Lithium-ion cell performance under environmental extremes

High energy density, lithium secondary cells are very attractive for use in many future military applications. However, a number of technical challenges remain. Specifically, the development and qualification of a system capable of withstanding the harsh environmental conditions encountered during normal and abnormal zones of operation. This paper focuses on the environmental extremes that the Eagle-Picher lithium-ion system has tested to date. Emphasis is placed on low temperature performance, high temperature performance, power capability, and cycle life at these extremes. Other areas including safety and environmental issues have also been investigated     

Evaluating the Wind-Induced Mechanical Noise on the InSight Seismometers

The SEIS (Seismic Experiment for Interior Structures) instrument onboard the InSight mission to Mars is the critical instrument for determining the interior structure of Mars, the current level of tectonic activity and the meteorite flux. Meeting the performance requirements of the SEIS instrument is vital to successfully achieve these mission objectives. Here we analyse in-situ wind measurements from previous Mars space missions to understand the wind environment that we are likely to encounter on Mars, and then we use an elastic ground deformation model to evaluate the mechanical noise contributions on the SEIS instrument due to the interaction between the Martian winds and the InSight lander. Lander mechanical noise maps that will be used to select the best deployment site for SEIS once the InSight lander arrives on Mars are also presented. We find the lander mechanical noise may be a detectable signal on the InSight seismometers. However, for the baseline SEIS deployment position, the noise is expected to be below the total noise requirement \(>97~\%\) of the time and is, therefore, not expected to endanger the InSight mission objectives.     

Hubble Space Telescope at twelve years of age

The Hubble Space Telescope was deployed from the Space Shuttle Discovery into a 380-mile high Earth orbit on April 25, 1990. It subsequently made outstanding astronomical discoveries with its 8-foot (2.4-meter) telescope and other scientific instruments. Critical to the successful observations was continuous availability of power from its solar arrays during sunlit periods, and from nickel-hydrogen batteries when the satellite was in the Earth's shadow. The adopted nickel-hydrogen batteries were carefully selected and tested to confirm their depth-of-discharge and operating temperature that delivered the longest life in charge/discharge cycling service. These batteries had a design life of 7 years. At 12 years after launch the Hubble batteries have delivered more charge/discharge cycles than any other batteries in low-Earth orbit. However, the Hubble batteries have been subjected to many unexpected stresses, and peculiar reductions in battery capacity have been observed. Battery replacement requires a costly trip to the Hubble Space Telescope by astronauts, so the remaining useful life of the batteries must be predicted. Already in four servicing missions, astronauts have replaced or modified optics, solar arrays, a power control unit, and various science packages. A fifth servicing mission is scheduled in 2004. This paper discusses battery charging hardware and software controls, history of battery events in Hubble, cell performance model and spare battery tests, and capacity walkdown.     

Bipolar nickel-metal hydride batteries for aerospace applications

Electro Energy Inc. (EEI) is developing high power, long life, bipolar nickel-metal hydride batteries for aerospace applications. Bipolar nickel-metal hydride designs allow for high energy and high power designs with a 25 percent reduction in both weight and volume as compared to prismatic and/or cylindrical Ni-MH designs. Utilizing a sealed wafer cell design EEI has demonstrated a 1.2 kW/kg power capability. Prototype designs have achieved 70 Wh/kg. Designs studies show 80 Wh/kg are achievable with EEI's state-of-the-art technology. The sealed wafer cell is the building block for EEI's high power and high voltage bipolar batteries making the assembly easy and significantly lower in cost. Satellite and aircraft batteries are being developed which provide high power and long life. Sealed cells now show excellent rate capability and life. Cells tested in a low earth orbit (LEO) cycle have reached 9000 cycles and continue on test. High power, bipolar battery designs are ideal in applications where using conventional aerospace battery technology would require excessive capacity; weight and volume, thereby reducing usable payload on the vehicle     

