The ROCSAT-1 Spacecraft

TRW is under contract to the Republic of China\u27s (ROC) National Space Program Office (NSPO) to build the spacecraft for ROCSAT-1, the first satellite in the ROC\u27s civilian space program. The ROCSAT-1 spacecraft is the next generation of TRW\u27s Eagle-class lightsats which were developed for the USAF\u27s Space Test Experiment Platform (STEP) program and upgraded for NASA\u27s Total Ozone Mapping Spectrometer (TOMS) program. The spacecraft will be developed in Redondo Beach, CA by a team of ROC and US engineers and delivered to Hsin-chu, Taiwan, ROC for integration with three experiments supplied by the NSPO: a space physics experiment, an ocean color imager and a Ka-band telecommunications relay experiment. The ~ 400 Kg satellite will be launched on a small satellite launch vehicle into circular 600 km altitude, 35 degree inclination orbit in late 1997. This paper briefly describes the mission, spacecraft and subsystem designs

A3_7 Density of an Elf

In the film and book ‘The Fellowship of the Ring,’ the elf Legolas is shown to walk on the surface of a snow bank. This paper outlines the investigation into the density the character, as portrayed by Orlando Bloom, would have to be in order for this to be a possibility. It was found that his mass would be 6.05×10−5 kg, giving him a density of 7.75×10−4 kgm-3

A3_3 When the Preacher shot the Priest

In Preacher, Jesse Custer shoots Allfather in the chest with a pistol, knocking him to the ground. The Allfather then stands up and pulls the bullet out of the body fat of his chest with a pair of chopsticks, his body fat having absorbed the force from the bullet and kept him alive. In this paper we find out if this feat is possible by finding the depth of human body fat required to stop a bullet fired from a pistol six metres from the target. This distance - considering reductions in velocity from air resistance and piercing human skin - was found to be s = 21.17m

A 4-m evolvable space telescope configured for NASA's HabEx Mission: the initial stage of LUVOIR

Previous papers have described our concept for a large telescope that would be assembled in space in several stages (in different configurations) over a period of fifteen to 20 years. Spreading the telescope development, launch and operations cost over 20 years would minimize the impact on NASA’s annual budget and drastically shorten the time between program start and “first light” for this space observatory. The first Stage of this Evolvable Space Telescope (EST) would consist of an instrument module located at the prime focus of three 4-meter hexagonal mirrors arranged in a semi-circle to form one-half of a 12-m segmented mirror. After several years three additional 4-m mirrors would be added to create a 12-m filled aperture. Later, twelve more 4-m mirrors will be added to this Stage 2 telescope to create a 20-m filled aperture space telescope. At each stage the telescope would have an unparalleled capability for UVOIR observations, and the results of these observations will guide the evolution of the telescope and its instruments. In this paper we describe our design concept for an initial configuration of our Evolvable Space Telescope that can meet the requirements of the 4-m version of the HabEx spacecraft currently under consideration by NASA’s Habitable Exoplanet Science and Technology Definition Team. This “Stage Zero” configuration will have only one 4-m mirror segment with the same 30-m focal length and a prime focus coronagraph with normal incidence optics to minimize polarization effects. After assembly and checkout in cis-lunar space, the telescope would transfer to a Sun-Earth L2 halo orbit and obtain high sensitivity, high resolution, high contrast UVOIR observations that address the scientific objectives of the Habitable-Exoplanet Imaging Missions

A new paradigm for space astrophysics mission design

Pursuing ground breaking science in a highly cost-constrained environment presents new challenges to the development of future space astrophysics missions. Within the conventional cost models for large observatories, executing a flagship “mission after next” appears to be unstainable. To achieve our nation’s science ambitions requires a new paradigm of system design, development and manufacture. This paper explores the nature of the current paradigm and proposes a series of steps to guide the entire community to a sustainable future

An evolvable space telescope for future astronomical missions

Astronomical flagship missions after JWST will require affordable space telescopes and science instruments. Innovative spacecraft-electro-opto-mechanical system architectures matched to the science requirements are needed for observations for exoplanet characterization, cosmology, dark energy, galactic evolution formation of stars and planets, and many other research areas. The needs and requirements to perform this science will continue to drive us toward larger and larger apertures. Recent technology developments in precision station keeping of spacecraft, interplanetary transfer orbits, wavefront/sensing and control, laser engineering, macroscopic application of nano-technology, lossless optical designs, deployed structures, thermal management, interferometry, detectors and signal processing enable innovative telescope/system architectures with break-through performance. Unfortunately, NASA’s budget for Astrophysics is unlikely to be able to support the funding required for the 8 m to 16 m telescopes that have been studied as a follow-on to JWST using similar development/assembly approaches without decimating the rest of the Astrophysics Division’s budget. Consequently, we have been examining the feasibility of developing an “Evolvable Space Telescope” that would begin as a 3 to 4 m telescope when placed on orbit and then periodically be augmented with additional mirror segments, structures, and newer instruments to evolve the telescope and achieve the performance of a 16 m or larger space telescope. This paper reviews the approach for such a mission and identifies and discusses candidate architectures

