The aerodynamic challenges of SRB recovery

Recovery and reuse of the Space Shuttle solid rocket boosters was baselined to support the primary goal to develop a low cost space transportation system. The recovery system required for the 170,000-lb boosters was for the largest and heaviest object yet to be retrieved from exoatmospheric conditions. State-of-the-art design procedures were ground-ruled and development testing minimized to produce both a reliable and cost effective system. The ability to utilize the inherent drag of the boosters during the initial phase of reentry was a key factor in minimizing the parachute loads, size and weight. A wind tunnel test program was devised to enable the accurate prediction of booster aerodynamic characteristics. Concurrently, wind tunnel, rocket sled and air drop tests were performed to develop and verify the performance of the parachute decelerator subsystem. Aerodynamic problems encountered during the overall recovery system development and the respective solutions are emphasized

Mars Lander Vehicle/Parachute Dynamics

Parachute decelerators used exclusively or in combination with retro rockets have been considered prime candidates for the terminal descent and landing system of a scientifically instrumented Mars lander. The objective of this study is to understand basic relationships between parameters affecting dynamic response of the parachute and capsule and to define those aspects of the system which have a sensitive effect on the design of the lander capsule. Of particular interest is the response of the capsule to wind gusts and to establish the sensitivity to gust onset rates in the VM series of Martian atmospheres. The model used in studying parachute/capsule relationships consists of two bodies, each with three degrees-of-freedom, connected by an elastic riser cable. The total elastic nature of the parachute and shroud lines is simulated by the equivalent elasticity of the riser cable. The parachute and its enclosed and apparent inertia effects are treated in a rigid body sense. Parachute opening phase dynamics are included in the analysis model. Motion of the system is examined in either the pitch or yaw plane with roll motion assumed to be controlled near zero by an attitude control system. Capsule attitude excursions and attitude rates are investigated in detail because of their impact on optical and radar sensors. The ability of a simple rate damping attitude control system to combat capsule oscillations is included in the study. Usually a planetary entry vehicle utilizes a blunt body aeroshell coated with ablative material for the high dynamic pressure, high Mach number portion of the entry trajectory. Once this region has been traversed and Mach number is reduced to approximately 1.6, the parachute decelerator may be deployed. From this point on, the aeroshell serves little usefulness and may complicate the touchdown mechanics. It may be desirable, therefore to jettison the aeroshell as soon as possible after parachute deployment. The ease of accomplishing aeroshell separation while descending on a parachute is evaluated

Balloon launched Viking decelerator test program

Four BLDT flights were conducted during the summer of 1972. The purpose of these tests was to qualify the Viking parachute system behind the full-scale Viking entry vehicle over the maximum range of entry conditions anticipated in the Viking '75 soft landing on Mars. A summary of the test series is presented. Test conditions ranged from a Mach number of 2.0 to 0.5 and dynamic pressure from 11.7 to 4.4 psf. This range of conditions covers the uncertainty in entry conditions at Mars due to atmospheric and entry performance uncertainties. Emphasis is placed on parachute performance and simulated Mars entry vehicle motions as influenced by the parachute performance. Conclusions are presented regarding the ability of the parachute to perform within the operational parameters required for a successful soft Martian landing. A list of references which covers all reports in the qualification test program is included

Video guidance, landing, and imaging systems

The adaptive potential of video guidance technology for earth orbital and interplanetary missions was explored. The application of video acquisition, pointing, tracking, and navigation technology was considered to three primary missions: planetary landing, earth resources satellite, and spacecraft rendezvous and docking. It was found that an imaging system can be mechanized to provide a spacecraft or satellite with a considerable amount of adaptability with respect to its environment. It also provides a level of autonomy essential to many future missions and enhances their data gathering ability. The feasibility of an autonomous video guidance system capable of observing a planetary surface during terminal descent and selecting the most acceptable landing site was successfully demonstrated in the laboratory. The techniques developed for acquisition, pointing, and tracking show promise for recognizing and tracking coastlines, rivers, and other constituents of interest. Routines were written and checked for rendezvous, docking, and station-keeping functions

High frequency of chlamydial co-infections in clinically healthy sheep flocks

<p>Abstract</p> <p>Background</p> <p>The epidemiological situation of ovine chlamydial infections in continental Europe, especially Germany is poorly characterised. Using the German state of Thuringia as a model example, the chlamydial sero- and antigen prevalence was estimated in thirty-two randomly selected sheep flocks with an average abortion rate lower than 1%. Seven vaccinated flocks were reviewed separately.</p> <p>Results</p> <p>A wide range of samples from 32 flocks were examined. Assumption of a seroprevalence of 10% (CI 95%) at flock level, revealed that 94% of the tested flocks were serologically positive with ongoing infection (i.e. animals with seroconversion) in nearly half (47%) of the flocks. On the basis of an estimated 25% antigen prevalence (CI 95%), PCR and DNA microarray testing, together with sequencing revealed the presence of chlamydiae in 78% of the flocks. The species most frequently found was <it>Chlamydophila (C</it>.) <it>abortus </it>(50%) followed by <it>C. pecorum </it>(47%) and <it>C. psittaci </it>genotype A (25%). Mixed infections occurred in 25% of the tested flocks. Samples obtained from the vaccinated flocks revealed the presence of <it>C. abortus </it>field samples in 4/7 flocks. <it>C. pecorum </it>was isolated from 2/7 flocks and the presence of seroconversion was determined in 3/7 flocks.</p> <p>Conclusions</p> <p>The results imply that chlamydial infections occur frequently in German sheep flocks, even in the absence of elevated abortion rates. The fact that <it>C. pecorum </it>and the potentially zoonotic <it>C. psittaci </it>were found alongside the classical abortifacient agent <it>C. abortus</it>, raise questions about the significance of this reservoir for animal and human health and underline the necessity for regular monitoring. Further studies are needed to identify the possible role of <it>C. psittaci </it>infections in sheep.</p

