Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Thu, 28 Mar 91 02:14:14 -0500 (EST) Message-ID: <4bwNT1y00WBw86UE5p@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 28 Mar 91 02:14:10 -0500 (EST) Subject: SPACE Digest V13 #312 SPACE Digest Volume 13 : Issue 312 Today's Topics: GEOMAGNETIC STORM INFORMATION UPDATE #2 - 24 MARCH Re: More cost/lb. follies Space Station Work Packages (Forwarded) Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: Sun, 24 Mar 91 12:20:57 MST From: oler%HG.ULeth.CA@BITNET.CC.CMU.EDU (CARY OLER) Subject: GEOMAGNETIC STORM INFORMATION UPDATE #2 - 24 MARCH X-St-Vmsmail-To: st%"space+@andrew.cmu.edu" /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ INFORMATIONAL MAGNETIC STORM UPDATE Storm Alert Cancellation /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ 19:00 UT, 24 March ------------- ATTENTION: The geomagnetic storm is winding down now. Geomagnetic activity began settling down around 13:00 UT on 24 March. A few low intensity minor storm level perturbations have been observed, but nothing significant has occurred now for over five hours. Geomagnetic storming peaked at severe storm levels between 03:42 UT and 06:00 UT on 24 March. Activity then became sustained at major storm levels until approximately 10:00 UT. Thereafter, activity decreased to minor storm levels and faded gradually to generally active conditions by 18:30 UT. Reports of auroral activity have been received as far south as 36 degrees north latitude over North America. Activity was reported from as far south as southern Nevada to northern Texas to North Carolina. Locations as far north as Alaska and northern Canada also witnessed significant levels of auroral activity. The Boulder A-index for 18:00 UT on 24 March is 62, which is very near the predicted levels and represents a moderate-intensity major geomagnetic storm. This storm has been classified as "Major." High latitude A-indices have been quite a bit higher (near and above 100). The storming at these latitudes has been classified as "Major to Severe." High latitude K-indices peaked at 9, while middle latitudes peaked at 8. Satellite proton and PCA activity is gradually decaying, although there will probably be several more days of satellite proton and PCA activity (barring any further major flares). HF propagation conditions have improved significantly over the past six hours. Propagation is now rated fair to good over the middle latitudes, while high and polar latitudes are still experiencing strong PCA-related absorption with periodic blackout periods and very poor propagation conditions. No reports of VHF auroral backscatter communications have been received yet, although not all of the reports are in yet. Conditions were favorable for auroral communications on VHF frequencies over high, middle and northerly low latitudes. Geomagnetic activity is not expected to intensify, although isolated periods of minor (and possibly major) storm level fluctuations are still possible during this post-storm period. Activity can be expected to increase slightly near local midnight, although widespread storming is not likely to be observed. Auroral activity has decreased in intensity and latitudinal extent. No significant low-latitude auroral activity is expected for tonight. There is a small chance for some isolated northerly low latitude auroral activity sightings, although this probability is quite low. Locations north of a line from central Oregon, central Idaho, northern Wyoming, south Dakota, southern Minnesota, southern Wisconsin, southern Michigan, southern New York and Conneticut will be more likely to witness further lower levels of auroral activity tonight (late 24 March, local time). There is still a high risk for high intensity major solar flaring from Region 6555. A major class M5.6/2B flare was observed at 22:20 UT on 23 March (at S23E06), although this flare was not large enough to produce any significant terrestrial impacts. It was impulsive and fairly radio-quiet. There is a strong possibility for another major proton flare from this region. This region will remain capable of producing high terrestrial impacts for the next four days. Renewed proton and PCA activity is possible if another proton flare occurs. Additional magnetic storming and low latitude auroral activity is possible if another major proton flare occurs. Watch for possible major flare alerts. The following alerts have been cancelled: - MAJOR GEOMAGNETIC STORM ALERT - LOW LATITUDE AURORAL ACTIVITY ALERT - ELECTRICAL GEOMAGNETIC INDUCTION ALERT The following alerts remain in progress: - SATELLITE PROTON EVENT ALERT - POLAR CAP ABSORPTION EVENT ALERT - POLAR RADIO SIGNAL BLACKOUT ALERT The following warnings remain in progress: - POTENTIAL MAJOR SOLAR FLARE ALERT - POTENTIAL PROTON FLARE ALERT /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ ------------------------------ Date: 20 Mar 91 21:17:19 GMT From: sgi!shinobu!odin!schreiber!schreiber@ucbvax.Berkeley.EDU (Olivier Schreiber) Subject: Re: More cost/lb. follies In <1991Mar20.002028.2377@dsd.es.com> bpendlet@oscar.dsd.es.com (Bob Pendleton) writes: >What if you could build it any size you want? Could you do it then? >Maybe you could. Maybe this is a rediculous example. :-) Think about >the cube-square law. If you can build any size you want then the cube >square law can give you an enormous volume to structure ratio. Maybe >good enough to build a stainless steel balloon. In this case, I think the cube-square law does not apply. Both volume and structure mass would grow as the cube of length scale: For a spherical tank, with pressure P kept constant, the force F on the greater cross section is F=P pi R^2 It must be balanced by the structure of thickness e and nominal tension strength tau: P pi R^2 = e 2 pi R tau Thus, e = P R / (2 tau) The mass of the structure is M= 4 pi R^2 e Thus, M= 4 pi R^3 P/(2 tau) For a nominal P pressurized tank of tensile strength tau, the mass is proportional to R^3, just as the mass of the fuel. >-- > Bob Pendleton, speaking only for myself. > bpendlet@dsd.es.com or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet > Tools, not rules. -- Olivier Schreiber Technical Marketing schreiber@sgi.com (415)335 7353 MS/7L580 Silicon Graphics Inc., 2011 North Shoreline Blvd. Mountain View, Ca 94039-7311 The philosophy of one century is the common sense of the next. ------------------------------ Date: 22 Mar 91 07:31:45 GMT From: mips!