The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on RBSP

The Electric and Magnetic Field Instrument and Integrated Science (EMFISIS) investigation on the NASA Radiation Belt Storm Probes (now named the Van Allen Probes) mission provides key wave and very low frequency magnetic field measurements to understand radiation belt acceleration, loss, and transport. The key science objectives and the contribution that EMFISIS makes to providing measurements as well as theory and modeling are described. The key components of the instruments suite, both electronics and sensors, including key functional parameters, calibration, and performance, demonstrate that EMFISIS provides the needed measurements for the science of the RBSP mission. The EMFISIS operational modes and data products, along with online availability and data tools provide the radiation belt science community with one the most complete sets of data ever collected.     

Interplanetary Coronal Mass Ejections Observed in the Heliosphere: 1. Review of Theory

With the recent advancements in interplanetary coronal mass ejection (ICME) imaging it is necessary to understand how heliospheric images may be interpreted, particularly at large elongation angles. Of crucial importance is how the current methods used for coronal mass ejection measurement in coronagraph images must be changed to account for the large elongations involved in the heliosphere. In this review of theory we build up a picture of ICME appearance and evolution at large elongations in terms of how it would appear to an observer near 1 AU from the Sun. We begin by revisiting the basics of Thomson scattering describing how ICMEs are detected, in this we attempt to clarify a number of common misconceptions. We then build up from a single electron to an integrated line of sight, consider the ICME as a collection of lines of sight and describe how a map of ICME appearance may be developed based on its appearance relative to each line of sight. Finally, we discuss how the topology of the ICME affects its observed geometry and kinematic properties, particularly at large elongations. This review is the first of a three-part series of papers, where a review of theory is presented here and a model is developed and used in subsequent papers.     

Interplanetary Coronal Mass Ejections Observed in the Heliosphere: 3. Physical Implications

We conclude the heliospheric image series with this third and final instalment, where we consider the physical implications of our reconstruction of interplanetary coronal mass ejections from heliospheric imagers. In Paper 1 a review of the theoretical framework for the appearance of ICMEs in the heliosphere was presented and in Paper 2 a model was developed that extracted the three-dimensional structure and kinematics of interplanetary coronal mass ejections directly from SMEI images. Here we extend the model to include STEREO Heliospheric Imager data and reproduce the three-dimensional structure and kinematic evolution of a single Earth-directed interplanetary coronal mass ejection that was observed in November 2007. These measurements were made with each spacecraft independently using leading edge measurements obtained from each instrument. We found that when data from the three instruments was treated as a single collective, we were able to reproduce an estimate of the ICME structure and trajectory. There were some disparities between the modelled ICME and the in situ data, and we interpret this as a combination of a slightly more than spherically curved ICME structure and a corotating interaction region brought about by the creation of a coronal hole from the CME eruption. This is the first time evidence for such a structure has been presented and we believe that it is likely that many ICMEs are of this nature.     

The relative role of visual and non-visual cues in determining the perceived direction of "up": experiments in parabolic flight

In order to measure the perceived direction of "up", subjects judged the three-dimensional shape of disks shaded to be compatible with illumination from particular directions. By finding which shaded disk appeared most convex, we were able to infer the perceived direction of illumination. This provides an indirect measure of the subject's perception of the direction of "up". The different cues contributing to this percept were separated by varying the orientation of the subject and the orientation of the visual background relative to gravity. We also measured the effect of decreasing or increasing gravity by making these shape judgements throughout all the phases of parabolic flight (0 g, 2 g and 1 g during level flight). The perceived up direction was modeled by a simple vector sum of "up" defined by vision, the body and gravity. In this model, the weighting of the visual cue became negligible under microgravity and hypergravity conditions.     

Orbiting Platform Communication and Data Management Systems

The communications and tracking (C&T) system on board the orbiting platform communicates with the ground facilities through the TDRS satellites. The C&T system operates on Ku and S-band. Using a high gain antenna the Ku-band channel can support a downlink data rate of 300 Mbps through the TDRS single axis channel. The S-band system communicates with the orbiter and with both multiple and single axis TDRS channels. The Data Management System (DMS) provides the following services to the orbiting platform: data distribution within and between core systems and payloads, data processing facilities for core systems, data base management, time and frequency standards, and overall platform management and control. The DMS is a distributed data processing network. The nodes are connected by a local area network (LAN). Each node is autonomous. Since the design is modular, nodes can be added or deleted without disturbing the system. Sensors and effectors communicate with the core system software via the network through multiplexers/demultiplexers.     

Germination and elongation of flax in microgravity.

