SHERPA: A Flexible, Modular Spacecraft for Orbit Transfer and On-Orbit Operations

The Department of Defense Space Test Program is responsible for launching small experimental payloads and demonstration technologies as directed by the Space Experiments Review Board (SERB). The Shuttle Expendable Rocket for Payload Augmentation (SHERPA) program will develop a highly functional space vehicle – with several variants – that incorporates a scaleable, modular architecture to support a wide variety of missions, technologies, and configurations. The initial application of SHERPA will be as an orbit transfer vehicle designed to raise a payload from a low Space Transportation System (STS) flight altitude to an orbit with a nominal one-year lifetime. This capability will allow STP to take advantage of the low-cost Space Shuttle launch services and still achieve the mission lifetimes required for experiments. In this paper, analysis and design of the SHERPA scalable, modular architecture will be discussed. In addition, applicable requirements and constraints levied upon the design by the customer, secondary payload deployment mechanisms, such as the Canister for All Payload Ejections (CAPE), STS safety, the concept of operations, and envisioned applications, will be addressed

Development of a Light-Weight, Reliable, Booster System for SHELS-Launched Payloads

Small satellite missions are often used to support low-cost space missions demonstrating new technologies. An economical source of low-cost space lift is to fly these satellites as secondary payloads aboard the Space Shuttle. The Shuttle has accommodations for flying these payloads using the Shuttle Hitchhiker Experiment Launch System (SHELS). While the relative costs for a Shuttle launch are at least an order of magnitude below the cost of a dedicated Expendable Launch Vehicle (ELV), final orbit altitude selection is limited to Shuttle mission goals. The Air Force Space Test Program (STP) is responsible for flying the Space Experiments Review Board (SERB) recommended experiments on a level-of-effort basis. Low-cost space lift is crucial to maximizing the number of SERB payloads that STP can support. Unfortunately, the typical Shuttle orbit does not provide a high enough orbit to guarantee the oneyear orbital lifetime required to meet STP mission objectives. A low-cost, autonomous STP Transfer Upper stage, Guided (TUG) that can boost an STP payload from a typical Shuttle orbit to a higher, longer duration orbit would allow STP to take advantage of the low-cost space lift provided by the Shuttle and still meet their mission requirements. The Air Force Research Laboratory Space Vehicles Directorate (AFRL/VS) is pursuing a solution to fulfill STP’s satellite lifting requirements by developing a low-cost, lightweight, reliable, strap-on propulsion module using several Small Business Innovative Research (SBIR) contracts focused on various parts of the TUG system. The Shuttle Expendable Rocket for Payload Augmentation (SHERPA) program will integrate all of these SBIR programs to meet the STP TUG requirement. The TUG system would be composed of several technologies being developed or already developed by AFRL/VS such as separation systems, guidance systems, propulsion modules, and modular bus architecture. The TUG would be re-startable for multiple orbit changes, station keeping, or deorbiting at the completion of a mission. Three versions of the TUG are envisioned. The first is a simple propulsion module that uses the satellite\u27s Attitude Control System (ACS) and Guidance, Navigation, and Control (GN&C) to provide stack guidance. The second is a fully autonomous TUG that lifts the payload to the higher orbit as cargo, separates from the payload, and then accomplishes a collision avoidance maneuver and propellant burn after payload separation. The third configuration is an autonomous TUG with a long duration module that allow experiments to use the TUG\u27s ACS, GN&C, and power systems in the intended final orbit. There are many challenges in the development of this vehicle. The most difficult of these is meeting the man-rating requirements of the Shuttle. All critical systems must have triple redundancy to ensure that the system does not threaten the Shuttle, its crew, or its mission. Another complication is producing a structure that meets the strict mass and volume restrictions of the SHELS system. Integration is als o a challenge, as many contractors and technologies are brought together under this program

Demonstration of a New Smallsat Launch Vehicle: The Orbital/Suborbital Program (OSP) Space Launch Vehicle Inaugural Mission Results