The Hy-StorTM battery

The Hy-Stor^TM Battery is a rechargeable battery being developed for electric vehicles and other large battery applications. The battery combines the high energy storage capability of metal hydride alloys with the high cycle life and discharge rate capabilities of nickel-hydrogen cells. It is a hybrid battery concept that offers potential performance, economic and safety advantages over other large battery technologies. Very recent developments indicate that much smaller batteries can also be produced to meet the needs of the portable computer and other portable electronic device markets. Initial tests demonstrated the ability of a metal hydride storage system to achieve high cycle life when absorbing hydrogen that was saturated with battery electrolyte solution and then passed through a purifier. Based on positive test results, a patent for the Hy-Stor battery was applied for and granted     

The Radiation Assessment Detector (RAD) Investigation

The Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) is an energetic particle detector designed to measure a broad spectrum of energetic particle radiation. It will make the first-ever direct radiation measurements on the surface of Mars, detecting galactic cosmic rays, solar energetic particles, secondary neutrons, and other secondary particles created both in the atmosphere and in the Martian regolith. The radiation environment on Mars, both past and present, may have implications for habitability and the ability to sustain life. Radiation exposure is also a major concern for future human missions. The RAD instrument combines charged- and neutral-particle detection capability over a wide dynamic range in a compact, low-mass, low-power instrument. These capabilities are required in order to measure all the important components of the radiation environment. RAD consists of the RAD Sensor Head (RSH) and the RAD Electronics Box (REB) integrated together in a small, compact volume. The RSH contains a solid-state detector telescope with three silicon PIN diodes for charged particle detection, a thallium doped Cesium Iodide scintillator, plastic scintillators for neutron detection and anti-coincidence shielding, and the front-end electronics. The REB contains three circuit boards, one with a novel mixed-signal ASIC for processing analog signals and an associated control FPGA, another with a second FPGA to communicate with the rover and perform onboard analysis of science data, and a third board with power supplies and power cycling or “sleep”-control electronics. The latter enables autonomous operation, independent of commands from the rover. RAD is a highly capable and highly configurable instrument that paves the way for future compact energetic particle detectors in space.     

InSight Mars Lander Robotics Instrument Deployment System

The InSight Mars Lander is equipped with an Instrument Deployment System (IDS) and science payload with accompanying auxiliary peripherals mounted on the Lander. The InSight science payload includes a seismometer (SEIS) and Wind and Thermal Shield (WTS), heat flow probe (Heat Flow and Physical Properties Package, HP³) and a precision tracking system (RISE) to measure the size and state of the core, mantle and crust of Mars. The InSight flight system is a close copy of the Mars Phoenix Lander and comprises a Lander, cruise stage, heatshield and backshell. The IDS comprises an Instrument Deployment Arm (IDA), scoop, five finger “claw” grapple, motor controller, arm-mounted Instrument Deployment Camera (IDC), lander-mounted Instrument Context Camera (ICC), and control software. IDS is responsible for the first precision robotic instrument placement and release of SEIS and HP³ on a planetary surface that will enable scientists to perform the first comprehensive surface-based geophysical investigation of Mars’ interior structure. This paper describes the design and operations of the Instrument Deployment Systems (IDS), a critical subsystem of the InSight Mars Lander necessary to achieve the primary scientific goals of the mission including robotic arm geology and physical properties (soil mechanics) investigations at the Landing site. In addition, we present test results of flight IDS Verification and Validation activities including thermal characterization and InSight 2017 Assembly, Test, and Launch Operations (ATLO), Deployment Scenario Test at Lockheed Martin, Denver, where all the flight payloads were successfully deployed with a balloon gravity offload fixture to compensate for Mars to Earth gravity.     