This experiment was conducted as part of a risk mitigation payload aboard the Space Shuttle Atlantis on STS-101. The objectives were to test a newly developed water delivery system, and to determine the optimal combination of water volume and substrate for the imbibition and germination of flax (Linum usitatissimum) seeds in space. Two different combinations of germination paper were tested for their ability to absorb, distribute, and retain water in microgravity. A single layer of thick germination paper was compared with one layer of thin germination paper under a layer of thick paper. Paper strips were cut to fit snugly into seed cassettes, and seeds were glued to them with the micropyle ends pointing outward. Water was delivered in small increments that traveled through the paper via capillary action. Three water delivery volumes were tested, with the largest (480 microliters) outperforming the 400 microliters and 320 microliters volumes for percent germination (90.6%) and root growth (mean=4.1 mm) during the 34-hour spaceflight experiment. The ground control experiment yielded similar results, but with lower rates of germination (84.4%) and shorter root lengths (mean=2.8 mm). It is not clear if the roots emerged more quickly in microgravity and/or grew faster than the ground controls. The single layer of thick germination paper generally exhibited better overall growth than the two layered option. Significant seed position effects were observed in both the flight and ground control experiments. Overall, the design of the water delivery system, seed cassettes and the germination paper strip concept was validated as an effective method for promoting seed germination and root growth under microgravity conditions.     

The decay of NASA's technical culture

The ability of the US government to carry out future space policies depends upon the maintenance of a technically capable space flight agency. During its first decade of operation the National Aeronautics and Space Administration (NASA) developed an organizational culture supporting very high levels of reliability. This ‘technical culture’ stressed the importance of in-house technical capability, ‘hands on’ activity and extensive testing. Forces at work on the agency since 1970 have tended to erode the original culture. This article explains the ways in which the beliefs and norms guiding NASA operations have changed since the agency's first decade of operations.     

Loss-of-Consciousness&Spatial Disorientation Auto-Recovery System

A G-induced loss-of-consciousness (GLOC) and spatial disorientation auto-recovery system has been developed and tested on the Advanced Fighter Technology Integration (AFTI)/F-16 aircraft. The pilot controls the operation of this system by entering an MSL altitude and manually arming the system. Engagement conditions of the auto-recovery maneuver are controlled by aircraft speed, altitude, attitude, and the set recovery altitude and do not depend upon any determination of pilot physiological condition. Initiation of the recovery maneuver is preceded by visual and aural warnings which continue until the pilot resumes control. The pilot always has the capability to override or disengage the autorecovery maneuver. This system, as developed on the AFTI/F-16, is directly and quickly applicable to other analog or digital flight control systems such as found in the F-16 or F-18. This system provides the pilot protection from ground collision in most air-to-air training environments.     

The Mercury Dual Imaging System on the MESSENGER Spacecraft

The Mercury Dual Imaging System (MDIS) on the MESSENGER spacecraft will provide critical measurements tracing Mercury’s origin and evolution. MDIS consists of a monochrome narrow-angle camera (NAC) and a multispectral wide-angle camera (WAC). The NAC is a 1.5° field-of-view (FOV) off-axis reflector, coaligned with the WAC, a four-element refractor with a 10.5° FOV and 12-color filter wheel. The focal plane electronics of each camera are identical and use a 1,024×1,024 Atmel (Thomson) TH7888A charge-coupled device detector. Only one camera operates at a time, allowing them to share a common set of control electronics. The NAC and the WAC are mounted on a pivoting platform that provides a 90° field-of-regard, extending 40° sunward and 50° anti-sunward from the spacecraft +Z-axis—the boresight direction of most of MESSENGER’s instruments. Onboard data compression provides capabilities for pixel binning, remapping of 12-bit data into 8 bits, and lossless or lossy compression. MDIS will acquire four main data sets at Mercury during three flybys and the two-Mercury-solar-day nominal mission: a monochrome global image mosaic at near-zero emission angles and moderate incidence angles, a stereo-complement map at off-nadir geometry and near-identical lighting, multicolor images at low incidence angles, and targeted high-resolution images of key surface features. These data will be used to construct a global image base map, a digital terrain model, global maps of color properties, and mosaics of high-resolution image strips. Analysis of these data will provide information on Mercury’s impact history, tectonic processes, the composition and emplacement history of volcanic materials, and the thickness distribution and compositional variations of crustal materials. This paper summarizes MDIS’s science objectives and technical design, including the common payload design of the MDIS data processing units, as well as detailed results from ground and early flight calibrations and plans for Mercury image products to be generated from MDIS data.