Payload Bay Research Articles

Orbital maneuvering vehicle: A new capability

The Orbital Maneuvering Vehicle (OMV) is a reusable, remotely controlled, free-flying vehicle being developed by NASA to perform a wide range of on-orbit missions and services in support of orbiting spacecraft. The OMV is capable of satellite delivery, retrieval, reboost, controlled deorbit, viewing, and subsatellite support missions. It is an important extension to the Space Transportation System and a key element of the Space Station operational scenario. The OMV can operate from the Shuttle, the Space Station, or can be space based. The OMV, being 15 ft in diameter and approximately 4 1 2 thick, mounts directly into the Shuttle payload bay. The vehicle design is highly modular, consisting of a Short Range Vehicle containing both hydrazine and cold gas RCS systems and all the avionics systems for electrical power, communications, data management, guidance, navigation, and 6-degree of freedom control. This vehicle weighs approximately 6,500 lb and can accomplish a high percentage of the project missions. For high delta-velocity missions, a bipropellant Propulsion Module (approximately 11,000lb) is added, giving a total weight of 17,500 lb. This module can be exchanged on orbit to effect bipropellant refueling. All the RCS and avionics modules are replaceable on orbit for maintenance. The OMV development program was initiated in 1986 with the selection of TRW as the prime contractor. The first flight is projected for 1991. An early planned use of OMV is to reboost the Hubble Space Telescope when required because of atmospheric drag. This paper contains details of the program status, vehicle description, and mission capabilities. The purpose of the paper is to acquaint the international space community with OMV capabilities and to stimulate the identification of new and unique mission applications.

Plasma parameters in the near wake of the space shuttle

Results are presented from a Spherical Retarding Potential Analyzer (SRPA) and a spherical Langmuir Probe (LP) which were flown on the Spacelab‐2 (SL‐2) mission of the Space Shuttle Orbiter in August, 1985. The probes were mounted in such a position that for certain Orbiter orientations, the wake edge formed by the starboard payload bay sill swept across the probes at a roll rate of once per orbit about an inertially stabilized pointing direction. Profiles of O+ number density and electron number density across the wake edge showed that, after correction for the spatial separation of the sensors, the charge particle number densities declined into the wake at a faster rate than that predicted by theoretical models. At angles of more than 10° into the wake from its geometric edge we find two electron populations having different mean random energies and electrical potentials. One of these populations is suggested to be the result of selective filtering of the high energy tails of the ambient ionospheric population, the other a result of photo‐emission from the payload bay surfaces.

Results from the vehicle charging and potential experiment on STS-3

The Vehicle Charging and Potential Experiment formed part of the scientific experiments comprising the NASA Office of Space Sciences-1 pallet flown at an altitude of 250 km and an orbital inclination of 40 deg on the third flight of the Space Shuttle Orbiter in March 1982. Details of the objectives, the instrumentation of the experiment, and some preliminary results from the individual instruments are presented. The experiment studied passive vehicle charging using thermal plasma probes, and it is concluded that apart from moderate v x B (L)-induced electrical potential resulting from the large size and restricted plasma contact area, the Space Shuttle Orbiter behaved similarly to smaller spacecraft orbiting in the same ionospheric region. However, an unexpected passive orbital result was the detection of enhanced plasma density in the vicinity of the Orbiter under restricted orbital conditions, apparently composed of contaminant molecular species and with an electron component having a temperature considerably higher than the ambient ionosphere electrons. The active vehicle charging experiments were performed by using a 100 mA/1 keV electron beam emitted out of the payload bay. Charging measurements made during short electron beam pulse emissions provide an upper limit of about 1 mF for the Orbiter capacitance. Steady-state charging measurements showed that for the vehicle attitudes covered by the mission, the induced electrical potential was normally only a few volts, except during some nighttime conditions when it rose above 40 V.

Plasma interactions in the space shuttle orbiter environment

Attempts to measure the ambient ionospheric plasma environment in the vicinity of the payload bay of the Space Shuttle Orbiter have shown that the plasma is quite different, in a variety of characteristics, from the ionospheric plasma at low earth orbit altitudes. It appears that the large size, complex geometry and various outgassing characteristics of a typical Orbiter payload can all contribute to modifications of the plasma environment of the Space Shuttle Orbiter. The measurements indicate that the plasma is often quite turbulent and contains populations more energetic than the ambient ionospheric plasma. Pronounced wake and ram effects have been observed, and at times the data can be interpreted as plasma number density enhancements of an order of magnitude or greater over the ambient, undisturbed plasma concentration. There is evidence that this enhanced plasma concentration contains molecular ions, not occurring naturally at low earth orbit altitudes. In addition to describing the observations, the electrodynamics of enhanced Orbiter-generated plasma and its possible impact on optical measurements from the Space Shuttle Orbiter will be discussed.

