Scheduled System Maintenance:
Some services will be unavailable Sunday, March 29th through Monday, March 30th. We apologize for the inconvenience.
By Topic

Aerospace Conference Proceedings, 2000 IEEE

Date 25-25 March 2000

Go

Filter Results

Displaying Results 1 - 25 of 68
  • 2000 IEEE Aerospace Conference [front matter]

    Publication Year: 2000 , Page(s): 0_1 - xxviii
    Save to Project icon | Request Permissions | PDF file iconPDF (1928 KB)  
    Freely Available from IEEE
  • TechSat 21: formation design, control, and simulation

    Publication Year: 2000 , Page(s): 19 - 25 vol.7
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    The satellite cluster approach to space missions requires science and technology advances in several key areas. Among these challenges is understanding the dynamics of satellites in close proximity to each other so that a formation can be intelligently designed, controlled, and simulated. An overview of on-going research in this area under the TechSat 21 program along with preliminary findings is provided. Included in this overview is the recent progress made in the design of formations including designs for circular formations, projected circular formations, and J2 invariant formations. Strategies for formation control are presented as well as the baseline design for the TechSat 21 propulsion system. Fuel expenditure is estimated for various formations using different control strategies. The TechSat 21 mission requires relative position knowledge between satellites to the millimeter level while the radar is transmitting and receiving; concepts for meeting this requirement are also presented. In order to facilitate mission planning and gain confidence in mission success, the Air Force Research Laboratory (AFRL) is building an end to end simulation testbed for the TechSat 21 mission. An overview of the testbed design and functionality is provided. Focus is centered on the dynamics and control module of the testbed. The dynamics and control module utilizes high fidelity orbit propagation as the basis of the simulation of the formation dynamics. Through this simulation control algorithms, relative navigation techniques, and the effects of errors in initial conditions and control forces are investigated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nanosatellite mothership-daughtership experiment by Japanese universities

    Publication Year: 2000 , Page(s): 109 - 115 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    We have begun a feasibility study to build a small satellite in the 3 kg mass range (nanosatellite), funded by NASDA. This scale of satellite is a challenging target for nanosatellite development. In this study, we plan to build several key technologies such as small reaction wheel, small electric propulsion, docking mechanism, electrical recharging devices and software for three axis attitude control by using image processing. Future space experiments are also proposed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Elliptical orbit constellations-a new paradigm for higher efficiency in space systems?

    Publication Year: 2000 , Page(s): 27 - 35 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    Several systems are being developed for satellite cellular telephone use. Examples are Iridium, Globalstar, ICO, and ELLIPSO. Systems designers seem to prefer sub-synchronous multi-satellite arrays over geostationary satellites as they can more easily communicate with small low-power handheld cellular telephones, and they also have less signal latency (time delay). The flexibility of the elliptic orbit allows a biasing of earth coverage towards a given latitude. Increased coverage is obtained by placing apogees in a stable orbit over a preferred latitude. If the orbit is both elliptical and sun-synchronous, it can also be biased towards a given (local) time of day. With apogees appearing during daytime, greater capacity is ensured during the peak usage hours for telephone communications. Tailored elliptical-orbit constellations may well become the paradigm for many of these new telecommunications space systems. Lower cost elliptic-orbit constellations, with fewer satellites, may well prove more profitable than circular arrays for many other space applications, as well View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Spacecraft and mission design of the `Aeneas' Mercury orbiter using methods of concurrent engineering

    Publication Year: 2000 , Page(s): 341 - 355 vol.7
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1392 KB)  

    Over the course of ten weeks, nine college students collaborated to design a mission to Mercury. The Aeneas Mercury Orbiter was designed using new methods of concurrent engineering with the help of NASA's Jet Propulsion Laboratory. Aeneas will deliver a significant scientific payload, including visual cameras, an altimeter, laser and infrared spectrometers, and magnetometers, to a difficult target to return information about the little known planet Mercury. After a three-year trajectory including a Venus flyby, the spacecraft will reach Mercury and begin a 300 km circular polar orbit. Expected science return includes visual mapping of at least 95% of the surface, mapping of the Mercurian magnetic field, and partial determination of the planetary surface. The Aeneas Mercury Orbiter will enhance current knowledge of the solar system and its formation through the study of Mercury View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Attitude determination of small spinning spacecraft using three axis magnetometer and solar panels data

