析了PRA方法在不同载人航天项目中的应用效果。在此基础上,针对我国空间站工程的特点,初步提出了基于PRA的空间站工程量化风险评价方案与工作思路,对该方法在我国空间站实施所存在的问题进行了分析,并在方法规范、数据收集等方面提出了工作建议,为我国空间站量化风险评估工作提供技术支持。     

The New Horizons Pluto Kuiper Belt Mission: An Overview with Historical Context

NASA’s New Horizons (NH) Pluto–Kuiper Belt (PKB) mission was selected for development on 29 November 2001 following a competitive selection resulting from a NASA mission Announcement of Opportunity. New Horizons is the first mission to the Pluto system and the Kuiper belt, and will complete the reconnaissance of the classical planets. New Horizons was launched on 19 January 2006 on a Jupiter Gravity Assist (JGA) trajectory toward the Pluto system, for a 14 July 2015 closest approach to Pluto; Jupiter closest approach occurred on 28 February 2007. The ～400 kg spacecraft carries seven scientific instruments, including imagers, spectrometers, radio science, a plasma and particles suite, and a dust counter built by university students. NH will study the Pluto system over an 8-month period beginning in early 2015. Following its exploration of the Pluto system, NH will go on to reconnoiter one or two 30–50 kilometer diameter Kuiper Belt Objects (KBOs) if the spacecraft is in good health and NASA approves an extended mission. New Horizons has already demonstrated the ability of Principal Investigator (PI) led missions to use nuclear power sources and to be launched to the outer solar system. As well, the mission has demonstrated the ability of non-traditional entities, like the Johns Hopkins Applied Physics Laboratory (JHU/APL) and the Southwest Research Institute (SwRI) to explore the outer solar system, giving NASA new programmatic flexibility and enhancing the competitive options when selecting outer planet missions. If successful, NH will represent a watershed development in the scientific exploration of a new class of bodies in the solar system—dwarf planets, of worlds with exotic volatiles on their surfaces, of rapidly (possibly hydrodynamically) escaping atmospheres, and of giant impact derived satellite systems. It will also provide other valuable contributions to planetary science, including: the first dust density measurements beyond 18 AU, cratering records that shed light on both the ancient and present-day KBO impactor population down to tens of meters, and a key comparator to the puzzlingly active, former dwarf planet (now satellite of Neptune) called Triton which is in the same size class as the small planets Eris and Pluto.     

Launch and Early Operation of the MESSENGER Mission

On August 3, 2004, at 2:15 a.m. EST, the MESSENGER mission to Mercury began with liftoff of the Delta II 7925H launch vehicle and 1,107-kg spacecraft including seven instruments. MESSENGER is the seventh in the series of NASA Discovery missions, the third to be built and operated by The Johns Hopkins University Applied Physics Laboratory (JHU/APL) following the Near Earth Asteroid Rendezvous (NEAR) Shoemaker and Comet Nucleus Tour (CONTOUR) missions. The MESSENGER team at JHU/APL is using efficient operations approaches developed in support of the low-cost NEAR and CONTOUR operations while incorporating improved approaches for reducing total mission risk. This paper provides an overview of the designs and operational practices implemented to conduct the MESSENGER mission safely and effectively. These practices include proven approaches used on past JHU/APL operations and new improvements implemented to reduce risk, including adherence to time-proven standards of conduct in the planning and implementation of the mission. This paper also discusses the unique challenges of operating in orbit around Mercury, the closest planet to the Sun, and what specific measures are being taken to address those challenges.     

ACE Spacecraft

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) was responsible for the design and fabrication of the ACE spacecraft to accommodate the ACE Mission requirements and for the integration, test, and launch support for the entire ACE Observatory. The primary ACE Mission includes a significant number of science instruments - nine - whose diverse requirements had to be factored into the overall spacecraft bus design. Secondary missions for monitoring space weather and measuring launch vibration environments were also accommodated within the spacecraft design. Substantial coordination and cooperation were required between the spacecraft and instrument engineers, and all requirements were met. Overall, the spacecraft was kept as simple as possible in meeting requirements to achieve a highly reliable and low-cost design. This revised version was published online in June 2006 with corrections to the Cover Date.     

The New Horizons Spacecraft

The New Horizons spacecraft was launched on 19 January 2006. The spacecraft was designed to provide a platform for seven instruments designated by the science team to collect and return data from Pluto in 2015. The design meets the requirements established by the National Aeronautics and Space Administration (NASA) Announcement of Opportunity AO-OSS-01. The design drew on heritage from previous missions developed at The Johns Hopkins University Applied Physics Laboratory (APL) and other missions such as Ulysses. The trajectory design imposed constraints on mass and structural strength to meet the high launch acceleration consistent with meeting the AO requirement of returning data prior to the year 2020. The spacecraft subsystems were designed to meet tight resource allocations (mass and power) yet provide the necessary control and data handling finesse to support data collection and return when the one-way light time during the Pluto fly-by is 4.5 hours. Missions to the outer regions of the solar system (where the solar irradiance is 1/1000 of the level near the Earth) require a radioisotope thermoelectric generator (RTG) to supply electrical power. One RTG was available for use by New Horizons. To accommodate this constraint, the spacecraft electronics were designed to operate on approximately 200 W. The travel time to Pluto put additional demands on system reliability. Only after a flight time of approximately 10 years would the desired data be collected and returned to Earth. This represents the longest flight duration prior to the return of primary science data for any mission by NASA. The spacecraft system architecture provides sufficient redundancy to meet this requirement with a probability of mission success of greater than 0.85. The spacecraft is now on its way to Pluto, with an arrival date of 14 July 2015. Initial in-flight tests have verified that the spacecraft will meet the design requirements.     