Measurements of background gamma radiation on Spacelab 2

A Nuclear Radiation Monitor (NRM) was flown as part of the verification instrumentation on the Spacelab 2 mission, July 29 – August 6, 1985. The monitor is a 12.7 cm diameter, 12.7 cm thick NaI(Tℓ) scintillation detector surrounded by a charged particle detector. The NRM, mounted on a pedestal near the rear of the payload bay, has a nearly omnidirectional response. Gamma rays are detected with high efficiency over the energy range 0.06 to 30 MeV. The monitor operated throughout most of the mission, recording spectra every 20 seconds and counting rates in coarse energy bands on finer timescales. The gamma radiation environment on Spacelab consists of cosmic-ray and trapped proton secondary radiation in the Spacelab/Shuttle, Earth albedo radiation, and delayed induced radioactivity in the detector and surrounding materials. Passages through the South Atlantic Anomaly protons produce a well-defined background enhancement. Episodes of greatly increased background due to trapped electrons are seen on many passes through high latitudes. This background has a soft spectrum, characteristic of bremsstrahlung radiation. These enhancements often have complex temporal structure.

Correction to “The shuttle environment: Effects of thruster firings on gas density and composition in the payload bay”

Correction to “The shuttle environment: Effects of thruster firings on gas density and composition in the payload bay”

Companion - An economical adjunct to the Space Shuttle

A 'Companion' system which would operate with the Space Shuttle to provide lower cost transportation is proposed. The companion system operation would involve launching simultaneously with the Shuttle, booster fly back to the launch site for reuse, payload delivery, rendezvous with the Shuttle, and reentry in the payload bay of the Orbiter. The disadvantages of this system are that the Orbiter could return only the Companion in its payload bay and the Orbiter may need to remain in orbit extra days; however, the economic benefits of the system are significant. It is estimated that the system could deliver a payload and shroud mass of about 10,000 kg into low earth orbit.

Nitrogen dioxide emitted from space shuttle surfaces and shuttle glow

Photographs taken on early space shuttle flights have indicated the presence of a surface glow in the ram direction1. Examination of airglow data from the AE and DE satellites has shown, the presence of a similar glow2, suggesting that the phenomenon is general to spacecraft in low Earth orbit, with the emission being concentrated in the ram direction. Several explanations have been offered for the glow: (1) OH formed by surface reactions of fast 0 atoms3; (2) plasma discharge mechanism4; (3) surface-induced decomposition of N2 followed by recombination into an excited state5; (4) surface emission by impact of O2 and O (ref. 6); and (5) near-continuum emission (at a resolution of ∼3.4 nm) in the region 400–800 nm from electronically excited NO2 (ref. 7). With reference to the last hypothesis we discuss here data on the number density of NO2 measured inside the payload bay of the shuttle orbiter. We also derive fluxes of NO2 near shuttle surfaces. Our data are shown to be consistent with the hypothesis of the glow being caused by NO2 emission.

The shuttle environment: Effects of thruster firings on gas density and composition in the payload bay

In order to study the gaseous environment of the STS orbiter a mass spectometer was operated aboard the SPAS‐01 subsatellite on the shuttle missions STS 7 and 41‐B. Data are reported on the impact of the operation of attitude control thrusters on the atmosphere in the payload bay. Firings of aft mounted thrusters have been observed to increase the total number density inside the payload bay to more than 1018 m−3 (equivalent to more than 7×10−5 mbar), whereas the operation of most of the forward mounted thrusters yields hardly a detectable signal. Nitric oxide is a major gaseous constituent inside the payload bay during the operation of aft mounted thrusters. Water desorbing from surfaces leads to a slowly decaying total number density following engine shutdown.