The precision electroweak data in warped extra-dimension models

The Randall-Sundrum scenario with Standard Model fields in the bulk and a custodial symmetry is considered. We determine the several minimal quark representations allowing to address the anomalies in the forward-backward b-quark asymmetry A^b_FB, while reproducing the bottom and top masses via wave function overlaps. The calculated corrections of the Zbb coupling include the combined effects of mixings with both Kaluza-Klein excitations of gauge bosons and new b'-like states. It is shown that the mechanism, in which the left-handed doublet of third generation quarks results from a mixing on the UV boundary of introduced fields Q_1L and Q_2L, is necessary for phenomenological reasons. Within the obtained models, both the global fit of R_b with A^b_FB [at the various center of mass energies] and the fit of last precision electroweak data in the light fermion sector can simultaneously be improved significantly with respect to the pure Standard Model case, for M_KK = 3,4,5 TeV (first KK gauge boson) and a best-fit Higgs mass m_h > 115 GeV i.e. compatible with the LEP2 direct limit. The quantitative analysis of the oblique parameters S,T,U even shows that heavy Higgs mass values up to ~500 GeV may still give rise to an acceptable quality of the electroweak data fit, in contrast with the Standard Model. The set of obtained constraints on the parameter space, derived partly from precision electroweak data, is complementary of a future direct exploration of this parameter space at the LHC. In particular, we find that custodians, like b' modes, can be as light as ~1200 GeV i.e. a mass lying possibly in the potential reach of LHC.Comment: 24 pages, 8 figures. Added references, corrected typos and Higgs mass dependence discussion complete

New Worlds Observer Optical Performance

ABSTRACT New Worlds Observer is an external occulter, or, starshade, mission designed to detect visible wavelength (less than 1 micron) light from Earth-like planets around solar neighborhood stars. A telescope spacecraft operates in the "shadow" cast by a starshade spacecraft, located tens of thousands of kilometers away. The specially contoured petals on the starshade spacecraft control the diffraction to produce high contrast suppression of the on-axis starlight. The starshade operates in the Fresnel, or near field, diffraction regime, which adds complexity to numerical simulations of its performance. As a validation of the numerical models and a demonstration of the starshade capabilities, we have built a testbed to measure the performance of subscale NWO hypergaussian starshades. We describe the rationale for our testbed and its set up. We expect to be able to report results from the testbed in a later paper this year

An evolvable space telescope for future astronomical missions 2015 update

In 2014 we presented a concept for an Evolvable Space Telescope (EST) that was assembled on orbit in 3 stages, growing from a 4x12 meter telescope in Stage 1, to a 12-meter filled aperture in Stage 2, and then to a 20-meter filled aperture in Stage 3. Stage 1 is launched as a fully functional telescope and begins gathering science data immediately after checkout on orbit. This observatory is then periodically augmented in space with additional mirror segments, structures, and newer instruments to evolve the telescope over the years to a 20-meter space telescope. In this 2015 update of EST we focus upon three items: 1) a restructured Stage 1 EST with three mirror segments forming an off-axis telescope (half a 12-meter filled aperture); 2) more details on the value and architecture of the prime focus instrument accommodation; and 3) a more in depth discussion of the essential in-space infrastructure, early ground testing and a concept for an International Space Station testbed called MoDEST. In addition to the EST discussions we introduce a different alternative telescope architecture: a Rotating Synthetic Aperture (RSA). This is a rectangular primary mirror that can be rotated to fill the UV-plane. The original concept was developed by Raytheon Space and Airborne Systems for non-astronomical applications. In collaboration with Raytheon we have begun to explore the RSA approach as an astronomical space telescope and have initiated studies of science and cost performance

Topological pupil segmentation and point spread function analysis for large aperture imaging systems

Future large aperture telescopes and high contrast imaging systems will often include segment gaps, structural obscurations, along with outer edges which produce diffraction effects that are disadvantageous to high contrast imaging (e.g., for exoplanet detection) or continuous wavefront control across the optical aperture. We present an optimization strategy for several pupil segment topologies for next-generation telescope concepts. Wave propagation results based on diffraction-limited point spread function analyses using Fraunhofer diffraction theory are presented using the Python-based POPPY simulation tool