Evaluation program for secondary spacecraft cells. Initial evaluation tests of General Electric Company 4.0 ampere-hour nickel-cadmium spacecraft cells for the AMPTE satellite program

Cells found to have electrolyte leakage, internal shorts, low capacity, or inability of any cell to recover its open circuit voltage above 1.150 volts during the internal short test are addressed. The Active Magnetic Particle Tracer Explorer (AMPTE) cell design was characterized and the effects of specific mission parameters on cell life were demonstrated

Optimisation of an ultrasonic drill horn for planetary subsurface sample retrieval

Ultrasonic tools can cut through foodstuffs, biological material and other soft matter with relative ease. However, when attempts are made to cut through harder material, the rate of progress markedly declines. Under such circumstances it is sometimes necessary to reduce the frequency of the blows delivered to the target, in order to ensure that each blow exceeds the compressive strength of the material, but for space applications the small size of high-frequency ultrasonic horns is extremely attractive. This paper therefore considers the optimization of horns for exploitation of the high-frequency/low-frequency drilling technique, whereby a free-mass oscillating between the horn and the target is employed to reduce the frequency at which impulse events are delivered to the target

Evaluation program for secondary spacecraft cells: Initial evaluation tests of General Electric Company 40.0 ampere-hour nickel-cadmium spacecraft cells for the tracking data relay satellite system

Five cells provided by NASA's Goddard Space Flight Center were evaluated at room temperature and pressure (25 C plus or minus 2 C) with discharges at the 2 hour rate. Measurements of the cell containers following test, indicated an average increase of .006 inches at the plate thickness. Average end of charge voltages and pressures, and capacity output in ampere hours were determined. Three cells exceeded the voltage requirements of 1.52 volts during both c/10 charges at 20 C. All cells exceeded the voltage requirement of 1.52 volts during the 0 C overcharge test, although their end charges were below 1.50 volts. The pressure requirement of 65 psia was exceeded by both pressure transducer cells during c/10 charges at 25 C and 20 C and also during the 0 C overcharge test. The cells with pressure transducers reached a pressure of 20 psia before reaching the voltage limit of 1.550 volts during the pressure versus capacity test, and exhibited a pressure decay of 2 psia during the last 30 minutes of the 1 hour open circuit stand. Average capacity was 51.3 ampere hours

Evaluation program for secondary spacecraft cells: Initial evaluation tests of Gulton Industries, Incorporated, 9.0 ampere-hour nickel-cadmium spacecraft cells with auxiliary electrodes for the small astronomy Satellite (SAS-C)

An evaluation test program was conducted to insure that all cells put into the life cycle program are of high quality by the screening of cells found to have electrolyte leakage, internal shorts, low capacity, or inability of any cell to recover its open-circuit voltage above 1.150 volts during the internal short test. Tests and results are described

Evaluation program for secondary spacecraft cells. Initial evaluation tests of Eagle-Picher Industries, Incorporated 3.0 ampere-hour nickel-cadmium spacecraft cells

The capacity of the cells ranged from 3.58 to 3.97 amperehours during the three capacity tests. Three cells were removed from test, due to high pressure, during the C/10, 24-hour charge at room ambient temperature. The voltage requirement of 1.480 volts was exceeded by the cells during the C/10, 24-hour charge at 20 C, although the end-of-charge voltage was below this value (1.466-1.475 volts). Average capacity out during the 20 C charge efficiency test was 0.84 AH which represents 48% and is below the minimum requirement of 55%. The cells exhibited no pressure decay during the open-circuit stand portion of the pressure versus capacity test, as all cells reached their voltage limit (1.550 volts) before their pressure reached 20 psia with the highest pressure being 8 psia during charge

Evaluation program for secondary spacecraft cells - Acceptance test of Sonotone Corporation 20 ampere-hour nickel-cadmium cells

Acceptance tests of 20 ampere-hour sealed nickel-cadmium secondary spacecraft cell