Correspondence between hair cortisol concentrations and 30-day integrated daily salivary and weekly urinary cortisol measures

Characterization of cortisol production, regulation and function is of considerable interest and relevance given its ubiquitous role in virtually all aspects of physiology, health and disease risk. The quantification of cortisol concentration in hair has been proposed as a promising approach for the retrospective assessment of integrated, long-term cortisol production. However, human research is still needed to directly test and validate current assumptions about which aspects of cortisol production and regulation are reflected in hair cortisol concentrations (HCC). Here, we report findings from a validation study in a sample of 17 healthy adults (mean ± SD age: 34 ± 8.6 yrs). To determine the extent to which HCC captures cumulative cortisol production, we examined the correspondence of HCC, obtained from the first 1cm scalp-near hair segment, assumed to retrospectively reflect 1-month integrated cortisol secretion, with 30-day average salivary cortisol area-under-the curve (AUC) based on 3 samples collected per day (on awakening, +30 min, at bedtime) and the average of 4 weekly 24-hr urinary free cortisol (UFC) assessments. To further address which aspects of cortisol production and regulation are best reflected in the HCC measure, we also examined components of the salivary measures that represent: 1) production in response to the challenge of awakening (using the cortisol awakening response [CAR]), and 2) chronobiological regulation of cortisol production (using diurnal slope). Finally, we evaluated the test-retest stability of each cortisol measure. Results indicate that HCC was most strongly associated with the prior 30-day integrated cortisol production measure (average salivary cortisol AUC) (r = 0.61, p = 0.01). There were no significant associations between HCC and the 30-day summary measures using CAR or diurnal slope. The relationship between 1-month integrated 24-hr UFC and HCC did not reach statistical significance (r = 0.30, p = 0.28). Lastly, of all cortisol measures, test-retest correlations of serial measures were highest for HCC (month-to-month: r = 0.84, p < 0.001), followed by 24-hr UFC (week-to-week: r’s between 0.59 and 0.68, ps < 0.05) and then integrated salivary cortisol concentrations (week-to-week: r’s between 0.38 and 0.61, p’s between 0.13 and 0.01). These findings support the contention that HCC provides a reliable estimate of long-term integrated free cortisol production that is aligned with integrated salivary cortisol production measured over a corresponding one-month period

Inorganic Nanoparticles for Biomedical Applications

Polymer, lipid, metal, semiconductor, and hybrid composite nanoparticles with dimensions < 100 nm, have been developed extensively for potential biomedical applications like drug delivery systems, molecular sensing devices, and diagnostic imaging. In this overview, only inorganic nanoparticles for drug delivery will be addressed. Inorganic nanoparticles exhibit magnetic, electrical and optical properties that differed from their bulk counterparts. These physical properties could be tailored by controlling the size, shape, surface, and domain interactions in the nanoparticles. The incorporation of the unique properties of nanoparticles has expanded alternative platforms for drug delivery. The drug delivery systems highlighted in this overview include unguided, magnetically-guided, and optically-triggered delivery systems. These delivery systems are developed to enable improved localization and control of the drug’s sphere of influence. This would potentially allow for more efficient therapy with lower dosages and reduced adverse side effects

Space Shuttle Solid Rocket Booster Lightweight Recovery System

The cancellation of the Advanced Solid Rocket Booster Project and the earth-to-orbit payload requirements for the Space Station dictated that the National Aeronautics and Space Administration (NASA) look at performance enhancements from all Space Transportation System (STS) elements (Orbiter Project, Space Shuttle Main Engine Project, External Tank Project, Solid Rocket Motor Project, & Solid Rocket Booster Project). The manifest for launching of Space Station components indicated that an additional 12-13000 pound lift capability was required on 10 missions and 15-20,000 pound additional lift capability is required on two missions. Trade studies conducted by all STS elements indicate that by deleting the parachute Recovery System (and associated hardware) from the Solid Rocket Boosters (SRBS) and going to a lightweight External Tank (ET) the 20,000 pound additional lift capability can be realized for the two missions. The deletion of the parachute Recovery System means the loss of four SRBs and this option is two expensive (loss of reusable hardware) to be used on the other 10 Space Station missions. Accordingly, each STS element looked at potential methods of weight savings, increased performance, etc. As the SRB and ET projects are non-propulsive (i.e. does not have launch thrust elements) their only contribution to overall payload enhancement can be achieved by the saving of weight while maintaining adequate safety factors and margins. The enhancement factor for the SRB project is 1:10. That is for each 10 pounds saved on the two SRBS; approximately 1 additional pound of payload in the orbiter bay can be placed into orbit. The SRB project decided early that the SRB recovery system was a prime candidate for weight reduction as it was designed in the early 1970s and weight optimization had never been a primary criteria