    Publication Year: 2000 , Page(s): 127 - 133 vol.7
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    An algorithm for attitude determination of a spinning spacecraft in Low Earth Orbit using three axis magnetometer and solar panels data is proposed. With this algorithm, the solar panels necessary for power generation are also used as a sensing system for attitude determination. The algorithm employs voltage, current and temperature measurements from all of the solar panels to reconstruct the sun direction, which is based on an accurate solar panels mathematical model and requires some data filtering, according to the motion of spinning spacecraft. The sun direction determination accuracy is improved by exploiting a known relationship between sun and magnetic field motion in the spacecraft reference frame. It is shown, by numerical simulation, that the spacecraft attitude can be determined within a few degrees of accuracy in a reasonable time (on the order of one min), which is usually adequate for small, low cost, missions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Triana Mission-next generation systems architecture ready for flight

    Publication Year: 2000 , Page(s): 277 - 285 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1140 KB)  

    NASA's Triana Mission is the first to take full advantage of the powerful capabilities offered by modern digital electronics and comprehensive software architecture. Not only is the performance of these miniature systems well beyond that of their bulky predecessors, but the time to configure them for a particular mission has been dramatically reduced as well. As a result, the cost of these implementations is just a fraction of previous missions. This deep space Earth and solar science platform touts highly autonomous, 3-axis stabilized performance for only $77M. In just 21 months time, the Triana observatory will have gone from conceptual design to flight readiness, being launched by the Space Transportation System (STS) in early 2001. After deployment in LEO, Triana will boost itself into a trajectory to the L1 libration point approximately 1.5 million kilometers from Earth. There it will make observations of space weather, Earth climatic behavior, and whole Earth radiometry. The budget includes the development of the spacecraft, 5 scientific instruments, deployable booms and solar arrays, a hydrazine propulsion module, a new upper stage system based on the Thiokol Star-48 kick motor, all that goes with launching from the manned STS, and 2 years of continuous mission operations and scientific data analysis. This paper describes the novel approach taken to implement this mission, commenting on the technical architecture as well as the processes used. Experiences to date on the development status are also discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Issues in control of space membrane/inflatable structures

    Publication Year: 2000 , Page(s): 411 - 414 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    Membrane/inflatable structures for space applications hold great promise. Their reduced launch mass and stowed volume suggests the possibility of large aperture antenna and reflectors for increased resolution, and solar sails and shades that can span great distances. However, their extreme flexibility provides for significant challenge with regard to the control of their deployment and shape. This paper reviews many of the issues involved with the control of membrane/inflatables for space applications, and suggests directions for future research activities View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Attached inflatable ballute for spacecraft deceleration

    Publication Year: 2000 , Page(s): 421 - 427 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    An innovative, lightweight method, using an inflatable ballute, to increase aerobraking drag and potentially reduce the size of spacecraft (S/C) payloads, is presented. Computational fluid dynamics (CFD) calculations (using the entry environment and trajectory for a Mars 03 entry vehicle) were performed for a generic torroidal-shaped ballute, attached to a baseline S/C configuration. Results from the CFD analysis indicate a maximum heating intensity of 35 W/cm2 occurred at the aeroshell-ballute joint interface. A thermal model was developed, incoporating the CFD results, which was used to design a tailored thermal protection system (TPS). The TPS consisted of a multilayered configuration for the higher heat flux area and a fewer-layer configuration for areas with lower heat flux. The total mass of the tailored TPS for the entire ballute surface was about 43% lighter than a more traditional monolithic heat shield design. Lockheed Martin, along with L'Garde, Inc., designed and fabricated a subscale model of an inflatable ballute attached to a rigid aeroshell, to demonstrate ballute bladder stowage and inflation mechanics View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electron beam enabled surface composition, charge, and adsorbed gas determination [of Mars]

    Publication Year: 2000 , Page(s): 519 - 537 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1672 KB)  

    The Human Exploration and Development of Space Roadmap calls for Human Missions to Mars and other planets in the 2010 to 2023 timeframe. This paper describes a proposal written in response to the Announcement of Opportunity (A099-HEDS-01) for definition studies preparing for the human exploration of Mars. Specifically, the proposal addressed the call for the development of innovative instrument concepts aimed at studying soil, dust, and environmental interactions for 2005 Mission Opportunities. The objective of the proposed study was to determine the feasibility, under simulated Martian ambient conditions, of a suite of miniature instruments performing correlated measurements of sample surfaces. A novel Atmospheric Electron X-ray Spectrometer (AEXS), an optical microscope capable of producing low magnification images, an electrometer, and a fiber optic oxygen sensor fitted with a resistive heater comprised the proposed instrument suite View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimizing science return from Titan aerial explorers