The THEMIS Mission

The Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission is the fifth NASA Medium-class Explorer (MIDEX), launched on February 17, 2007 to determine the trigger and large-scale evolution of substorms. The mission employs five identical micro-satellites (hereafter termed “probes”) which line up along the Earth’s magnetotail to track the motion of particles, plasma and waves from one point to another and for the first time resolve space–time ambiguities in key regions of the magnetosphere on a global scale. The probes are equipped with comprehensive in-situ particles and fields instruments that measure the thermal and super-thermal ions and electrons, and electromagnetic fields from DC to beyond the electron cyclotron frequency in the regions of interest. The primary goal of THEMIS, which drove the mission design, is to elucidate which magnetotail process is responsible for substorm onset at the region where substorm auroras map (～10 R_E): (i) a local disruption of the plasma sheet current (current disruption) or (ii) the interaction of the current sheet with the rapid influx of plasma emanating from reconnection at ～25 R_E. However, the probes also traverse the radiation belts and the dayside magnetosphere, allowing THEMIS to address additional baseline objectives, namely: how the radiation belts are energized on time scales of 2–4 hours during the recovery phase of storms, and how the pristine solar wind’s interaction with upstream beams, waves and the bow shock affects Sun–Earth coupling. THEMIS’s open data policy, platform-independent dataset, open-source analysis software, automated plotting and dissemination of data within hours of receipt, dedicated ground-based observatory network and strong links to ancillary space-based and ground-based programs. promote a grass-roots integration of relevant NASA, NSF and international assets in the context of an international Heliophysics Observatory over the next decade. The mission has demonstrated spacecraft and mission design strategies ideal for Constellation-class missions and its science is complementary to Cluster and MMS. THEMIS, the first NASA micro-satellite constellation, is a technological pathfinder for future Sun-Earth Connections missions and a stepping stone towards understanding Space Weather.     

The ARTEMIS Mission

The Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon??s Interaction with the Sun (ARTEMIS) mission is a spin-off from NASA??s Medium-class Explorer (MIDEX) mission THEMIS, a five identical micro-satellite (hereafter termed ??probe??) constellation in high altitude Earth-orbit since 17 February 2007. By repositioning two of the five THEMIS probes (P1 and P2) in coordinated, lunar equatorial orbits, at distances of ??55?C65 R _E geocentric (??1.1?C12 R _L selenocentric), ARTEMIS will perform the first systematic, two-point observations of the distant magnetotail, the solar wind, and the lunar space and planetary environment. The primary heliophysics science objectives of the mission are to study from such unprecedented vantage points and inter-probe separations how particles are accelerated at reconnection sites and shocks, and how turbulence develops and evolves in Earth??s magnetotail and in the solar wind. Additionally, the mission will determine the structure, formation, refilling, and downstream evolution of the lunar wake and explore particle acceleration processes within it. ARTEMIS??s orbits and instrumentation will also address key lunar planetary science objectives: the evolution of lunar exospheric and sputtered ions, the origin of electric fields contributing to dust charging and circulation, the structure of the lunar interior as inferred by electromagnetic sounding, and the lunar surface properties as revealed by studies of crustal magnetism. ARTEMIS is synergistic with concurrent NASA missions LRO and LADEE and the anticipated deployment of the International Lunar Network. It is expected to be a key element in the NASA Heliophysics Great Observatory and to play an important role in international plans for lunar exploration.     

SOFIA: The next generation airborne observatory

The United States and German Space Agencies (NASA and DARA) are collaborating in plans for SOFIA — The Stratospheric Observatory for Infrared Astronomy. It is a 2.5 meter telescope to be installed in a Boeing 747 aircraft and operated at altitudes from 41,000 to 45,000 feet. It will permit routine measurement of infrared radiation absorbed by the atmosphere at lower altitudes, and observation of astronomical objects and transient events from anywhere in the world. The concept is based on 20 years of experience with NASA's Kuiper Airborne Observatory (KAO), which SOFIA would replace. SOFIA will complement the capabilities of other future space missions, and will enable scientists to make observations which would otherwise be made from space.     

美国下一代深空网发展计划探析

为适应未来美国深空探测的任务,此前美国NASA(National Aeronautics and Space Administration,国家航空航天局)对它的深空网发展的技术现状与能力进行了评估,梳理出了它们在未来深空任务中上下行通信速率需求,从而制定了美国下一代深空网的发展战略.针对此战略,梳理分析了美国深空网近年在深空通信导航领域开展的多项重大技术革新与演示验证试验,并从中剖析总结出了它的下一步的技术发展路线,期冀为我国深空测控网技术发展策略的制定提供参考.