High-Payoff Space Transportation Design Approach with a Technology Integration Strategy

A general architectural design sequence is described to create a highly efficient, operable, and supportable design that achieves an affordable, repeatable, and sustainable transportation function. The paper covers the following aspects of this approach in more detail: (1) vehicle architectural concept considerations (including important strategies for greater reusability); (2) vehicle element propulsion system packaging considerations; (3) vehicle element functional definition; (4) external ground servicing and access considerations; and, (5) simplified guidance, navigation, flight control and avionics communications considerations. Additionally, a technology integration strategy is forwarded that includes: (a) ground and flight test prior to production commitments; (b) parallel stage propellant storage, such as concentric-nested tanks; (c) high thrust, LOX-rich, LOX-cooled first stage earth-to-orbit main engine; (d) non-toxic, day-of-launch-loaded propellants for upper stages and in-space propulsion; (e) electric propulsion and aero stage control

A luminescent gold complex: bis-μ-[bis(dicyclohexylphosphino)ethane-P,P']-digold bis(hexafluorophosphate)

[Au_2(C_(26)H_(48)P_2h](PF_6)_2, M_r = 1529·1, tetragonal, P4n2, ɑ= 15·917 (5), c = 12-448 (1) A, V = 3154 (1) A3 , Z = 2, Dx = 1·61 g cm^(-3), λ(Mo Ka) = 0·71073 A, μ = 50·1 cm^(-1), F(000) = 1528, room temperature (297 K), R = 0·064 for 3525 reflections with F/_o^2 > 0,0·038 for 2440 with F/_o^2 > 3σ(F/_o^2). This [Au_2(C_26)H_(48)P_2)_2] (PF_6)_2 compound shows a strong luminescence in the solid state at 77 K. The cation consists of two Au atoms joined by two bis (dicyclohexylphosphino )ethane links, with one Au atom and one half of a link being the asymmetric unit. The Au-Au distance [2·936 (1) Å] is only slightly longer than the 2·884 Å found in gold metal, indicative of substantial metal-metal bonding

Three-body decay of 6^{6}Be

Three-body correlations for the ground-state decay of the lightest two-proton emitter $^{6}$Be are studied both theoretically and experimentally. Theoretical studies are performed in a three-body hyperspherical-harmonics cluster model. In the experimental studies, the ground state of $^{6}$Be was formed following the $\alpha$ decay of a $^{10}$C beam inelastically excited through interactions with Be and C targets. Excellent agreement between theory and experiment is obtained demonstrating the existence of complicated correlation patterns which can elucidate the structure of $^{6}$Be and, possibly, of the A=6 isobar.Comment: 17 pages, 21 figures, 5 table

Astrophysical S factor for the radiative capture 12N(p,gamma)13O determined from the 14N(12N,13O)13C proton transfer reaction

The cross section of the radiative proton capture reaction on the drip line nucleus 12N was investigated using the Asymptotic Normalization Coefficient (ANC) method. We have used the 14N(12N,13O)13C proton transfer reaction at 12 MeV/nucleon to extract the ANC for 13O -> 12N + p and calculate from it the direct component of the astrophysical S factor of the 12N(p,gamma)13O reaction. The optical potentials used and the DWBA analysis of the proton transfer reaction are discussed. For the entrance channel, the optical potential was inferred from an elastic scattering measurement carried out at the same time with the transfer measurement. From the transfer, we determined the square of the ANC, C^2(13Og.s.) = 2.53 +/- 0.30 fm-1, and hence a value of 0.33(4) keVb was obtained for the direct astrophysical S factor at zero energy. Constructive interference at low energies between the direct and resonant captures leads to an enhancement of Stotal(0) = 0.42(5) keVb. The 12N(p,gamma)13O reaction was investigated in relation to the evolution of hydrogen-rich massive Population III stars, for the role that it may play in the hot pp-chain nuclear burning processes, possibly occurring in such objects.Comment: 15 pages, 10 figures, 3 tables submitted to Phys. Rev.

An Affordability Comparison Tool (ACT) for Space Transportation

NASA bas recently emphasized the importance of affordability for Commercial Crew Development Program (CCDP), Space Launch Systems (SLS) and Multi-Purpose Crew Vehicle (MPCV). System architects and designers are challenged to come up with architectures and designs that do not bust the budget. This paper describes the Affordability Comparison Tool (ACT) analyzes different systems or architecture configurations for affordability that allows for a comparison of: total life cycle cost; annual recurring costs, affordability figures-of-merit, such as cost per pound, cost per seat, and cost per flight, as well as productivity measures, such as payload throughput. Although ACT is not a deterministic model, the paper develops algorithms and parametric factors that use characteristics of the architectures or systems being compared to produce important system outcomes (figures-of-merit). Example applications of outcome figures-of-merit are also documented to provide the designer with information on the relative affordability and productivity of different space transportation applications

A luminescent gold complex: bis-μ-[bis(dicyclohexylphosphino)ethane-P,P']-digold bis(hexafluorophosphate)

[Au_2(C_(26)H_(48)P_2h](PF_6)_2, M_r = 1529·1, tetragonal, P4n2, ɑ= 15·917 (5), c = 12-448 (1) A, V = 3154 (1) A3 , Z = 2, Dx = 1·61 g cm^(-3), λ(Mo Ka) = 0·71073 A, μ = 50·1 cm^(-1), F(000) = 1528, room temperature (297 K), R = 0·064 for 3525 reflections with F/_o^2 > 0,0·038 for 2440 with F/_o^2 > 3σ(F/_o^2). This [Au_2(C_26)H_(48)P_2)_2] (PF_6)_2 compound shows a strong luminescence in the solid state at 77 K. The cation consists of two Au atoms joined by two bis (dicyclohexylphosphino )ethane links, with one Au atom and one half of a link being the asymmetric unit. The Au-Au distance [2·936 (1) Å] is only slightly longer than the 2·884 Å found in gold metal, indicative of substantial metal-metal bonding

Beta-delayed proton decay of proton-rich nuclei 23Al and 31Cl and explosive H-burning in classical novae

We have developed a technique to measure beta-delayed proton decay of proton-rich nuclei produced and separated with the MARS recoil spectrometer of Texas A&M University. The short-lived radioactive species are produced in-flight, separated, then slowed down (from about 40 MeV/u) and implanted in the middle of very thin Si detectors. The beam is pulsed and beta-p decay of the pure sources collected in beam is measured between beam pulses. Implantation avoids the problems with detector windows and allows us to measure protons with energies as low as 200 keV from nuclei with lifetimes of 100 ms or less. Using this technique, we have studied the isotopes 23Al and 31Cl, both important for understanding explosive H-burning in novae. They were produced in the reactions 24Mg(p,2n)23Al and 32S(p,2n)31Cl, respectively, in inverse kinematics, from stable beams at 48 and 40 MeV/u, respectively. We give details about the technique, its performances and the results for 23Al and 31Cl beta-p decay. The technique has shown a remarkable selectivity to beta-delayed charged-particle emission and would work even at radioactive beam rates of a few pps. The states populated are resonances for the radiative proton capture reactions 22Na(p,g)23Mg and 30P(p,g)31S, respectively.Comment: Submitted on Oct. 6, 2008 for the Proceedings of the 10th Symposium on Nuclei in the Cosmos Mackinac Island, Michigan, USA 27 July - 1 August, 2008 Acceptance pendin