The United States Air Force and Orbital Sciences Corporation (Orbital) completed development and demonstration of a new low cost space launch vehicle for launching small satellites using surplus Minuteman II rocket motors melded with commercial launch vehicle technology. The Orbital Suborbital Program Space Launch Vehicle (OSPSLV, aka OSP Minotaur) successfully achieved all mission objectives with the inaugural launch into a 405 nm circular, 100 deg inclination orbit on 26 January, 2000. This launch achieved “firsts” in several areas including being the first space launch utilizing Minuteman boosters. It was also the first launch from the California Spaceport (Spaceport Systems International Commercial Launch Facility) at Vandenberg AFB. The OSP Minotaur accurately delivered a total of 11 satellites to orbit on its inaugural launch, involving complex maneuvering and multiple payload separations. Satellite sizes covered the range from minisatellite (JAWSAT Multiple Payload Adapter (MPA), 110 kg), microsatellite (USAFA’s FalconSat, 50 kg, and OPAL, 20kg), nanosatellite (Arizona State University’s ASUSat-1.5 kg), and picosatellites (ARPA/Aerospace, ARTEMIS, STENSAT, and MASAT, 0.5 kg each). ASUSat-1 was the first scientific nanosatellite and the picosats were the world’s first active “pico” satellites. Additionally, an Optical Calibration Sphere was placed into orbit for the Air Force Research Laboratory (AFRL) Starfire Optical Range. The mission also demonstrated the Soft Ride for Small Satellites (SRSS) full-spacecraft isolation system developed by AFRL and CSA Engineering. The OSP Minotaur is a four stage, ground launched solid propellant inertially guided spacelift vehicle. It is capable of putting up to 1400 lbm into LEO (100 nm, 28.5 deg) and over 700 lbm into a 400 nm, sunsynchronous orbit. The first two stages are from surplus Minuteman II ICBM’s (M-55 and SR-19). They are combined with the upper two stages (Orion 50XL and Orion 38), structure, and fairing from Orbital’s Pegasus XL air-launched space vehicle. However, new flight software, avionics, and telemetry components provide greater payload support capability relative to the Pegasus system

CASPAR Low-Cost, Dual-Manifest Payload Adapter for Minotaur IV

The Minotaur IV Launch Vehicle is being developed by the Air Force Rocket Systems Launch Program (RSLP) to utilize excess Peacekeeper missile motors and provide low-cost launches for Government payloads to Low Earth Orbit (LEO). This vehicle uses three Peacekeeper stages, an Orion 38 motor, and avionics from the heritage Minotaur I vehicle. Nominal capability for Minotaur IV is almost 4000 lbm to LEO. The fly-away cost is just over $20 million. The Composite Adapter for Shared PAyload Rides (CASPAR) Multi-Payload Adapter (MPA) will enable a Minotaur IV to launch two large satellites (1000-2000 lbm) for about$10 million each. The CASPAR MPA is being designed for projected Minotaur IV launch load environments, with design objectives of light weight, integrated vibration isolation, low shock, and modularity. An innovative composite design, including co-cured composite stiffening, provides a lightweight structure with optional access doors. Low-shock separation systems are integrated for MPA and satellite separation events. Vibration isolation systems protect the payloads from the dynamic environment of the Peacekeeper motor stack, and isolation tuning will enable a range of payloads and facilitate modular designs. Qualification testing of a full-scale adapter is planned for early 2006. Design variations are being considered for existing and new launch vehicles

Spin and Chirality Effects in Antler-Topology Processes at High Energy e+e−e^+e^- Colliders

We perform a model-independent investigation of spin and chirality correlation effects in the antler-topology processes $e^+e^-\to\mathcal{P}^+\mathcal{P}^-\to (\ell^+ \mathcal{D}^0) (\ell^-\mathcal{\bar{D}}^0)$ at high energy $e^+e^-$ colliders with polarized beams. Generally the production process $e^+e^-\to\mathcal{P}^+\mathcal{P}^-$ can occur not only through the $s$-channel exchange of vector bosons, $\mathcal{V}^0$, including the neutral Standard Model (SM) gauge bosons, $\gamma$ and $Z$, but also through the $s$- and $t$-channel exchanges of new neutral states, $\mathcal{S}^0$ and $\mathcal{T}^0$, and the $u$-channel exchange of new doubly-charged states, $\mathcal{U}^{--}$. The general set of (non-chiral) three-point couplings of the new particles and leptons allowed in a renormalizable quantum field theory is considered. The general spin and chirality analysis is based on the threshold behavior of the excitation curves for $\mathcal{P}^+\mathcal{P}^-$ pair production in $e^+e^-$ collisions with longitudinal and transverse polarized beams, the angular distributions in the production process and also the production-decay angular correlations. In the first step, we present the observables in the helicity formalism. Subsequently, we show how a set of observables can be designed for determining the spins and chiral structures of the new particles without any model assumptions. Finally, taking into account a typical set of approximately chiral invariant scenarios, we demonstrate how the spin and chirality effects can be probed experimentally at a high energy $e^+e^-$ collider.Comment: 50 pages, 14 figures, 6 tables, matches version published in EPJ

A retrospective and agenda for future research on Chinese outward foreign direct investment