The Shuttle environment - Gases, particulates, and glow

Introduction T HE growing number of Space Shuttle missions has presented the aerospace community with an unprecedented body of data on the Shuttle environment itself, as well as new data on astrophysical domains far from the Earth. This paper focuses attention on selected Shuttle environmental phenomena that may impact plans for future observations from the Shuttle platform. In this review data from STS 2-4 which have recently become available will be compared and contrasted. These data have all been presented previously, although not largely in the open literature. Among the many environmental factors that will interest users of the Shuttle, three factors have been selected that must be reckoned with for a broad range of instruments and measurements:; gases, particulates, and vehicle glows. We leave aside other issues such as mechanical structure, vibroacoustics, thermal excursions, electromagnetic interference, and materials degradation; the first three of these appear to be well understood at this time, and the last two are active research 'areas. Gases, such as H2O, surrounding the Shuttle can potentially absorb light from astronomical sources giving false, partially attenuated spectra (visible, i.r.), and can contaminate those types of particle/optical detectors that are open to the vacuum. Particulate matter can settle out on optical surfaces, reducing their transmission, and can scatter unwanted light from the sun or the Earth into the line of sight of a telescope. Vehicle glows may stand in the way of a telescopic line of sight, adding spurious signals and limiting the sensitivity of astronomical or Earth observations. While a great deal of attention has been given to the Shuttle environmental parameters as potential problems for Shuttle users, we wish to stress that so many of the original requirements on the Shuttle have been met that perhaps undue emphasis can now be seen to have been given to these problem areas. This emphasis may have been strong enough to make it hard for users to know, a priori, that the Shuttle is, in fact, a working spaceship ready to convey many successful instruments into space over the years ahead. Two elements currently important for users of the Shuttle are 1) to have a candid and complete description of the environment in the pay load bay on-orbit, controversies notwithstanding, and 2) to make sure that the Shuttle environment is not only consistent with any given set of measuring instruments but also steadily improves with successive launches. In an effort in this direction, Scialdone has recently presented a baseline model for the gaseous and particulate environment of the Shuttle bay. The developing Shuttle bay data base provides both a test bed for such models and a means for extending them. In this paper we concentrate on the data (and interpretation thereof) from various early STS flights, with regard to the gaseous envelope surrounding the Shuttle, the particle populations in orbit with the Shuttle, and the optical interferences from local (rather than astronomical) sources. It seems that many design goals for the on-orbit environment have been met. On the other hand, the environment is very variable, depending upon angle of attack, thruster events, water dumps, solar angle, and payload bay activities. We will attempt to highlight the role of these effects whenever possible.

The Space Shuttle

Publisher Summary This chapter discusses the different aspects of Space Shuttle. The Space Shuttle orbiter Columbia flew for the first time on April 12, 1981. The Canadian-built Remote Manipulator System performance during the STS-7 mission was flawless as it achieved the first deployment and retrieval of a spacecraft, the West German Shuttle Pallet Satellite from the cargo bay. Additional scientific experimentation was accomplished on STS-7 with NASA's office of Space and Terrestrial Applications payload that remained fixed inside the payload bay to perform materials processing experiments. While the Shuttle flights have been demonstrating a large number of engineering accomplishments, the capabilities of the shuttle to provide outstanding scientific benefits have also been illustrated. The Multipurpose Experiment Support Structure was used on the OAST-1 mission, an experiment involving deployment of large structures in space and the Large Format Camera. The Shuttle revolution has also made it possible to offer space experimentation opportunities to new classes of investigators through small Self Contained Payload Program better known as Getaway Specials.

A Shuttle Derived Utility Vehicle for Delivery of Small Payloads to Orbit

A small-payload utility-vehicle (UV) configuration for the Space Shuttle is proposed and illustrated with drawings, diagrams, and graphs, and tables. The primary modification to the Shuttle involves removal of the solid-rocket boosters and addition of three Shuttle main engines to the external tank, resulting in an overall weight reduction from about 4.53 to 2.07 Mlbs and a per-flight cost savings of 16 percent. For current Shuttle parameters, such a UV could carry up to 2 klbs of payload in the forebody mid-deck, the entire payload bay being occupied by fuel tanks with capacity 180 klbs; with advanced-technology weight reductions of 15 percent in Orbiter subsystem dry weights (including structures), the UV could carry up to 17 klbs of payload using only 125 klbs of internally loaded propellants, allowing a 15-ft cargo space.

Launchlog '84: NASA Embarks on Its Busiest Year

Launchlog '84: NASA Embarks on Its Busiest Year

A comparison of measured and predicted sound levels in the space shuttle payload bay

An analytical model to predict space‐average sound levels in the payload bay of the Space Shuttle at lift‐off has been developed using power balance methods. The development of the model has been reported earlier [L. D. Pope and J. F. Wilby, J. Acoust. Soc. Am. 62, 906–911 (1977)]; it is now possible to compare the predictions of the model with data from the first three launches. Space‐average sound levels in the bay were estimated from measured data and the resulting spectra compared with predictions; discrepancies were observed in the frequency range above 125 Hz. Modifications made to the analytical representation for the payload bay door resulted in much better agreement between measured and predicted sound levels. Payloads present in the bay were modeled analytically, but the predicted effects on space‐average sound pressure levels were small because of the small size of the payloads. [Work performed under NASA Contract NAS5‐26570.]

