The Welfare Effect of Organic Milk

This study analyzes the demands for organic and conventional milk at both brand level and commodity level adopting the multi-stage demand approach. The study also measures the consumer benefits from organic milk introduction and finds the welfare effect significant.Demand and Price Analysis,

Three Canted Radiator Panels to Provide Adequate Cooling for Instruments on Slewing Spacecraft in LEO

Certain free-flying spacecraft in low Earth orbit (LEO) or payloads on the International Space Station (ISS) are required to slew to point the telescopes at targets. Instrument detectors and electronics require cooling. Traditionally a planar thermal radiator is used. The temperature of such a radiator varies significantly when the spacecraft slews because its view factors to space vary significantly. Also for payloads on the ISS, solar impingement on the radiator is possible. These thermal adversities could lead to inadequate cooling for the instrument. This paper presents a novel thermal design concept that utilizes three canted radiator panels to mitigate this problem. It increases the overall radiator view factor to cold space and reduces the overall solar or albedo flux absorbed per unit area of the radiator

Using Pre-melted Phase Change Material to Keep Payload Warm without Power for Hours in Space

During a payload transition from the transport vehicle to its worksite on the International Space Station (ISS), the payload is unpowered for up to 6 hours. Its radiator(s) will continue to radiate heat to space. It is necessary to make up the heat loss to maintain the payload temperature above the cold survival limit. Typically an interplanetary Probe has no power generation system. It relies on its battery to provide limited power for the Communication and Data Handling (C&DH) subsystem during cruise, and heater power is unavailable. It is necessary to maintain the C&DH temperature above the minimum operating limit. This paper presents a novel thermal design concept that utilizes phase change material (PCM) to store thermal energy by melting it before the payload or interplanetary Probe is unpowered. For the ISS, the PCM is melted by heaters just prior to the payload transition from the transport vehicle to its worksite. For an interplanetary Probe, the PCM is melted by heaters just prior to separation from the orbiter. The PCM releases thermal energy to keep the payload warm for several hours after power is cut off

Using Paraffin PCM to Make Optical Communication Type of Payloads Thermally Self-Sufficient for Operation in Orion Crew Module

An innovative concept of using paraffin phase change material with a melting point of 28 C to make Optical Communication type of payload thermally self-sufficient for operation in the Orion Crew Module is presented. It stores the waste heat of the payload and permits it to operate for about one hour by maintaining its temperature within the maximum operating limit. It overcomes the problem of relying on the availability of cold plate heat sink in the Orion Crew Module

Using Paraffin PCM for Thermal Management of BOLAS Planetary CubeSats with Ion Thrusters

The Bi-sat Observations of the Lunar Atmosphere above Swirls (BOLAS) is a NASA planetary CubeSat mission concept in low lunar orbit. The BOLAS lower CubeSat is at a 90 km altitude above the lunar surface during spiraling down from the Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) to the Moon. Without phase change material (PCM), the worst hot case temperature prediction for the Command and Data Handling (C&DH) exceeds the 61C maximum operating limit, and those for the Iris solid state power amplifier (SSPA) and transponder exceed the 50C maximum operating limit. Miniature n-Tricosane PCM packs on the Iris SSPA and transponder, and miniature n-Hexacosane PCM packs on the C&DH are used to store thermal energy in sunlight and release it in the eclipse. With paraffin PCM, all the temperatures are within the maximum operating limits

Solar Probe Plus MAG Sensor Thermal Design for Low Heater Power and Extreme Thermal Environment

The heater power available for the Solar Probe Plus FIELDS MAG sensor is less than half of the heritage value for other missions. Nominally the MAG sensors are in the spacecraft's umbra. In the worst hot case, approximately 200 spacecraft communication downlinks, up to 10 hours each, are required at 0.7 AU. These downlinks require the spacecraft to slew 45 deg. about the Y-axis, exposing the MAG sensors and boom to sunlight. This paper presents the thermal design to meet the MAG sensor thermal requirements in the extreme thermal environment and with low heater power. A thermal balance test on the MAG sensor engineering model has verified the thermal design and correlated the thermal model for flight temperature predictions

Using Loop Heat Pipes to Minimize Survival Heater Power for NASA's Evolutionary Xenon Thruster Power Processing Units

A thermal design concept of using propylene loop heat pipes to minimize survival heater power for NASA's Evolutionary Xenon Thruster power processing units is presented. It reduces the survival heater power from 183 W to 35 W per power processing unit. The reduction is 81%

Using Paraffin PCM, Cryogel and TEC to Maintain Comet Surface Sample Cold from Earth Approach Through Retrieval

An innovative thermal design concept to maintain comet surface samples cold (for example, 263 degrees Kelvin, 243 degrees Kelvin or 223 degrees Kelvin) from Earth approach through retrieval is presented. It uses paraffin phase change material (PCM), Cryogel insulation and thermoelectric cooler (TEC), which are commercially available