Our original paper “The determinants of Chinese Outward Foreign Direct Investment” was the first theoretically based empirical analysis of the phenomenon. It utilised internalisation theory to show that Chinese state-owned firms reacted to home country market imperfections to surmount barriers to foreign entry arising from naivety and the lack of obvious ownership advantages, leveraging institutional factors including favourable policy stimuli. This special theory explained outward foreign direct investment (OFDI) but provided surprises. These included the apparent appetite for risk evinced by these early investors, causing us to conjecture that domestic market imperfections, particularly in the domestic capital market, might be responsible. The article stimulated a massive subsequent, largely successful, research effort on emerging country multinationals. In this Retrospective article we review some of the main strands of research that ensued, for the insight they offer for the theme of our commentary. Our theme is that theoretical development can only come through embracing yet more challenging, different, and new contexts, and we make suggestions for future research directions

Can Hearts and Minds be Bought? The Economics of Counterinsurgency in

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. We develop and test an economic theory of insurgency motivated by the informal literature and by recent military doctrine. We model a three-way contest between violent rebels, a government seeking to minimize violence by mixing service provision and coercion, and ciWe acknowledge the comments of seminar participants at the Western Economic Association, the National The University of Chicago Pres

Parallel molecular routes to cold adaptation in eight genera of New Zealand stick insects.

The acquisition of physiological strategies to tolerate novel thermal conditions allows organisms to exploit new environments. As a result, thermal tolerance is a key determinant of the global distribution of biodiversity, yet the constraints on its evolution are not well understood. Here we investigate parallel evolution of cold tolerance in New Zealand stick insects, an endemic radiation containing three montane-occurring species. Using a phylogeny constructed from 274 orthologous genes, we show that stick insects have independently colonized montane environments at least twice. We compare supercooling point and survival of internal ice formation among ten species from eight genera, and identify both freeze tolerance and freeze avoidance in separate montane lineages. Freeze tolerance is also verified in both lowland and montane populations of a single, geographically widespread, species. Transcriptome sequencing following cold shock identifies a set of structural cuticular genes that are both differentially regulated and under positive sequence selection in each species. However, while cuticular proteins in general are associated with cold shock across the phylogeny, the specific genes at play differ among species. Thus, while processes related to cuticular structure are consistently associated with adaptation for cold, this may not be the consequence of shared ancestral genetic constraints

Study of the reaction e^{+}e^{-} -->J/psi\pi^{+}\pi^{-} via initial-state radiation at BaBar

We study the process $e^+e^-\to J/\psi\pi^{+}\pi^{-}$ with initial-state-radiation events produced at the PEP-II asymmetric-energy collider. The data were recorded with the BaBar detector at center-of-mass energies 10.58 and 10.54 GeV, and correspond to an integrated luminosity of 454 $\mathrm{fb^{-1}}$. We investigate the $J/\psi \pi^{+}\pi^{-}$ mass distribution in the region from 3.5 to 5.5 $\mathrm{GeV/c^{2}}$. Below 3.7 $\mathrm{GeV/c^{2}}$ the $\psi(2S)$ signal dominates, and above 4 $\mathrm{GeV/c^{2}}$ there is a significant peak due to the Y(4260). A fit to the data in the range 3.74 -- 5.50 $\mathrm{GeV/c^{2}}$ yields a mass value $4244 \pm 5$ (stat) $\pm 4$ (syst)$\mathrm{MeV/c^{2}}$ and a width value $114 ^{+16}_{-15}$ (stat)$\pm 7$(syst)$\mathrm{MeV}$ for this state. We do not confirm the report from the Belle collaboration of a broad structure at 4.01 $\mathrm{GeV/c^{2}}$. In addition, we investigate the $\pi^{+}\pi^{-}$ system which results from Y(4260) decay

Simultaneous Impact of the Presence of Foreign MNEs on Indigenous Firms’ Exports and Domestic Sales

YesIncorporating the global production network approach and competitor analysis, this paper establishes an analytical framework with two hypotheses for the role of foreign multinational enterprises (FMNEs) in indigenous firms’ exports and domestic sales. First, the presence of FMNEs as a whole is likely to have a negative impact on indigenous firms’ domestic sales but a simultaneous positive impact on their exports in an emerging economy like China. Second, the presence of MNEs from Hong Kong, Macau and Taiwan (HMT MNEs) is more likely to generate this pattern of impact than MNEs from other countries (Other FMNEs). The FDI-led export strategy contributed to the dominance of the scenario described by the first hypothesis in China, while a higher degree of market commonality and resource similarity of HMT MNEs with that of indigenous Chinese firms than Other FMNEs leads to the second hypothesis. These novel hypotheses are tested and supported by a very large and recent firm-level panel dataset from Chinese manufacturing