The forward payload included experiments exposed to an onboard radiation source. The aft payload included experiment packages identical to those in the forward payload, but which were shielded from the radiation source. Six additional experiments for studying the effects of microgravity alone were also included in the aft payload. A tungsten radiation source holder exposed the radiation source to the forward payload during specified segments of the mission. An equipment rack located between the forward and aft payloads contained power supplies and equipment required for experiment support and recovery operations. The interior of the capsule was maintained at the equivalent of a sea-level atmosphere on Earth, within limits specified by investigators. Total pressure and partial pressure of oxygen remained constant at 14.5 psia and 146 mm mercury respectively. Relative humidity and temperature were controlled according to specified limits.

     The container for the Drosophila larvae consisted of several modules. Each module base was filled with melted culture medium before flight and a retaining sieve inserted. The larvae and live yeast were added to the module, the cover attached and the module inserted into the housing. Brackets were then placed over the eight modules in each housing. The container also had thermistors and lithium fluoride (LiF) radiation detectors.

       Four identical packages were used for the Tradescantia experiment, two for flight and two for ground control studies. Each package held 32 plants with roots sealed in a tube containing a nutrient solution. Because the flower buds were arranged in a single row, they were uniformly exposed to gamma radiation. Small holes in the cover of the package allowed air to enter, and a thermistor installed through the wall of the package registered temperature. Several passive dosimeters of LiF powder were placed in the root and bud zones of each package.

     Neurospora packages were designed so that each of the samples within would receive a different total radiation exposure. Four packages were subjected to onboard radiation at different dosages. A fifth flight package was placed in the shielded aft section of the spacecraft. Five identical packages were used in ground control experiments. The package design allowed many Neurospora spores to be contained with minimal risk of contamination and anoxia. Each spore sample was placed on a moist Millipore filter. Filters were held in place on disks with polypropylene screens. Three independent dosimeters below each filter detected backscattered radiation. A module consisted of 10 disks stacked together with barriers between adjacent disks. Assembled modules were screwed into a housing unit to complete the package.

Figure 4-7: Biosatellite II participants. (Click to enlarge)

     A plastic module with three compartments housed each group of Tribolium pupae. Each compartment contained an aluminum insert holding two felt layers sandwiched between tissue papers. One or two pupae were positioned in each of several holes punched in the pieces of felt. Four LiF dosimeters were inserted between two tissue papers with a layer of pupae on either side.

     Five packages held the Habrobracon flown on the biosatellite. Four of these were exposed to varying degrees of radiation. One was placed in the shielded portion of the spacecraft. Each package contained four modules. Habrobracon were placed in depressions in each module. After a screen was placed over the depression, the module was capped and assembled into the flight package. Three glass rod dosimeters were included in each module. Additional dosimeters consisted of LiF powder in tubes placed in front of and behind the modules. Local temperature was recorded by a thermistor located centrally between the modules.

     Two identical sets of four special packages were constructed to contain the lysogenic bacteria, one for the flight experiment and one for the ground-control experiment. One of the packages in each set contained 48 non-irradiated culture chambers. The other 3 packages each contained 16 growth chambers and were exposed to varying degrees of radiation.

Figure 4-8: The frog embryology experiment on Biosatellite II had an automatic mechanism that fixed embryos at specific times during the flight so that embryos of varying ages could be studied postflight.

     Flight hardware for the frog embryology experiment was a package of eight pairs of modules. The design of the packages was that of the frog egg experiment packages on Gemini 8 and 12. Three similar hardware packages were used in ground-control experiments. A group of 10 fertilized eggs was placed in each of the first 8 modules. Groups of five were placed in each of the remaining modules. Each module was divided into two chambers: a 10 ml egg chamber and a fixative chamber. The O-ring-fitted piston separating the two chambers was spring-loaded and actuated in pairs of modules, by program or by command. Actuation effected forceful mixing of egg medium and fixative at different times during flight for seven of the module pairs (Fig. 4-8). This process enabled the investigators to obtain eggs fixed at varying times after fertilization. Live embryos were obtained from the last pair of modules. A coolant line around the hardware package maintained the experiment at 42.5°F on the launch pad. Four thermistors in the package registered temperature. A fifth thermistor switched off the strip heaters that raised package temperature to 70°F immediately after launch.

Figure 4-9: Biosatellite II amoebae were fed with paramecia when the contents of compartments A and B were mixed. Fed amoebae were fixed when the contents of compartment C were added.

     One flight and three control units contained amoebae and paramecia (Fig. 4-9). Each unit had 24 tripartite chambers. A piston with an O-ring separated the three segments of each chamber, which contained, respectively, amoebae, paramecia, and a fixative. Initial actuation of the piston resulted in mixing of amoebae and paramecia. Further actuation mixed the amoebae and paramecia with the fixative. Four of the chambers had thermistors for measuring in-flight temperatures. High-density foam pads placed between chambers reduced the vibrations during powered flight and re-entry.

     The flight hardware unit for the wheat seedling experiments held 78 wheat seeds. It had one large chamber and three small ones. In the large chamber, 12 seeds were inserted into each of 3 polycarbonate stalks containing wetted vermiculite. The remaining seeds were contained in the three smaller chambers.Two of these chambers were equipped to spray-fix the seedlings during orbit. The seeds germinated in darkness. Thermistor records of chamber temperatures were reported periodically to the ground stations. Four additional hardware units were used in ground control experiments.