2001 Mars Odyssey Mission Summary

The 2001 Mars Odyssey spacecraft, now in orbit at Mars, will observe the Martian surface at infrared and visible wavelengths to determine surface mineralogy and morphology, acquire global gamma ray and neutron observations for a full Martian year, and study the Mars radiation environment from orbit. The science objectives of this mission are to: (1) globally map the elemental composition of the surface, (2) determine the abundance of hydrogen in the shallow subsurface, (3) acquire high spatial and spectral resolution images of the surface mineralogy, (4) provide information on the morphology of the surface, and (5) characterize the Martian near-space radiation environment as related to radiation-induced risk to human explorers. To accomplish these objectives, the 2001 Mars Odyssey science payload includes a Gamma Ray Spectrometer (GRS), a multi-spectral Thermal Emission Imaging System (THEMIS), and a radiation detector, the Martian Radiation Environment Experiment (MARIE). THEMIS and MARIE are mounted on the spacecraft with THEMIS pointed at nadir. GRS is a suite of three instruments: a Gamma Subsystem (GSS), a Neutron Spectrometer (NS) and a High-Energy Neutron Detector (HEND). The HEND and NS instruments are mounted on the spacecraft body while the GSS is on a 6-m boom. Some science data were collected during the cruise and aerobraking phases of the mission before the prime mission started. THEMIS acquired infrared and visible images of the Earth-Moon system and of the southern hemisphere of Mars. MARIE monitored the radiation environment during cruise. The GRS collected calibration data during cruise and aerobraking. Early GRS observations in Mars orbit indicated a hydrogen-rich layer in the upper meter of the subsurface in the Southern Hemisphere. Also, atmospheric densities, scale heights, temperatures, and pressures were observed by spacecraft accelerometers during aerobraking as the spacecraft skimmed the upper portions of the Martian atmosphere. This provided the first in-situ evidence of winter polar warming in the Mars upper atmosphere. The prime mission for 2001 Mars Odyssey began in February 2002 and will continue until August 2004. During this prime mission, the 2001 Mars Odyssey spacecraft will also provide radio relays for the National Aeronautics and Space Administration (NASA) and European landers in early 2004. Science data from 2001 Mars Odyssey instruments will be provided to the science community via NASA’s Planetary Data System (PDS). The first PDS release of Odyssey data was in October 2002; subsequent releases occur every 3 months.     

Atmospheric Science with InSight

In November 2018, for the first time a dedicated geophysical station, the InSight lander, will be deployed on the surface of Mars. Along with the two main geophysical packages, the Seismic Experiment for Interior Structure (SEIS) and the Heat-Flow and Physical Properties Package (HP³), the InSight lander holds a highly sensitive pressure sensor (PS) and the Temperature and Winds for InSight (TWINS) instrument, both of which (along with the InSight FluxGate (IFG) Magnetometer) form the Auxiliary Sensor Payload Suite (APSS). Associated with the RADiometer (RAD) instrument which will measure the surface brightness temperature, and the Instrument Deployment Camera (IDC) which will be used to quantify atmospheric opacity, this will make InSight capable to act as a meteorological station at the surface of Mars. While probing the internal structure of Mars is the primary scientific goal of the mission, atmospheric science remains a key science objective for InSight. InSight has the potential to provide a more continuous and higher-frequency record of pressure, air temperature and winds at the surface of Mars than previous in situ missions. In the paper, key results from multiscale meteorological modeling, from Global Climate Models to Large-Eddy Simulations, are described as a reference for future studies based on the InSight measurements during operations. We summarize the capabilities of InSight for atmospheric observations, from profiling during Entry, Descent and Landing to surface measurements (pressure, temperature, winds, angular momentum), and the plans for how InSight’s sensors will be used during operations, as well as possible synergies with orbital observations. In a dedicated section, we describe the seismic impact of atmospheric phenomena (from the point of view of both “noise” to be decorrelated from the seismic signal and “signal” to provide information on atmospheric processes). We discuss in this framework Planetary Boundary Layer turbulence, with a focus on convective vortices and dust devils, gravity waves (with idealized modeling), and large-scale circulations. Our paper also presents possible new, exploratory, studies with the InSight instrumentation: surface layer scaling and exploration of the Monin-Obukhov model, aeolian surface changes and saltation / lifing studies, and monitoring of secular pressure changes. The InSight mission will be instrumental in broadening the knowledge of the Martian atmosphere, with a unique set of measurements from the surface of Mars.     

