Cosmos 2044 was the seventh Soviet biosatellite to orbit the Earth with joint U.S./U.S.S.R. experiments onboard. The mission was launched from Plesetsk on September 15, 1989. The spacecraft was recovered on September 29 after flying for 14 days. Hungary, the German Democratic Republic, Canada, Poland, Great Britain, France, Romania, Czechoslovakia, and the ESA also participated in the mission.
The joint U.S./U.S.S.R. experiments were conducted on 2 rhesus monkeys and 10 rats that were flown onboard the Cosmos 2044 biosatellite. The biological payload also included fish, amphibians, insects, worms, protozoans, cell cultures, and plants. Many of the studies conducted on the biosatellite were repeats of experiments flown previously on Cosmos 1887. The results from many of those experiments were inconclusive because of the delay in recovering the biosatellite. Consequently, the experimental subjects had partially readapted to Earth gravity before postflight testing could be performed.
The Rat Biospecimen Sharing Program included 43 experiments conducted by U.S. scientists on tissues from the flight rats. The goal of the program was to extend the investigations conducted aboard the Cosmos 1887 biosatellite, with a shorter specimen recovery period. Methodologies used in Cosmos 1887 experiments were duplicated and extended to maximize comparability. Among these were studies of the effects of microgravity on various tissues such as the heart, lungs, small intestine, liver, muscle, bone, connective tissue, and testes. Experiments were also carried out to determine the response of the immune and endocrine systems to space flight. Other studies were concerned with processes such as tissue repair and skeletal growth in the space environment. The primates flown on the spacecraft acted as experimental subjects for five studies that dealt with the effects of space flight on neurovestibular, behavioral, muscular, circadian rhythm, metabolic, and thermoregulatory responses. Another experiment was performed, without using biological subjects, to evaluate the radiation environment inside and outside the spacecraft.
Primate experiments were conducted in flight on two male Rhesus monkeys (Macaca mulatta) named Zhakonya and Zabiyaka. These and other control monkeys were implanted with several electrodes and sensors for recording physiological parameters.
Subjects for the rat experiments were male specific pathogen free Wistar rats. The flight group and each of 3 control groups contained 10 rats. Five of the rats in each group were surgically treated so that tissue repair in space could be studied. Apart from the synchronous control and the vivarium control experiments, another control was carried out on this mission. The rats in this third control group were placed in individual cages and suspended by their tails in a head-down position, so that the weight of the lower body was supported by the forelimbs. The objective was to remove static loads from the hindlimbs and thereby to simulate the physiological changes that occur in microgravity. Preflight data were obtained from a basal control group of 10 untreated rats. Diet, temperature, humidity and lighting for this group were kept consistent with conditions expected in flight. Rats in this group were euthanized at the time of launch in order to obtain baseline tissue samples.
The monkey subjects were housed in flight in two primate BIOS units, similar to the ones used in previous Cosmos missions (see the Cosmos 1514 section). The food/juice dispenser nozzle was modified to prevent the malfunction that occurred on Cosmos 1887. A great deal of hardware was used in conducting the preflight, in-flight, and postflight primate experiments. The U.S.S.R. provided much of this hardware. The U.S. developed flight hardware for the circadian rhythm/thermoregulation experiment, two ambient temperature recorders for the radiation dosimetry experiment, various ground support hardware for the other experiments, and temperature-controlled biotransporters for transferring specimens from the U.S.S.R. to the U.S.
Several sensors were used to obtain data for the circadian rhythm/thermoregulation experiment. Motor activity was monitored by a piezoelectric sensor attached to each monkey's jacket. Thermistors attached to the monkeys at three different positions yielded data on skin temperature. Two thermistors attached to the top and bottom of each primate chair provided ambient temperature values. The Soviets provided additional data on axillary temperature and heart rate. All data required for the experiment were recorded on a self-contained signal processing and digital data storage device. An interface box was used to connect the sensors to the signal processor. A ground readout unit was developed for the experiment to test signal processor operation, initiate data sampling, and recover data from the signal processor. A signal simulator provided simulated biological signals for testing the flight hardware on the ground.
Two magnetic scleral search coils were surgically implanted in the right eye of flight and control monkeys for one of the neurovestibular experiments. Eye movements were recorded preflight and postflight in response to vestibular and optokinetic stimuli provided by a rotator with a three-axis optokinetic stimulator. Recordings of eye movement were made with the animals in an upright position and at several angles of tilt with respect to the gravitational axis of the Earth. The optokinetic stimulator consisted of a light device that projected moving shapes onto a domed screen surrounding the animals' visual field (Fig. 4-45). Movement of shapes at different speeds allowed the animals to be exposed to varying surround velocities. During these preflight and postflight studies, animals were kept in primate chairs with modified head restraint. Eye movement recordings were calibrated by means of an eye coil system. Data were recorded on videotapes and computer disks.
Flight and control monkeys were also implanted with head restraint devices, eye movement electrodes, and neural afferent recording systems. The intent was to measure eye position and discharges from semicircular canal and otolith afferents in response to complex vestibular stimulation. These vestibular parameters were measured periodically during space flight. Vestibular stimulation for preflight and postflight ground studies was provided by rotating the primate chairs on a computer-controlled motor-driven rotator (Fig. 4-46). In flight, preflight, and postflight data were exchanged between the U.S. and the U.S.S.R.
