Near Magnetic Field Investigation,Instrumentation, Spacecraft Magnetics and Data Access

The primary objective of the investigation is the search for a body-wide magnetic field of the near Earth asteroid Eros. The Near Earth Asteroid Rendezvous (NEAR) 3-axis fluxgate magnetometer includes a sensor mounted on the high-gain antenna feed structure. The NEAR Magnetic Facility Instrument (MFI) is a joint hardware effort between GSFC and APL. The design and magnetics approach achieved by the NEAR MFI effort entailed low-cost, up-front attention to engineering solutions which did not impact the schedule. The goal of the magnetometer is reliable magnetic field measurements within 5 nT, which necessitates the use of an extensive spacecraft magnetic interference model but is achievable with the full year's orbital data set. Such a goal has been shown viable with recent in-flight calibration data and comparisons to the WIND magnetometer data. The NEAR MFI effort has succeeded in providing magnetic field measurements for the first flight in NASA's Discovery line.     

The ACE Magnetic Fields Experiment

The magnetic field experiment on ACE provides continuous measurements of the local magnetic field in the interplanetary medium. These measurements are essential in the interpretation of simultaneous ACE observations of energetic and thermal particles distributions. The experiment consists of a pair of twin, boom- mounted, triaxial fluxgate sensors which are located 165 inches (=4.19 m) from the center of the spacecraft on opposing solar panels. The electronics and digital processing unit (DPU) is mounted on the top deck of the spacecraft. The two triaxial sensors provide a balanced, fully redundant vector instrument and permit some enhanced assessment of the spacecraft's magnetic field. The instrument provides data for Browse and high-level products with between 3 and 6 vector s−1 resolution for continuous coverage of the interplanetary magnetic field. Two high-resolution snapshot buffers each hold 297 s of 24 vector s−1 data while on- board Fast Fourier Transforms extend the continuous data to 12 Hz resolution. Real-time observations with 1-s resolution are provided continuously to the Space Environmental Center (SEC) of the National Oceanographic and Atmospheric Association (NOAA) for near- instantaneous, world-wide dissemination in service to space weather studies. As has been our team's tradition, high instrument reliability is obtained by the use of fully redundant systems and extremely conservative designs. We plan studies of the interplanetary medium in support of the fundamental goals of the ACE mission and cooperative studies with other ACE investigators using the combined ACE dataset as well as other ISTP spacecraft involved in the general program of Sun-Earth Connections. This revised version was published online in June 2006 with corrections to the Cover Date.     

On the Slow Solar Wind

A theory for the origin of the slow solar wind is described. Recent papers have demonstrated that magnetic flux moves across coronal holes as a result of the interplay between the differential rotation of the photosphere and the non-radial expansion of the solar wind in more rigidly rotating coronal holes. This flux will be deposited at low latitudes and should reconnect with closed magnetic loops, thereby releasing material from the loops to form the slow solar wind. It is pointed out that this mechanism provides a natural explanation for the charge states of elements observed in the slow solar wind, and for the presence of the First-Ionization Potential, or FIP, effect in the slow wind and its absence in fast wind. Comments are also provided on the role that the ACE mission should have in understanding the slow solar wind. This revised version was published online in June 2006 with corrections to the Cover Date.     

Power Generation?Some Tasks and Goals

Generating capacity additions planned for the 1970's and beyond include a high percentage of nuclear power plants. The light water reactor is the dominant type of commercial nuclear reactor being installed during the 1970's. Advancement to more efficient designs, such as the high-temperature gas-cooled reactor, is expected around 1980. Prospects for the breeder reactor and fusion energy systems dictate a major research and development effort. Attempts to control effluents from fossil-fired plants have resulted in a sharp increase in the use of low sulfur fuels. Research and development efforts are being intensified in an attempt to obtain a breakthrough in methods of stack emission control.     

高速切削在模具加工中的应用及发展趋势

叙述了高速切削技术的意义,并介绍了它在电极制造、淬硬材料型腔的直接加工及样件的快速成型中的应用及优点,并简要说明对高速铣床的要求.     