    Publication Year: 2000 , Page(s): 493 - 499 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (692 KB)  

    This paper explores the scientific challenges of post-Cassini exploration of Titan, Saturn's giant, hazy moon. In particular, the scientific objectives are addressed, and the vehicle types that might be most appropriate are considered, paying particular attention to the energy required for mobility, for acquiring data, and downlinking it to Earth, and to the rate at which science data can be acquired. While many mission types are possible, a helicopter mission, flying only 10% of the time, may offer the best overall scientific return View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Formation flying mission for the UW Dawgstar satellite

    Publication Year: 2000 , Page(s): 117 - 125 vol.7
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB)  

    An overview of a small satellite (<15 kg) being designed and built by the University of Washington for multiple small satellite formation flying is presented. The Dawgstar nanosatellite is one of three satellites being built for a three satellite formation experiment termed ION-F, and is unique in its propulsive capability. The satellites will also utilize an integrated GPS/cross-link system to allow fast and accurate update of relative satellite positions. The three satellites are each a part of the AFRL/DARPA/NASA University Nanosatellite program, which addresses building unique small satellites and developing coordination experiments for space. The satellites are being designed for a Space Shuttle launch in January 2002 View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hard-real-time resource management for autonomous spacecraft

    Publication Year: 2000 , Page(s): 673 - 677 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    This paper describes tickets, a computational mechanism for hard-real-time autonomous resource management. Autonomous spacecraft control can be considered abstractly as a computational process whose outputs are spacecraft commands. In order to make the engineering of such systems tractable, these computations an usually organized as multiple parallel threads of control. It is sometimes necessary, particularly in emergency situations, for one thread of control not only to issue certain commands, but to actively prevent the issuing of other commands by other threads of control. Tickets are software objects that act as intermediaries between control processes and low-level commands. In order to gain access to a low-level command a control process must be in possession of a valid ticket for that command. Tickets can be invalidated in constant time. This allows hard-real-time guarantees of performance for denying access to a particular low-level command or set of commands View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multi-spacecraft trajectory optimization and control using genetic algorithm techniques

    Publication Year: 2000 , Page(s): 99 - 108 vol.7
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (876 KB)  

    This paper presents an approach for multi-spacecraft trajectory planning, optimization and control. Maneuver planning as a global optimization problem is solved using genetic algorithms (GA). Methods were devised to reduce the dimensionality of the decision space, yet retain adequate generality of maneuver possibilities. A compact formulation based on thruster switching-times was used for generic point-to-point spacecraft maneuvers. Optimal control is implicitly satisfied by “bang-coast-bang” actuation schemes. Maneuver profiles, including line-of-sight and orthogonal collision avoidance, were developed. A GA optimizer selects the optimal parameter set for each scenario. Simulation case studies were performed for 2, 3 and 5-spacecraft formation initialization tasks. Objective criteria used in the evaluation function included: endpoint errors; collision avoidance; path lengths; maneuvering times; fuel usage and equalization. In all cases, a nominal GA computed feasible trajectories. Objective criteria trade-offs were demonstrated by selective weighting. Ongoing work includes multi-objective optimization of multiple spacecraft trajectories using niched-Pareto genetic algorithms View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Aerobots in planetary exploration

    Publication Year: 2000 , Page(s): 547 - 555 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    Robotic balloons (aerobots) may significantly change the future of in situ planetary exploration. On Mars, the aerobots can fill the gap in resolution/coverage between the orbiters and rovers. Powered aerobots (airships) can make controlled global flights for high-resolution radar, visible, infrared, thermal, magnetic, and neutron mapping; they can be used for deployment of network of surface stations. Tethered balloons could provide ultra high-resolution imaging of local areas for navigation of rovers and data relay to the main lander station. Solar-heated balloons could be used as low atmospheric decelerators for low-speed landing. In the more distant future the airships could be used for human transportation. On Venus, aerobots may serve as the scientific platforms for the in situ atmospheric measurement and for study of atmospheric circulation. They can be used to drop imaging and deep sounding probes at sites of interest and to acquire and relay high-rate imaging data. Balloons technology is enabling for any Venus surface sample return mission. On Titan, powered aerobots can perform long duration low-altitude global flight for surface mapping, in situ atmospheric measurements, deployment of landers and rovers for in situ surface studies. Aerobots can also be used for long-duration atmospheric studies of the outer planets. Aerobot technologies have become more mature in recent years due to progress in development of envelope materials, and envelope design driven primarily by stratospheric applications. Technologies for deployment and inflation, navigation, control, communication and power are also developing rapidly in response to planetary applications View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distributed computing on Emerald: a modular approach for robust distributed space systems

