GANDER — a constellation of microsats designed to reduce risks at sea

If the community of users of satellite observations of the marine environment is to be widened to include those involved in daily commercial operations then special-purpose systems should be designed to meet their everyday requirements. For the last two decades the major customer for the observations from a succession of single satellite missions has been the community of marine scientists. A low-cost constellation of microsats that will allow information on sea state to be delivered to ships in real time is described.     

Omicron space habitat—research stage II

The design presented in this paper is in response to the revolution in private space activities, the increasing public interest in commercial flights to space and the utilization of structures such as space hotels or private orbital habitats. The baseline for the Omicron design concept is the Russian Salyut derived space station module. Salyut was the first space station to orbit the Earth. Its unique design and technical features were what made the development of space stations Salyut 1–7, MIR and the International Space Station (ISS) Zwezda service module possible. Due to its versatility and the reliable operating launch vehicle Proton, this space module series has the potential to be adapted for space hotel development. This paper proposes a conceptual design of the space habitat called Omicron, with particular focus on interior design for the microgravity environment. The Omicron concepts address the needs of space tourism with a strong emphasis on the safety and comfort of the spaceflight participants. The Omicron habitat supports three inhabitants in nominal conditions (e.g., two passengers and one astronaut). The habitat provides a flexible interior, facilities and spaces dynamically transforming in order to accommodate various types of activities, which will be performed in an organically formed interior supporting spatial orientation and movement in microgravity. The future development potential of Omicron is also considered. The baseline version is composed solely of one rigid module with an inverted cupola for observations. An alternative version offers more space using an inflatable structure. Finally, a combination of multiple Omicron modules enables the creation of a larger orbital habitat. The Omicron's subsystems support a few days visit by trained passengers. The transport to the habitat would be provided e.g., by the Soyuz TMA spacecraft carried by the Soyuz launch vehicle in the early stage of Omicron's development, before a fully reusable spacecraft would be available.     

使用高温粘方法修理和替换内衬密封条

在大多数商用飞机使用高效率的涡轮风扇喷气发动机时代到来的同时,飞机维修人员也面临着新的挑战,即如何修理和替换发动机上的耐磨损内衬密封条,也称风扇轨道。装在涡轮喷气飞机上涡扇发动机,一般其装在前部的风扇由它位于初级涡轮后面的二级涡轮驱动,它的作用是增加发动机中心的气流,以减少燃油消耗并提供更大的推力。为了得到涡轮风扇发动机提供的高空气通过率,必须迫使尽量多的空气通过风扇,因此需要使风扇顶端到风扇罩内核之间的间隙尽可能地小。如果风扇叶片和发动机内罩都是金属结构,由温度升高或离心力引起的任何叶片长度膨胀都可能…     

The first SETI observations with the Allen telescope array

The Search for ExtraTerrestrial Intelligence (SETI) finally has its own full-time telescope. The Allen telescope array (ATA) in Northern California was dedicated on October 11, 2007. This array, which will eventually be composed of 350 small radio antennas, each 6.1 m in diameter, is being built as a partnership between the SETI Institute and the University of California Radio Astronomy Laboratory. Last October, Paul G. Allen (who provided the funds for the technology development and the first phase of array construction) pushed a silver button and all 42 antennas of the current ATA-42 slewed to point in the direction of the distant galaxy M81. Specialized electronic backend detectors attached to the ATA began making a radio map of that galaxy and simultaneously began SETI observations of HIP48573, a G5V star near M81 on the sky and a distance of 264 light years from Earth. The Allen telescope array will greatly improve the speed of conducting SETI searches over the next few decades, and it will allow a suite of different search strategies to be undertaken. This paper summarizes some of the earliest SETI observations from the array, and describes the search strategies currently being planned.     