The Influence of Tilt Angle and Magnetic Field Variations on Cosmic ray Modulation

The maximum inclination of the heliospheric current sheet (the tilt angle) and the magnitude B of the heliospheric magnetic field are often used to characterize cosmic ray (CR) modulation. The relevance of B is likely to be the coupling of the interplanetary diffusion coefficients K to the field magnitude in a relation K∝B ⁻ⁿ. In this paper we study the coupled influence of tilt angle and magnetic field variations on the modulation of cosmic rays at neutron monitor energies for the 1974 mini-cycle and for the onsets of solar cycles 21, 22, and 23. It is suggested that for A>0 polarity epochs, the sensitivity of the CR response to variations in B is partly controlled by the size of the tilt angle, α. The onsets of cycles 21 and 23 exhibit differences, related to phase differences in these parameters. A simple model is used to predict the CR response to variations in B. This revised version was published online in August 2006 with corrections to the Cover Date.     

ARTEMIS Science Objectives

NASA??s two spacecraft ARTEMIS mission will address both heliospheric and planetary research questions, first while in orbit about the Earth with the Moon and subsequently while in orbit about the Moon. Heliospheric topics include the structure of the Earth??s magnetotail; reconnection, particle acceleration, and turbulence in the Earth??s magnetosphere, at the bow shock, and in the solar wind; and the formation and structure of the lunar wake. Planetary topics include the lunar exosphere and its relationship to the composition of the lunar surface, the effects of electric fields on dust in the exosphere, internal structure of the Moon, and the lunar crustal magnetic field. This paper describes the expected contributions of ARTEMIS to these baseline scientific objectives.     

The Galactic Environment of the Sun: Interstellar Material Inside and Outside of the Heliosphere

Interstellar material (ISMa) is observed both inside and outside of the heliosphere. Relating these diverse sets of ISMa data provides a richer understanding of both the interstellar medium and the heliosphere. The galactic environment of the Sun is dominated by warm, low-density, partially ionized interstellar material consisting of atoms and dust grains. The properties of the heliosphere are dependent on the pressure, composition, radiation field, ionization, and magnetic field of ambient ISMa. The very low-density interior of the Local Bubble, combined with an expanding superbubble shell associated with star formation in the Scorpius-Centaurus Association, dominate the properties of the local interstellar medium (LISM). Once the heliosphere boundaries and interaction mechanisms are understood, interstellar gas, dust, pickup ions, and anomalous cosmic rays inside of the heliosphere can be directly compared to ISMa outside of the heliosphere. Our understanding of ISMa at the Sun is further enriched when the circumheliospheric interstellar material is compared to observations of other nearby ISMa and the overall context of our galactic environment. The IBEX mission will map the interaction region between the heliosphere and ISMa, and improve the accuracy of comparisons between ISMa inside and outside the heliosphere.     

The Lunar Radar Sounder (LRS) Onboard the KAGUYA (SELENE) Spacecraft

The Lunar Radar Sounder (LRS) onboard the KAGUYA (SELENE) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on October 29, 2007. Through the operation until June 10, 2009, 2363 hours worth of radar sounder data and 8961 hours worth of natural radio and plasma wave data have been obtained. It was revealed through radar sounder observations that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Radar sounder data were obtained not only in the nearside maria but also in other regions such as the farside highland region and polar region. LRS also performed passive observations of natural plasma waves associated with interaction processes between the solar wind plasma and the moon, and the natural waves from the Earth, the sun, and Jupiter. Natural radio waves such as auroral kilometric radiation (AKR) with interference patterns caused by the lunar surface reflections, and Jovian hectometric (HOM) emissions were detected. Intense electrostatic plasma waves around 20 kHz were almost always observed at local electron plasma frequency in the solar wind, and the electron density profile, including the lunar wake boundary, was derived along the spacecraft trajectory. Broadband noises below several kHz were frequently observed in the dayside and wake boundary of the moon and it was found that a portion of them consist of bipolar pulses. The datasets obtained by LRS will make contributions for studies on the lunar geology and physical processes of natural radio and plasma wave generation and propagation.