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@apple.com (Ron Baalke) Subject: Space Station Work Packages (Forwarded) SPACE STATION FREEDOM WORK PACKAGES Mike Simmons March 21, 1991 Marshall Space Flight Center, Huntsville (Phone: (205)544-0034) SPACE STATION FREEDOM WORK PACKAGE ONE NASA's Marshall Space Flight Center (Work Package 1) has responsibility for: the design and construction of Space Station Freedom's pressurized laboratory and habitation modules, the working area and living quarters for Freedom's crew members; the logistics modules, used for resupply and storage; node structures, which connect the laboratory and habitation modules; and certain subsystems internal to the pressurized modules, including the environmental control and life support, thermal control, electrical distribution, communcations and audio/video systems. UNITED STATES LABORATORY AND HABITATION MODULES The U.S. Laboratory Module and Habitation Module will each be 14.5 feet in diameter and 27 feet in length. These dimensions allow the modules to be built, outfitted, integrated and tested on the ground and then transported into Earth orbit in the Space Shuttle cargo bay and connected to the nodes and other space station structures. The U.S. Lab will include 15 experiment racks and 13 systems racks. During the station's Man-Tended Capability (MTC) phase, this orbiting laboratory will serve as the site for microgravity research and will be capable of conducting that science in both a manned mode, when astronauts are visiting the station via the Space Shuttle, and in an unmanned mode. When station construction reaches Permanently Manned Capability (PMC) and four astronauts remain onboard for extended periods, life sciences research will be conducted to learn more about the affects of living in space and to help prepare mankind for returning to the Moon and exploring the planets. With the addition of the Habitation and International Laboratory modules, the station's module racks will expand to as many as 45. When station construction reaches PMC and the Hab Module is added, Freedom's environmental control and lifes support systems will provide closed-loop water recycling capability. The crew's food and other supplies will be carried to the station via a logistics module which is transported in the Space Shuttle's cargo bay. During the Man-Tended Capability phase, astronauts visiting Freedom will live on the Shuttle. Kyle Herring Johnson Space Center, Houston (Phone: (713) 483-5111) SPACE STATION FREEDOM WORK PACKAGE TWO NASA's Johnson Space Center (Work Package 2) Space Station Freedom Program Office (SSPO) is responsible for the design, development, verification, assembly and delivery of the Work Package 2 flight elements and systems, which include: the pre-integrated truss assembly; propulsion assembly; Mobile Servicing System transporter; resource node design and outfitting; external thermal control; data management; communication and tracking; extravehicular systems and guidance; navigation and control systems, and the airlock. JSC SSPO is also responsible for the attachment systems required by the Space Shuttle for periodic visits. In addition, JSC SSPO provides technical direction to the Work Package 1 contractor via the Marshall Space Flight Center for the design and development of all manned space subsystems. PRE-INTEGRATED TRUSS ASSEMBLY The pre-integrated truss assembly is the Space Station Freedom structural framework to which the modules, solar power arrays and mobile transporter will be attached. PROPULSION ASSEMBLY The propulsion assembly will be used to adjust or maintain the orbit of Space Station Freedom to ensure it remains at the required altitude. Work Package 2 has responsibility for the overall propulsion system. MOBILE TRANSPORTER SYSTEM The Mobile Servicing System will be a multi-purpose mechanism equipped with a transportable robotic arm used to help assemble and maintain Space Station Freedom. The Work Package 2 contractor will build the mobile transporter; Canada will provide the robotic arm and a special-purpose dexterous manipulator. RESOURCE NODES The resource nodes house most of the command and control systems for the Space Station as well as being the connecting passageways for the habitation and laboratory modules. Work Package 2 will outfit the node structures provided by Work Package 1 to accomplish the objectives of each node. EXTRAVEHICULAR ACTIVITY SYSTEMS Extravehicular activity (EVA) systems includes equipment such as the extravehicular mobility unit (EMU) or spacesuit; provisions for communication; physiological monitoring and data transmission; EVA crew rescue and equipment retrieval provision and EVA procedures. An airlock for use by crew members performing EVA will also be designed as part of Work Package 2. EXTERNAL THERMAL CONTROL The external thermal system provides primary cooling and heat rejection to control temperatures of electronics and other Space Station hardware located throughout the facility. ATTACHMENT SYSTEMS In concert with the Orbiter Projects Office, Work Package 2 is responsible for the development of systems which will permit Space Shuttle mating with the Space