Long duration exposure facility (LDEF) interplanetary dust experiment (IDE) impact detector results

1994 ◽  
Author(s):  
John P. Oliver ◽  
Charles G. Simon ◽  
William J. Cooke ◽  
S. F. Singer ◽  
Jerry L. Weinberg ◽  
...  
Keyword(s):  
Interplanetary Dust ◽  
Long Duration ◽  
Impact Detector

scholarly journals Archiving Impact Data: The LDEF IDE Database

1996 ◽  
Vol 150 ◽  
pp. 209-212
Author(s):  
K. G. Paul
Keyword(s):  
North Carolina ◽  
Interplanetary Dust ◽  
Space Science ◽  
System Level ◽  
State University ◽  
North Carolina State University ◽  
Long Duration ◽  
Analytical Instrumentation ◽  
Langley Research Center ◽  
Impact Data

After the retrieval of the NASA Long Duration Exposure Facility (LDEF), postflight investigations started on the Interplanetary Dust Experiment (IDE). The time- and orientation resolved dataset was processed at the Institute for Space Science and Technology (ISST) in Gainesville, FL, residue chemistry analyses were conducted at the Analytical Instrumentation Facility at North Carolina State University (NCSU-AIF), Raleigh, NC, and system-level tests were performed at NASA Langley Research Center (LaRC) in Hampton, VA, among other investigators. With the end of the postflight investigation program it was considered compulsory to archive all data in a format that would facilitate future analyses.

scholarly journals The LDEF Interplanetary Dust Experiment

1985 ◽  
Vol 85 ◽  
pp. 117-120
Author(s):  
S.F. Singer ◽  
J.E. Stanley ◽  
P. Kassel
Keyword(s):  
Space Shuttle ◽  
Interplanetary Space ◽  
Interplanetary Dust ◽  
Particle Energy ◽  
Meteor Streams ◽  
Space Shuttle Challenger ◽  
Long Duration ◽  
Celestial Bodies ◽  
Time Variations ◽  
Types Of Information

The Long Duration Exposure Facility was launched for the first time on April 6, 1984 by the NASA space shuttle Challenger. An array of solid-state detectors record the arrival time and approximate direction of an impacting particle. Two levels of detector sensitivity provide an indication of particle energy and mass. The active area is nearly 1 m2. We therefore expect count rates of about 30 per day over an exposure time of about a year. The orbit of the particle cannot be obtained, except statistically. We know the orientation of the detector, the position of LDEF in earth orbit, and the position of the earth in relation to other celestial bodies. From this information we can extract essential orbit information.An earlier flight on the Explorer 46 satellite gave first evidence of the existence of submicron-sized particles, mostly associated with fresh meteor streams. We hope to obtain more precise data and estimate lifetimes in interplanetary space.To study the fate and origin of IP (interplanetary) dust, we measure various kinds of time variations. Among the most interesting is the secular variation, i.e., the flux in various meteor streams, as a function of the passage of a comet.One of the challenging problems will be to distinguish IP dust from man-made space debris. The separation will depend on knowing something of the orbits of debris. Probably more important will be the chemical analysis of the particles. The two types of information are in a sense complementary.

SEM studies of fracture phenomena and wall structure in micrometeoroid impact craters in spacecraft metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1332-1333
Author(s):  
L. E. Murr ◽  
C-S. Niou ◽  
J. M. Rivas ◽  
S. Quinones ◽  
A. H. Advani
Keyword(s):  
Crack Nucleation ◽  
Interplanetary Dust ◽  
Impact Craters ◽  
Orbital Debris ◽  
Dust Particles ◽  
Wall Structure ◽  
Considerable Effort ◽  
Interplanetary Dust Particles ◽  
Long Duration ◽  
Target Metal

There has been a considerable effort over nearly a decade to examine the size frequencies, compositions, and origins of particles producing impact craters in a variety of materials surfaces on the Solar Maximum Mission spacecraft, retrieved communications satellites (such as Palapa-B2), and more recently the LDEF (Long Duration Exposure Facility) spacecraft. Three regimes of particles have emerged: natural cosmic dust or interplanetary dust particles (IDP's), man-made orbital debris (including paint or other spacecraft component or coating chips having compositions different from the impacted materials); and orbital debris, often spacecraft debris or secondary (ejecta) debris, having the same composition as the impacted material. However more than 50% of all LDEF impacts into metallic targets did not yield sufficient projectile residue to permit analysis using EDS techniques in electron beam instruments (SEM or STEM in particular).There have been very few attempts to investigate the microstructural and microchemical nature of the micrometeoroid crater walls, especially in the context of the integrity of the wall in relation to the target metal, and the propensity for cracking and crack nucleation within the crater wall.