气动磁镜聚变推进器的火星探测任务分析

将气动磁镜聚变概念拓展到空间推进器应用,分析了不同等离子体密度和氢推进剂质量流率下聚变推进器的比冲和推力变化范围,理论计算表明其比冲可达10 000 s以上,推力最高可达几十牛。在此基础上,进一步采用气动磁镜聚变推进器对地火转移任务进行了数值仿真。假设推进器初始质量为100 t,仿真结果表明:当飞行时间在282.42~639.76 d变化时,剩余质量从88.59 t提升至98.24 t。相关分析表明基于气动磁镜的聚变空间推进器通过调节比冲和推力组合方式,可以很好地满足未来火星载人和货运任务对飞行时间和有效载荷份额的不同需求,是未来高性能空间推进器发展的一种候选方案。      

ExoMars Trace Gas Orbiter (TGO) Science Ground Segment (SGS)

The ExoMars Trace Gas Orbiter (TGO) Science Ground Segment (SGS), comprised of payload Instrument Team, ESA and Russian operational centres, is responsible for planning the science operations of the TGO mission and for the generation and archiving of the scientific data products to levels meeting the scientific aims and criteria specified by the ESA Project Scientist as advised by the Science Working Team (SWT). The ExoMars SGS builds extensively upon tools and experience acquired through earlier ESA planetary missions like Mars and Venus Express, and Rosetta, but also is breaking ground in various respects toward the science operations of future missions like BepiColombo or JUICE. A productive interaction with the Russian partners in the mission facilitates broad and effective collaboration. This paper describes the global organisation and operation of the SGS, with reference to its principal systems, interfaces and operational processes.     

载人火星探测进展及其EDL过程GNC关键技术

随着火星探测技术的不断发展和探测任务的不断推进，载人火星探测在未来将会成为火星探测的重要手段。首先，回顾了无人火星探测任务的发展历程，对比分析了部分无人火星探测器进入、下降与着陆（EDL）过程的参数。然后，结合无人火星探测、载人月球探测和载人航天再入过程，梳理了载人火星探测的特点及需求，系统地总结了前苏联/俄罗斯和美国的载人火星探测研究进展以及技术储备。接着，归纳了载人火星探测的体系构成、集结方式和主要的技术挑战。最后，概括了载人火星EDL过程面临的难题，重点阐述了EDL的导航、制导与控制（GNC）关键技术。     

Reaching for the red planet

The distant shores of Mars were reached by numerous U.S. and Russian spacecraft throughout the 1960s to mid 1970s. Nearly 20 years have passed since those successful missions which orbited and landed on the Martian surface. Two Soviet probes headed for the planet in July, 1988, but later failed. In August 1993, the U.S. Mars Observer suddenly went silent just three days before it was to enter orbit around the planet and was never heard from again. In late 1996, there will be renewed activity on the launch pads with three probes departing for the red planet: 1) The U.S. Mars Global Surveyor will be launched in November on a Delta II rocket and will orbit the planet for global mapping purposes; 2) Russia's Mars '96 mission, scheduled to fly in November on a Proton launcher, consists of an orbiter, two small stations which will land on the Martian surface, and two penetrators that will plow into the terrain; and finally, 3) a U.S. Discovery-class spacecraft, the Mars Pathfinder, has a December launch date atop a Delta II booster. The mission features a lander and a microrover that will travel short distances over Martian territory. These missions usher in a new phase of Mars exploration, setting the stage for an unprecedented volley of spacecraft that will orbit around, land on, drive across, and perhaps fly at low altitudes over the planet.     

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.     