On uncertainties in carbon flux modelling and remotely sensed data assimilation: The Brasschaat pixel case

Uncertainty on carbon fluxes is determined by the uncertainties of ecosystem model structure, data and model parameter uncertainties and the temporal and spatial inaccuracy of the input data retrieval. The objective of this paper is to understand the error propagation and uncertainty of evaporative fraction (EF), soil moisture content (SMC) and water limited net ecosystem productivity (NEP). In this respect, C-Fix and spaceborne remote sensing are used for the ‘Brasschaat’ pixel. A simple model based on error theory and a Monte-Carlo approach are used. Different error scenarios are implemented to assess input uncertainty on EF, SMC and NEP as estimated with C-Fix.     

Compressive and Rarefactive Electron-Acoustic Solitons and Double Layers in Space Plasmas

Space observations in several near-Earth environments have revealed the presence of positive-potential, large-amplitude electrostatic structures, associated with high-frequency disturbances, and indicative of electron dynamics. Earlier models proposed in terms of electron-acoustic solitary waves in a two-electron-temperature plasma were inadequate, because only negative potential structures could thus be obtained, whereas the observations point to positive potential structures. In this paper, it is shown that the theoretical restriction to negative potential solitons is due to the neglect of the inertia of the hot electrons, implicitly or explicitly assumed in previous papers. If hot electron inertia is retained, however, there exists a parameter range where positive potential solitary waves are formed, which can have important consequences for the re-interpretation of several astrophysical phenomena involving two-electron-temperature plasmas. PACS: 52.35.Mw, 52.35.Sb, 96.50.Ry     

Gravity Recovery and Interior Laboratory (GRAIL): Mapping the Lunar Interior from Crust to Core

The Gravity Recovery and Interior Laboratory (GRAIL) is a spacecraft-to-spacecraft tracking mission that was developed to map the structure of the lunar interior by producing a detailed map of the gravity field. The resulting model of the interior will be used to address outstanding questions regarding the Moon’s thermal evolution, and will be applicable more generally to the evolution of all terrestrial planets. Each GRAIL orbiter contains a Lunar Gravity Ranging System instrument that conducts dual-one-way ranging measurements to measure precisely the relative motion between them, which in turn are used to develop the lunar gravity field map. Each orbiter also carries an Education/Public Outreach payload, Moon Knowledge Acquired by Middle-School Students (MoonKAM), in which middle school students target images of the Moon for subsequent classroom analysis. Subsequent to a successful launch on September 10, 2011, the twin GRAIL orbiters embarked on independent trajectories on a 3.5-month-long cruise to the Moon via the EL-1 Lagrange point. The spacecraft were inserted into polar orbits on December 31, 2011 and January 1, 2012. After a succession of 19 maneuvers the two orbiters settled into precision formation to begin science operations in March 1, 2012 with an average altitude of 55 km. The Primary Mission, which consisted of three 27.3-day mapping cycles, was successfully completed in June 2012. The extended mission will permit a second three-month mapping phase at an average altitude of 23 km. This paper provides an overview of the mission: science objectives and measurements, spacecraft and instruments, mission development and design, and data flow and data products.     

Balloon-borne air traffic management (ATM) as a precursor to space-based ATM

The International Space University—Balloon Air traffic control Technology Experiment (I-BATE¹) has flown on board two stratospheric balloons and has tracked nearby aircraft by receiving their Automatic Dependent Surveillance-Broadcast (ADS-B) transmissions. Air traffic worldwide is facing increasing congestion. It is predicted that daily European flight volumes will more than double by 2030 compared to 2009 volumes. ADS-B is an air traffic management system being used to mitigate air traffic congestion. Each aircraft is equipped with both a GPS receiver and an ADS-B transponder. The transponder transmits an equipped aircraft's unique identifier, position, heading, and velocity once per second. The ADS-B transmissions can then be received by ground stations for use in traditional air traffic management. Airspace not monitored by these ground stations or other traditional means remains uncontrolled and poorly monitored. A constellation of space-based ADS-B receivers could close these gaps and provide global air traffic monitoring. By flying an ADS-B receiver on a stratospheric balloon, I-BATE has served as a precursor to a constellation of ADS-B-equipped Earth-orbiting satellites. From the ～30 km balloon altitude, I-BATE tracked aircraft ranging up to 850 km. The experiment has served as a proof of concept for space-based air traffic management and supports a technology readiness level 6 of space-based ADS-B reception.     