EMG implants were made in the soleus, medial gastrocnemius, and tibilias anterior muscles of the flight and control monkeys by Soviet specialists. Raw EMG data were copied from the Soviet primary data tapes onto tapes provided by the U.S. The U.S. supplied a primate restraint chair and equipment for the postflight muscle biopsy procedure. No experimental hardware was required in flight for the primate metabolism experiment or the rat studies. Ground support equipment for injecting primates with doubly labeled water for the metabolism experiment and for processing and transporting specimens was provided by the U.S.
The U.S. supplied four biotransporters for transferring specimens in temperature-controlled environments. Two of these were thermoelectric units used to move specimens by aircraft from the biosatellite recovery site to Moscow. They were designed to maintain internal temperatures of 23°C and 4°C. In addition, two passive biotransporters were used to maintain specimens at about 4°C and at -70°C during the transfer from Moscow to ARC.
Considerable effort was invested in developing hardware for the radiation dosimetry experiment. Two four-channel ambient temperature recorders were developed for the study. These were small, self-contained, battery-operated units that were mounted on the outside of the spacecraft to measure and record temperature data at pre-selected sampling rates on one to four channels. The data were stored in solid-state memory and readout postflight through a ground-based computer. The remarkable feature of the recorder was its ability to measure temperatures ranging from -50°C to 50°C with an accuracy of ±1°C and a resolution of 0.5°C. Other hardware required for the experiment included several radiation dosimeters located both external and internal to the spacecraft, and some nuclear track detectors located external to the spacecraft.
As mentioned previously, there were four types of control experiments performed in support of the in-flight rat studies. Synchronous and vivarium control studies were conducted as in earlier Cosmos flights. A basal control group provided baseline preflight data. A tail suspension control group furnished data in simulated space flight conditions. Small skin, bone, and muscle wounds were surgically created in the hindlimbs of five of the flight rats two days before flight, so that in-flight tissue repair could be studied. At launch, all rats were approximately 14 weeks old. Preflight procedures for the circadian rhythm/thermo- regulation experiment consisted of developing and verifying the sensor attachment method, restraint testing of monkeys, sensor implantation, conditioning subjects to skin sensor attachment, and conduct of experiment verification and bioengineering tests. For the neuromuscular study, EMG recordings were made and muscle biopsies were taken from non-instrumented limbs. The U.S. scientist in charge of the radiation dosimetry experiment assembled flight and ground control dosimeter units. They were shipped to the U.S.S.R. and mounted inside and outside the biosatellite.
No in-flight data were obtained from the rats flown on the biosatellite other than group measurements of food and water consumption. Combined U.S. and Soviet measurements made on the primates during the in-flight period included skin temperature, axillary temperature, motor activity, heart rate, metabolic rate, EMG activity, recordings of eye and head movements, and nerve activity. The clamshell cover on the dosimeter compartment outside the spacecraft was kept open during launch. Continuous measurements were made during the period spent in orbit. The cover was closed for biosatellite re-entry.
The flight subjects were recovered from the landing site with minimal delay. Flight rats were euthanized between five and eight hours after landing. Rats in all experimental groups were euthanized at the same time of day. Tissues were collected and preserved as stipulated by individual experiments.
Muscle biopsies were taken from the same sites in rats and monkeys, and these data were subsequently compared to biopsies taken from astronauts. Postflight studies were conducted on the monkeys to obtain EMG and neurovestibular data. Immediately after biosatellite recovery, radiation dosimeters were placed in a lead-lined case and transported to Moscow along with the temperature recorders.
The two flight monkeys tolerated the flight well. An average of 65 percent of the preflight daily food intake was consumed by the monkeys during the in-flight period. The lower food intake was thought to be related to a decreased energy expenditure in microgravity.
When the BIOS-vivaria unit was opened at the recovery site the rats were active and in good condition. No pathological effects were found in the rats, but changes were seen in various body systems. Regional changes were noted in bone. Plasma levels of calcitonin had decreased and parathyroid hormone levels had increased. Changes found in muscle included decreased mass and fiber cross-sectional area, fewer slow-twitch fibers, and more fast-twitch fibers. Changes were measured in levels of various muscle enzymes and in protein and RNA levels. Cardiac studies showed that a number of changes had occurred in heart structure and chemistry. Changes were also found in hormone levels, metabolism, and the immune, nervous, and reproductive systems. Both muscle and bone repair processes appeared to be inhibited after space flight.
For the first time, in-flight temperatures were recorded for radiation dosimeters located outside the biosatellite. These measurements were very useful for interpreting radiation dose data.
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Connolly, J.P., R.E. Grindeland, and R.W. Ballard. U.S. Monkey and Rat Experiments Flown on the Cosmos 2044 Biosatellite. Final Reports. NASA TM-108802, September 1994.
Grindeland, R.E., R.W. Ballard, J.P. Connolly, and M.F. Vasques. Cosmos 2044 Mission: Overview. Journal of Applied Physiology, vol. 73, no. 2, August 1992, pp. 51-53.
Morey, E.R. Spaceflight and Bone Turnover: Correlation with a New Rat Model of Weightlessness. Bioscience, vol. 29, 1979.