    Publication Year: 2000 , Page(s): 211 - 222 vol.7
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (920 KB)  

    A modular, distributed bus architecture potentially offers significant advantages throughout a satellite's lifecycle. Specifically this architecture enables:- During ground integration: incremental integration of subsystems even if crucial parts, such as the CPU, are delayed; using the Internet for “virtual integration” between remote locations. On-orbit: sharing resources within a satellite; no cost redundancy, including directly commanding subsystem through the communication subsystem, should the CPU fail. And when extended to a multi-satellite mission: multiple satellites to be inter-connected as a single “virtual bus”; autonomous reallocation and sharing of resources across satellites, including adapting to subsystem failures; autonomous experiment coordination. This paper explores the benefits and challenges of single and multi-satellite distributed architectures and the unique strategies they enable. The data architecture for the two-satellite Emerald mission is used as an example. Emerald uses an I2C serial bus to connect PICmicro based “smart” subsystems View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Titech micro-satellite model: CanSat for sub-orbital flight

    Publication Year: 2000 , Page(s): 135 - 142 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (992 KB)  

    We had the opportunity to launch prototype CanSats, small satellites the size of a soft drink can, on an amateur rocket in September 1999 (ARLISS: A Rocket Launched International Student Satellites). We developed four CanSats for ARLISS: CanSat Type1 and Type2 missions are experiments of two different types of mechanisms for tether applications, CanSat Type3, is a communications and electronic devices test satellite, and CanSat Type4 is equipped with CCD camera and transmits video images. The development period is less than 5 months. In this paper, we describe 4 CanSats missions, subsystem designs including the ground station and the results of ARLISS experiments View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The MUSES-CN nanorover mission and related technology

    Publication Year: 2000 , Page(s): 287 - 295 vol.7
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (956 KB)  

    Recent advances in microtechnology and mobile robotics have made it feasible to create extremely small automated or remote-controlled vehicles which open new application frontiers. One of these possible applications is the use of nanorovers (robotic vehicles with a mass of order 1 kg or less) in planetary exploration. NASA and Japan's ISAS are cooperating on the first mission to collect samples from the surface of an asteroid and return them to Earth for in-depth study. The ISAS MUSES-C mission will be launched on a Japanese launch vehicle in July 2002 from Japan toward a redezvous with the asteroid 1989ML in September 2003. A NASA-provided nanorover will conduct in-situ measurements on the surface. Asteroid samples will be returned to Earth by MUSES-C via a parachute-borne recovery capsule in June 2006. This paper describes the rover being created for this mission and related technology developments View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Venus sample return. A hot topic

    Publication Year: 2000 , Page(s): 473 - 484 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1488 KB)  

    Within the Solar System, Venus presents a set of unique challenges to obtaining samples and returning them to Earth. High temperatures, a thick corrosive atmosphere and poorly characterized terrain are some obvious examples. Our only knowledge of the surface and atmosphere is from Radar images and the data from Soviet probes. A point design now exists for a single launch mission to return Venusian samples massing about 100 g. This paper discusses this mission, addressing the science return, how some of Venus' attributes can be used to advantage and what technologies will be needed to make this mission a reality. It also explores possible future directions to make the mission more affordable View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Software architecture themes in JPL's Mission Data System

    Publication Year: 2000 , Page(s): 259 - 268 vol.7
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1132 KB)  

    The rising frequency of NASA mission launches has highlighted the need for improvements leading to faster delivery of mission software without sacrificing reliability. In April 1998 Jet Propulsion Laboratory (JPL) initiated the Mission Data System (MDS) project to rethink the mission software lifecycle-from early mission design to mission operation-and make changes to improve software architecture and software development processes. As a result, MDS has defined a unified flight, ground, and test data system architecture for space missions based on object-oriented design, component architecture, and specific frameworks. This paper describes architectural themes shaping the MDS design and how they help meet objectives for faster, better, cheaper mission software View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Gossamer Initiative

    Publication Year: 2000 , Page(s): 429 - 438 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1028 KB)  