Station. GUIDANCE, NAVIGATION AND CONTROL SYSTEM The GN&C system is composed of core system and traffic management functions. The core system function provides attitude and orbital state maintenance; supports the pointing of the power system and thermal radiators; accomplishes periodic reboost maneuvers, and provides Space Station attitude information to other systems and users. The traffic management function provides for controlling all traffic in the area around the Space Station, including orbiter mating operations and trajectories determination of vehicles and objects which may intersect the orbit of the Space Station. COMMUNICATIONS AND TRACKING SYSTEM The communications and tracking (C&T) system is composed of six subsystems: space-to-space communications with crew members during space walks (EVA); aboard the Space Shuttle, and with visiting vehicles such as the European Space Agency man-tended free-flyer; space-to-ground communications through the Tracking and Data Relay Satellite System (TDRSS) to ground data networks; internal and external voice communication through the audio subsystem; internal and external video requirements through the video subsystem; management of communication and tracking resources and data distribution through the control and monitor subsystem; and navigation data through the tracking subsystem. DATA MANAGEMENT SYSTEM The data management system (DMS) provides the hardware and software resources that interconnect onboard systems, payloads, and operations to perform data and information management. Functional services provided by DMS include data processing, data acquisition and distribution, data storage, and the user interface to permit control and monitoring of systems and experiments. ASSURED CREW RETURN CAPABILITY Crew safety is an essential consideration in the development of the Space Station to the permanently-manned configuration. A major system failure aboard the Space Station, injuries or illness may require the return of crew members to Earth during a period when the Space Shuttle is unavailable. NASA's Johnson Space Center has responsibility for conducting definition-phase studies of an Assured Crew Return Vehicle (ACRV) which would be used to supplement the Space Shuttle in such circumstances. WORK PACKAGE TWO CONTRACT McDonnell Douglas Space Systems Company's Space Station Division heads a team completing the work for Work Package 2. Major subcontractors include GE Aerospace Government Communications Systems Division, Honeywell Space Systems Group, IBM Federal Sector Division, Lockheed Missiles and Space Company and Astro Aerospace. GE is producing communications and tracking, Honeywell is working on stabilization and controls, IBM is designing the data management systems, Lockheed is developing thermal control, power management and distribution, and extravehicular activity systems, and Astro is responsible for the mobile transporter system. Mary Ann Peto NASA Lewis Research Center Cleveland, Ohio (216/433-2902) SPACE STATION FREEDOM WORK PACKAGE FOUR NASAUs Lewis Research Center, Cleveland, Ohio, is responsible for the end-to-end electric power system for the Freedom space station. This includes defining the system architecture and providing the solar arrays, batteries, and power management and distribution hardware and software. The power system includes power generation and storage, and the management and distribution of power to the final user interface. The electric power system is required to have the capability to deliver 22 kW of electric power for a man-tended configuration, and 65 kW for a permanently manned configuration with growth to 75.0 kW. POWER GENERATION Initially, power for Freedom will be provided by flexible, deployable solar array wings. This configuration minimizes the complexity of the assembly process by taking advantage of the technology previously demonstrated on Space Shuttle flights. Each 39-by-122 foot wing consists of two blanket assemblies covered with solar cells. These are stowed in blanket boxes which are attached to a deployment canister. Each pair of blankets is to be deployed and supported on a deployable mast. A tension mechanism will supply tension to the blanket as it reaches complete extension. The entire wing will be tied structurally to the pre-integrated truss by means of the beta gimbal assembly. In order to provide the power needed during the period of space station assembly, two solar wings, the energy storage system and electronics components are assembled into a power module scheduled to be carried up on the first space staion assembly flight. These two wings along with engergy storage will provide 22 kW of power. The remaining power modules with two solar array wings per module will be delivered on oribit after the man-tended configuration is reached. POWER STORAGE Nickel Hydrogen (Ni-H2) batteries will store the energy produced by the solar arrays. A battery pack is made up of 76 Ni-H2 cells, wiring harness, and mechanical/thermal support components. On discharge, the battery provides power to the primary bus for eclipse periods. Ni-H2 batteries were selected for low weight and high reliability. POWER MANAGEMENT AND DISTRIBUTION (PMAD) The 160/120 volt DC PMAD system is designed specifically to meet the high electric power system requirements of the space station. It is user friendly and can accommodate a wide variety of user loads delivering controlled power to many scattered loads. The high voltage DC power system was selected to provide high efficiency, low cost, and safe operations. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |___ M/S 301-355 | Change is constant. /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | |_____|/ |_|/ |_____|/ | ------------------------------ End of SPACE Digest V13 #312 *******************