Initial evaluation tests of Eagle-Picher Industries 9.0 ampere-hour nickel-cadmium spacecraft cells for the heat capacity mapping mission satellite and the stratospheric aerosol and gas experiment satellite

The results of tests to insure that all cells put into the life cycle program are of high quality are reported. The tests consisted of the following: phenolptalein leak tests, internal short test, charge efficiency test, and overcharge tests. The results of tests for 10 cells are tabulated

Evaluation program for secondary spacecraft cells: Initial evaluation tests of General Electric Company, 6.0 ampere-hour nickel-cadmium spacecraft cells for the GOES-D, E and F satellite program

The tests are to insure that all cells put into the life cycle program are of high quality by the screening of cells found to have electrolyte leakage, internal shorts, low capacity, or inability of any cell to recover its open-circuit voltage above 1.150 volts during the internal short test. Test limits specify those values at which a cell is to be terminated from charge or discharge. Requirements are referenced to normally expected values based on past performance of aerospace nickel-cadmium cells with demonstrated life characteristics. Recommendations for the improvement of the manufacturing processes are presented

Pocketqube Deorbit Times: Susceptibility to the Solar Cycle

Nowadays, as a new kind of femto-satellite with a low cost, Pocketqube has been developed to finish the space research task within the LEO region. During its lifetime the pocketqube is exposed to a high risk of collision with space debris. Taking the solar cycle as a main factor, predicting its deorbit time and evaluating its collision probability before the launch is of great importance for the mission designers to choose a right orbit and determine the proper launch time. This article presents a combined atmospheric density model based on the data from CIRA-2012 to describe the effects of the solar cycle on air density in LEO, and shows how the model is applied to calculate orbital lifetimes of pocketqubes in essentially circular equatorial orbits below 800 km altitude. Then the classical fourth order Runge-Kutta method is utilized in integrating the first order differential equations, which express the rates of change of semi major axis and eccentricity, in order to calculate the orbital lifetimes of pocketqube in LEO. The launch date within the 11-year solar cycle has been chosen as an independent variable to present the influence on lifetime prediction and probability evaluation. The result of lifetime calculation shows that the pocketqube launched at the minimum solar activity year does not necessarily get its longest lifetime. Meanwhile if the pocketqube at some specific starting altitudes is launched at the maximum solar activity year, it may remain in orbit for the longest time period. It also demonstrates how the sensitivity of pocketqube deorbit time to the launch date varies with the initial altitudes. From the figures, it can be obtained that 450 km is the altitude at which the deorbit time is most sensitive to the launch date with the percentage amplitude of 180% over its average value. Furthermore, the collision risk from space debris whose diameter is larger than 1 mm and 10 cm are evaluated by using the same method to integrate through its whole lifetime. It illustrates that for those orbits whose initial altitude is over 700 km, no matter which date is chosen to launch a pocketqube, the debris collision risk grows sharply with the starting altitude rising. Finally, by comparison with the trend of lifetime and collision risk, the interesting thing is that at some orbits with higher altitudes, like 800km, when the lifetime of the pocketqube reaches its maximum, the collision risk inversely reaches its local minimum, which can be useful for its designers to balance these two considerations

Attitude stability and altitude control of a variable-geometry Earth-orbiting solar sail

A variable-geometry solar sail for on-orbit altitude control is investigated. It is shown that, by adjusting the effective area of the sail at favorable times, it is possible to influence the length of the semi-major axis over an extended period of time. This solution can be implemented by adopting a spinning quasi-rhombic pyramidal solar sail which provides the heliostability needed to maintain a passive “sun-pointing” attitude and the freedom to modify the shape of the sail at any time. In particular, this paper investigates the variable-geometry concept through both theoretical and numerical analyses. Stability bounds on the sail design are calculated by means of a first-order analysis, producing conditions on the opening angles of the sail, while gravity gradient torques and solar eclipses are introduced to test the robustness of the concept. The concept targets equatorial orbits above approximately 5,000 km. Numerical results characterize the expected performance, leading to (for example) an increase of 2,200 km per year for a small device at GEO