富锂锰基正极材料研究进展

随着社会发展,电动汽车、消费类(3C)电子产品、储能装置等对锂离子电池的能量密度提出了更高要求。富锂锰基正极材料具有高比容量(≈250 mAh/g)、高工作电压(≈3.6 V)及低成本等优势,有望成为下一代商用高比能电池正极材料。首次库仑效率低、倍率性能差、电压/容量衰减快等问题限制了富锂锰基正极材料的工程化应用。本文综述了富锂锰基正极材料的最新研究进展,重点从材料结构、电化学反应机理、失效机制和改性方法等几方面进行了阐述。研究表明,采用离子掺杂、表面包覆、晶体结构调控等技术,可显著改善富锂锰基正极材料的电化学性能。最后,对富锂锰基正极材料的发展方向进行了展望。     

Portable power source needs of the future Army-batteries and fuelcells

This paper describes the US Army's future needs for silent portable power in the area of batteries and fuel cells. These needs will continue to increase as a result of the introduction of newer types of equipment, the increasing digitization of the battlefield, and future integrated Soldier Systems. Current battery programs are aimed at improved, low-cost primary batteries, and rechargeable batteries with increased energy densities. The Army fuel cell program aimed at portable systems capable of the order of 150 W is also described     

Flexible piloted Mars missions using the TIHTUS engine

The present investigation points out the potential of continuously propelled spacecraft for piloted Mars missions and compares them to impulsive propulsion (chemical and nuclear thermal) and ballistic trajectories. Although the results are related to piloted Mars missions, the stated issues raised hold true for a broad range of space missions. It is demonstrated that the use of impulsive propulsion leads to inflexible missions and may result in long total mission durations. Meanwhile, the use of continuous electric propulsion not only guarantees short total mission durations of Mars missions with moderate masses but also results in highly flexible missions. These criteria can be met with a continuous electric propulsion system that provides a thrust level of 100 N and 3000 s of specific impulse. Great potential lies in electric hybrid thrusters. The high-power, two-stage hybrid plasma thruster TIHTUS is currently being developed at the Institute of Space Systems (IRS). Its technology including preliminary laboratory testing results are presented.     

Micro-power Amtec systems

There are several terrestrial applications for energy conversion systems with electrical outputs of a few volts in the power range from hundreds of milliwatts to a few watts. Potential applications include: power for instrumentation, communication and device actuation in severe or harsh environments, as well as a variety of low duty cycle monitoring tasks for the military. For cost and/or packaging reasons, some of these applications are severely heat source limited. In this paper we describe the development and performance of AMTEC systems capable of producing 0.3 to 0.5 watts from a radioisotope heat source limited to a total thermal output of less than 4 watts, The approach utilizes a new “chimney cell” design and a thermal insulation system consisting of a specialized multi-layer insulation (MLI) package in combination with fibrous insulation. The cell operates at 0.4 W_c to over 0.5 W_c with an input surface temperature of 700°C. Measurements of the thermal performance of a readily manufactured MLI package indicate that operation at these temperatures will be achievable with a total heat input of ~4 W_th     

Risk-based technology portfolio optimization for early space mission design

The successful design, development, and operation of space missions requires informed decisions to be made across a vast array of investment, scientific, technological, and operational issues. In the work reported in this paper, we address the problem of determining optimal technology investment portfolios that minimize mission risk and maximize the expected science return of the mission. We model several relationships that explicitly link investment in technologies to mission risk and expected science return. To represent and compute these causal and computational dependencies, we introduce a generalization of influence diagrams that we call inference nets. To illustrate the approach, we present results from its application to a technology portfolio investment trade study done for a specific scenario for the projected 2009 Mars MSL mission. This case study examines the impact of investments in precision landing and long-range roving technologies on the mission capability, and the associated risk, of visiting a set of preselected science sites. We show how an optimal investment strategy can be found that minimizes the mission risk given a fixed total technology investment budget, or alternatively how to determine the minimum budget required to achieve a given acceptable mission risk.