Naval EarthMap Observer (NEMO) program and the Naval Space Science and Technology Program Office

In February 1997 the Chief of Naval Research chartered the Naval Space Science and Technology (S&T) Program Office, at the Office of Naval Research, to operate as the central point of contact for the Department of the Navy's (DON's) S&T activities in space. The Office was chartered to enhance the DON's space efforts through interdepartmental integration and linkage with external Department of Defense (DOD) commands and government agencies. The Office's goal is to optimize a plan for S&T coherency, synergy, and relevancy to effect technology transition to the DON's Systems Commands or Program Executive Offices (PEO's) while developing an investment strategy that accommodates and leverages the commonality of commercial and consumer thrust areas and products.

This paper will focus on the “Flagship” Naval Space S&T Program, the Naval EarthMap Observer (NEMO) Program, as one example of how the Office is executing its mission. It will discuss how, through NEMO, the Navy is able to leverage commercial industry and other US government agency requirements and resources to meet unique Naval needs. Finally, the paper will discuss the specifics of NEMO, the Navy's roles and responsibilities and how the Navy will use NEMO in its mission to characterize the littoral regions of the world.

Through the NEMO satellite system, the Navy will develop a large hyperspectral imagery database which will be used to characterize and model the littoral regions of the world. NEMO will provide images using its Coastal Ocean Imaging Spectrometer (COIS) Instrument along with a co-registered 5m Panchromatic Imager (PIC). With 210 spectral channels over a bandpass of 0.4 to 2.5μm and very high signal-to-noise ratio (SNR), the COIS instrument is optimized for the low reflectance environment of the littoral region. COIS will image over a 30km wide swath with a 60m Ground Sample Distance (GSD), and can image at a 30m GSD with ground motion compensation. A 10:30am, sun-synchronous circular orbit of 605km enables continuous repeat coverage of the whole earth. A unique aspect of the system is the spectral feature extraction and data compression software algorithm developed by the Naval Research Laboratory (NRL) called the Optical Real-Time Spectral Identification System (ORA-SIS). ORASIS employs a parallel, adaptive hyperspectral method for real-time scene characterization, data reduction, background suppression, and target recognition. The use of ORASIS is essential for management of the massive amounts of data expected from the NEMO HSI system, and for development of Naval products. Specific Naval products include bathymetry, water clarity, bottom type, atmospheric visibility, bioluminescence, beach characterization, under-water hazards, total column atmospheric water vapor, and detection and mapping of sub-visible cirrus. Demonstrations of timely downlinks of real-time hyperspectral imagery data to the Naval warfighter are also being developed. The NEMO satellite is planned for launch in mid-2000 followed by an operational period of 3 to 5 years.     

Towards the automated operations of large distributed satellite systems. Part 2: Classifications and tools

Recent developments have seen a trend towards larger constellations of spacecraft, with some proposals featuring constellations of more than 10.000 satellites. While similar concepts for large constellations already existed in the past, traditional satellite deployments hardly ever feature groups of more than 100 satellites. This trend towards considerably larger satellite numbers originates from non-traditional design and operations of spacecraft by non-traditional space companies. The evolution in the space sector, precipitated by new players, is often referred to as “Space 4.0” or “New Space”. It necessitates a rethinking of the way satellites and satellite constellations are planned, designed, and operated. New operational paradigms are needed to enable automatic, optimal task definition, and scheduling in a holistic approach.This is the second of two companion papers that investigate the operations of distributed satellite systems. This second article investigates the classification of distributed satellite systems and evaluates commercial tools for automated spacecraft operations, whereas the first article performed a survey of conventional and “new space”operations of spacecraft constellations.Classification metrics for constellations are derived and evaluated with respect to their informative value concerning the operation, the automation, and the scalability of the constellation. The proposed classification system is applied to the Dove and RapidEye constellation and allows for a comparison between the presented automation approaches. Commercial tools for automated spacecraft operations are evaluated for several mission task elements, such as orbit control, orbit maintenance, and collision avoidance. Subsequently, the trends, benefits, and standardization needs for operational automation are identified.