scholarly journals Measurements of the Elemental and Isotopic Composition of Interplanetary Dust Collected on LDEF

1985 ◽  
Vol 85 ◽  
pp. 121-126
Author(s):  
H. Fechtig ◽  
F. Hörz ◽  
E. Igenbergs ◽  
E. Jessberger ◽  
H. Kuczera ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Isotopic Composition ◽  
Secondary Ion Mass Spectrometry ◽  
Interplanetary Dust ◽  
Simulation Experiments ◽  
Dust Collection ◽  
Impact Simulation ◽  
Long Duration ◽  
Elemental Analyses ◽  
Secondary Ion

AbstractA passive interplanetary dust collection experiment, currently in orbit aboard LDEF (Long Duration Exposure Facility), is described. The collectors, germanium target plates covered by metallized Mylar foils, are designed for secondary ion mass spectrometry (SIMS) measurements of the elemental and isotopic compositions of residues resulting from micrometeoroid (> 10−10 grams) impacts. Impact simulation experiments have demonstrated the validity of the collection concept. Quantitative elemental analyses are complicated by the non-uniform distribution of projectile-derived elements.

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

Relation Between Level of Prefrontal Activity and Subject's Performance

1999 ◽  
Vol 13 (2) ◽  
pp. 117-125 ◽  
Author(s):  
Laurence Casini ◽  
Françoise Macar ◽  
Marie-Hélène Giard
Keyword(s):  
Brain Activity ◽  
Sensory Information ◽  
Practice Phase ◽  
Trained Subjects ◽  
Anagram Task ◽  
Economic Information ◽  
Long Duration ◽  
Level Of Activity ◽  
The Brain ◽  
Processing Mechanism

Abstract The experiment reported here was aimed at determining whether the level of brain activity can be related to performance in trained subjects. Two tasks were compared: a temporal and a linguistic task. An array of four letters appeared on a screen. In the temporal task, subjects had to decide whether the letters remained on the screen for a short or a long duration as learned in a practice phase. In the linguistic task, they had to determine whether the four letters could form a word or not (anagram task). These tasks allowed us to compare the level of brain activity obtained in correct and incorrect responses. The current density measures recorded over prefrontal areas showed a relationship between the performance and the level of activity in the temporal task only. The level of activity obtained with correct responses was lower than that obtained with incorrect responses. This suggests that a good temporal performance could be the result of an efficacious, but economic, information-processing mechanism in the brain. In addition, the absence of this relation in the anagram task results in the question of whether this relation is specific to the processing of sensory information only.

Effects of Fatigue on Cognitive Performance in Long-Duration Simulated Flight Missions

2020 ◽  
Vol 10 (2) ◽  
pp. 82-93
Author(s):  
Eduardo Rosa ◽  
Ola Eiken ◽  
Mikael Grönkvist ◽  
Roger Kölegård ◽  
Nicklas Dahlström ◽  
...  
Keyword(s):  
Executive Functions ◽  
Task Performance ◽  
Cognitive Performance ◽  
Cognitive Tasks ◽  
Fatigue Index ◽  
Fighter Aircraft ◽  
Long Duration ◽  
Metacognitive Accuracy

Abstract. Fighter pilots may be exposed to extended flight missions. Consequently, there is increasing concern about fatigue. We investigated the effects of fatigue and cognitive performance in a simulated 11-hr mission in the 39 Gripen fighter aircraft. Five cognitive tasks were used to assess cognitive performance. Fatigue was measured with the Samn–Perelli Fatigue Index. Results showed that performance in the non-executive task degraded after approximately 7 hr. Fatigue ratings showed a matching trend to the performance in this task. Performance in tasks taxing executive functions did not decline. We interpreted that fatigue can be overridden by increased attentional effort for executive tasks but not for non-executive components of cognition. Participants underestimated their performance and metacognitive accuracy was not influenced by fatigue.

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