Science and technology results from the OSS-1 payload on the Space Shuttle

The OSS-1 Payload of nine experiments was carried on the STS-3 Space Shuttle flight in March of 1982. The OSS-1 Payload contained four instruments that evaluated specific aspects of the Orbiter's environment, including the levels of particulate, gaseous and electromagnetic emissions given off by the Orbiter, and the interactions between the Orbiter and the surrounding plasma. In addition to these environmental observations, these instruments performed scientific investigations in astronomy and in space plasma physics, including active experiments in electron beam propagation. Other experiments were in the areas of solar physics, plant growth, micrometeorite studies and the technology of actively controlled heat pipes. We present the initial results from these experiments, with some implications of these results for future operation of space experiments from the Shuttle payload bay. One major result was the unexpected discovery of a faint surface-induced optical glow created near the Shuttle surfaces by impacts of ambient atmospheric atoms and molecules.

The dynamics of the space shuttle orbiter with a flexible payload

The Space Shuttle Orbiter will be used as an orbital base for near-term space operations. Its payloads will range from compact satellites to large, flexible antennas. This paper addresses the problem of the dynamics and control of the Orbiter with a flexible payload. Two different cases are presented as examples. The first is a long, slender beam which might be used as an element in a large orbiting structure. The second is a compact satellite mounted on a spin table in the Orbiter payload bay. The closed loop limit cycles are determined for the first payload and the open loop eigenvalues are calculated for the second. Models of both payloads are mechanized in a simulation with the Shuttle on-orbit autopilot. The vehicle is put through a series of representative maneuvers and its behavior analyzed. The degree of interaction for each payload is determined and strategies are discussed for its reduction.

Optimization using sensitivity analysis

T paper describes a general sensitivity analysis and design optimization approach. The approach is presented by example as used in optimizing the structural shell used for the airborne support equipment which supports the inertial upper stage in the Space Shuttle (orbiter) payload bay. The paper illustrates that major improvements in design can be made with a simplified sensitivity analysis.

Specular effects of Shuttle Orbiter radiators on a typical payload

Analyses performed to determine the Space Shuttle's payload bay thermal environment generally consider all external surfaces of the Orbiter and its payload to reflect energy diffusely. However, the Orbiter's active thermal control system (ATCS) radiators util ize highly specular silverized Teflon on their outer surfaces. This study considers solar energy specularly reflected from these radiators on a typical deployed payload which extends outside the paySoad bay envelope. Parameters investigated include the degree of specularity of the radiators and the solar inclination angle with respect to the radiators. Comparisons are made between payload environmental heat flux levels assuming both diffuse and specular radiators.

The pinhole/occulter facility

The Pinhole/Occulter Facility concept uses a remote occulting mask to provide high resolution observations of the solar corona and of astronomical X-ray sources. With coded-aperture and Fourier-transform techniques, the Pinhole/Occulter makes images at a resolution of 0.2 arc sec for 2 - 120 keV X-rays, using a 50-m boom erected from the payload bay of the Space Shuttle or mounted on a free-flying platform. The remote occulter also creates a large shadow area for solar coronal observations; the Pinhole/Occulter concept includes separate optical and ultraviolet telescopes with 50-cm apertures. These large telescopes will provide a new order of resolution and sensitivity for diagnostic observations of faint structures in the solar corona. The Pinhole/Occulter is a powerful and versatile tool for general-purpose X-ray astronomy, with excellent performance in a broad spectral band complementary to that accessible with AXAF. The large collecting area of 1.5 m2 results in a 5σ detection threshold of about 0.02 μJy for the 2 - 10 keV band, or about 10−5 ph(cm2sec keV)−1 at 20 keV.

Space Shuttle Payload Bay acoustics

The successful first flight of the Space Shuttle leads to the next important task of carrying payloads safely into orbit. Seven microphones, four internal and three external, were set up to record acoustic noise in the Orbiter Payload Bay. These microphones recorded data for a short duration firing of the Space Shuttle Main Engines (SSME) only, without the Solid Rocket Boosters (SRB). The same microphones then recorded the space flight data that included the firing of both the SSME's and SRB's. These data will be compared with the NASA requirement and analytical prediction. The original assumptions and procedure to predict the internal noise of the Orbiter Payload Bay will also be reviewed.