     For the pepper plant experiment, one plant was placed in each of four plant holders within the flight unit (Fig. 4-10). A three-mirror optical system and a camera allowed the top and sides of the plants to be photographed at 10-minute intervals during orbit. A clock was inserted between the top central mirrors so that each frame of the film showed the position of leaves with respect to time. Four incandescent lamps illuminated the plants for 5 seconds every 10 minutes, and facilitated photography. The unit was covered with a white sleeve during flight to maximize light use and prevent light from leaking into the biosatellite capsule. Air exchange was permitted through a series of small holes in the sleeve. Five more plants placed inside the unit later provided samples for carbohydrate, amino acid, and nitrogen analysis. Three additional hardware units were used for ground control experiments.

Figure 4-10: In the Biosatellite II pepper plant experiment, a camera recorded the positions of plant leaves with respect to time. A diagrammatic representation of the view seen through the camera (left). A side view showing experiment setup (right); A. mirror, B. clock, C. camera, D. plants.

Operations

The operations carried out to fulfill the needs of individual experiments were complex. The description below outlines the general operations performed to ensure successful launch and recovery of the biosatellite capsule.

Figure 4.-11: STADAN stations involved in controlling the launch, injection into orbit, deorbit, and recovery of the Biosatellite II. The lines indicate the path traveled by the spacecraft. (Click to enlarge)

     Although the spacecraft was designed to be flown using existing space flight services, additional operational procedures were developed because it was imperative to safely recover the biological materials onboard. The compatibility of the spacecraft system with the existing Space Tracking and Data Acquisition Network (STADAN) was successfully demonstrated. Support was enlisted from various STADAN stations in North and South America and South Africa for the operational phase of the mission (Fig. 4-11). Several facilities at Goddard Space Flight Center and Cape Kennedy were modified to meet mission requirements. Training exercises were held in the Hawaiian Islands recovery area for both an air recovery and a backup water recovery. In addition, Air Force Rescue and Retrieval Service Forces in the Azores, Bermuda, Guam, and Japan were prepared to retrieve the capsule in the event of an emergency call-down. At Cape Kennedy, compatibility between the spacecraft and the Delta launch vehicle had to be ensured.

Figure 4-12: Modification of the prelaunch sequence to accommodate a biological payload.

     The normal Delta prelaunch sequence was shortened significantly in order to preserve the integrity of the experiments on Biosatellite II (Fig. 4-12). Prelaunch activities had to be reduced or eliminated on Biosatellite II because biological materials could not be kept on the launch pad for longer than eight hours. The preparation of each experiment, the spacecraft experiment assembly, and the spacecraft launch vehicle assembly all required special detailed procedures. These procedures were strictly time-correlated with other activities such as the assembly of control experiments.

     Only a few seconds after the launch phase of the mission began, it became evident that the spacecraft was having difficulty accepting Earth commands. The system operated effectively in spite of this problem. At the end of the first complete orbit, all programmed functions were satisfactorily confirmed: the radiation source holder had opened 1 hour after launch; the pepper plants were being photographed every 10 minutes; the frog egg assembly had been appropriately heated; the amoebae had been fed with paramecia or fixed; and a frog egg module had been injected with fixative.

     Because of the impending threat of a tropical storm in the recovery area, it was decided to terminate the mission after 30 orbits instead of the planned 46. All the remaining experiment actuation commands were rescheduled and accomplished during the last five orbits. De-orbit telemetry recordings were made with the assistance of the Woomera Tracking Station in Australia.

     The flight phase of the mission was successfully concluded with the de-orbit of the recovery capsule, deployment of the parachute system, and air recovery by the U.S. Air Force on the first attempt. The subsystems in the spacecraft's adapter, which remained in orbit, were evaluated until the battery life was expended after 62 orbits.

     The 280-pound recovery capsule was returned to the temporary biological laboratories at Hickam Air Force Base in Hawaii for disassembly. Immediate inspection of the biological materials showed them to be in excellent condition.

Results

The Biosatellite II mission showed that it was feasible to operate an unmanned biology laboratory in the space environment. With very few exceptions, environment conditions imposed by experimenters were satisfied. Changes were noted in about 30 of the more than 100 biological parameters studied in the flight specimens. Radiation and flight conditions were found to interact, and, when nuclei were dividing, enhancement or synergism was found to occur in a number of different organisms. However, the relative roles of microgravity and vibration (alone or combined) as causes of this interaction were not determined.

Move to next section Biosatellite III

Halstead, T.W. and F.R. Dutcher. Status and Prospects of Experiments on Plants Grown in Space. Annals of Botany, vol. 54, supl. 3, November 1984.

Saunders, J.F. Biologic Observations from the Space Flight Missions of the United States. Presented at the open meeting of Working Group 5 of the 15th Plenary Meeting of COSPAR, "New Medical, Physiologic and General Biologic Results of Space Flight," Madrid, Spain, COSPAR Paper L.2.4, May 22, 1972.

Saunders, J.F., ed. The Experiments of Biosatellite II. NASA SP-204, 1971.

Thimann, K.V. Biosatellite II Experiments: Preliminary Results. Proceedings of the National Academy of Sciences, vol. 60, no. 2, June 1968, pp. 347-361.

Thimann, K.V. Symposium on the Biosatellite II Experiments: Preliminary Results. Bioscience, vol. 18, no. 6, June 1968.

Young, R.S. Biological Experiments in Space. Space Science Reviews. vol. 8, 1968, pp. 665-689.

Young, R.S. Experimental Biology in Space. Astronautical Engineering and Science. E. Stuhlinger, et al. eds. McGraw Hill, 1963.