    The Gossamer Spacecraft Initiative is a new NASA program to begin long-range development of enabling technologies for very large, ultra-lightweight structures and apertures. Large apertures include optical, infrared and submillimeter telescopes, “photon buckets” for optical communications and “non-coherent” imaging, solar concentrators, and radio frequency antennas. Developments in large ultra-light structures will be focused on one of their most challenging applications-solar sails. Sail structures will include both 3-axis stabilized and spinning. Gossamer spacecraft technology will eventually allow NASA to undertake bold new missions of discovery, such as searching for the signs of life on planets orbiting nearby stars, and sailing through space on beams of light to places beyond our solar system View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Satellite cluster command and control

    Publication Year: 2000 , Page(s): 49 - 54 vol.7
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    For many applications a distributed cluster of cooperating satellites offers distinct advantages over satellites functioning alone. These include optimization of mission performance and increased fault tolerance. Although there are many benefits, commanding and controlling a large cluster of cooperating satellites poses several challenges. These include how satellites in the cluster maintain knowledge of the other satellites in the cluster in order to react to contingencies and optimize resources, how to treat the cluster as a single virtual satellite in terms of ground command and control, and how to distribute resources across the cluster. The Space Vehicles Directorate of the Air Force Research Laboratory (AFRL) is investigating many of these challenges through prototype development for the AFRL TechSat-21 program. This paper presents the challenges posed in cluster command and control and discusses several methods being developed to address those challenges View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A reconfigurable multifunctional architecture approach for next-generation nanosatellite design

    Publication Year: 2000 , Page(s): 185 - 193 vol.7
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1008 KB)  

    This paper proposes a new nanosatellite design paradigm called Reconfigurable Multifunctional Architecture (RMA). The RMA concept enables dramatic cost savings and economies of scale, and is compatible with numerous nanosatellite missions. In the RMA concept, functional modules are used to implement higher-level mission-specific functions (e.g., propulsion). Subsystem functions are distributed across multiple Multifunctional Structural Units (MSUs). Each MSU is a structural “building block” that contains embedded electronics, wiring, thermal control, and selected discrete components. Traditional subsystem boundaries (and their associated penalties) no longer exist. Design customization is permitted at three levels: adding functional modules as required, swapping/adding MSUs, and replacing selected components on a MSU. The RMA concept offers dramatic weight savings by eliminating black boxes, bulky wire harnesses, and connectors; increases overall system reliability; enables rapid design reconfiguration; streamlines the integration and test process; and facilitates inexpensive mass production View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Innovative methods for placing small payloads in space

    Publication Year: 2000 , Page(s): 167 - 175 vol.7
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (944 KB)  

    There has been a significant increase in demand for testing, qualification and evaluation of satellite components in space by means of secondary rides on primary payloads and launch vehicle structures. A critical category of secondary payload developers exists that have needs for space launch services: the new/innovative developers of space components that do not have the knowledge, resources, or contacts necessary to successfully test their technologies in space. Schafer Corporation and Stanford University's Space Systems Development Laboratory (SSDL) have collaborated on the investigation of new, evolutionary and revolutionary approaches to low-cost space technology demonstrations. This paper describes potential approaches for implementing proactive rideshare brokering services that span all communities and potential customers. Proactive rideshare brokering is a new approach, but for the most part, adopting proven practices from the international marketplace will make advances. The paper draws conclusions by comparing what is working in the international space community versus what the current practices are in the U.S. The recommendations reflect a reduced timeline approach that acknowledges the close coupling between the technology base, the space systems industry, infrastructure and educational processes View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Innovative balloon buoyancy techniques for atmospheric exploration

    Publication Year: 2000 , Page(s): 397 - 402 vol.7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (868 KB)  

    Until quite recently, the only practical means to control balloon buoyancy, and thus altitude, required consuming large amounts of fuel or the limited venting of helium balloons and/or dropping of ballast. Recently at JPL, novel, long-life, balloon buoyancy techniques have been developed that for the first time allow balloons to float in the primarily hydrogen atmospheres of Jupiter, Saturn, Uranus, and Neptune (using ambient fill-gas) and, by using energy sources, allow multiple controlled on Venus (using atmospheric temperature differences), Mars (using solar heat), Titan (using Radioisotope Thermal Generator (RTG) heat), and Earth (using planet radiant heat). A test program has been initiated at JPL to confirm these basic new buoyancy principles. The Earth balloon work will be performed in conjunction with Goddard Space Flight Center (GSFC) to apply these techniques to increase controllability of scientific terrestrial balloons. These novel techniques may enable many exciting, yet economical and practical scientific balloon missions to seven planets and one moon in our own solar system, and, in fact, may eventually be the basis for in situ exploration of planets in other solar systems View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.