Starting with nearby galaxy clusters like Virgo and Coma, and continuing out to the furthest galaxy clusters for which ISO
results have yet been published (z = 0.56), we discuss the development of knowledge of the infrared and associated physical properties of galaxy clusters from
early IRAS observations, through the “ISO-era” to the present, in order to explore the status of ISO's contribution to this
field. Relevant IRAS and ISO programmes are reviewed, addressing both the cluster galaxies and the still-very-limited evidence
for an infrared-emitting intra-cluster medium.
ISO made important advances in knowledge of both nearby and distant galaxy clusters, such as the discovery of a major cold
dust component in Virgo and Coma cluster galaxies, the elaboration of the correlation between dust emission and Hubble-type,
and the detection of numerous Luminous Infrared Galaxies (LIRGs) in several distant clusters. These and consequent achievements
are underlined and described.
We recall that, due to observing time constraints, ISO's coverage of higher-redshift galaxy clusters to the depths required
to detect and study statistically significant samples of cluster galaxies over a range of morphological types could not be
comprehensive and systematic, and such systematic coverage of distant clusters will be an important achievement of the Spitzer
Observatory.
Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries:
France, Germany, the Netherlands, and the United Kingdom) and with the participation of ISAS and NASA. 相似文献
In May of 2011, NASA selected the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) asteroid sample return mission as the third mission in the New Frontiers program. The other two New Frontiers missions are New Horizons, which explored Pluto during a flyby in July 2015 and is on its way for a flyby of Kuiper Belt object 2014 MU69 on January 1, 2019, and Juno, an orbiting mission that is studying the origin, evolution, and internal structure of Jupiter. The spacecraft departed for near-Earth asteroid (101955) Bennu aboard an United Launch Alliance Atlas V 411 evolved expendable launch vehicle at 7:05 p.m. EDT on September 8, 2016, on a seven-year journey to return samples from Bennu. The spacecraft is on an outbound-cruise trajectory that will result in a rendezvous with Bennu in November 2018. The science instruments on the spacecraft will survey Bennu to measure its physical, geological, and chemical properties, and the team will use these data to select a site on the surface to collect at least 60 g of asteroid regolith. The team will also analyze the remote-sensing data to perform a detailed study of the sample site for context, assess Bennu’s resource potential, refine estimates of its impact probability with Earth, and provide ground-truth data for the extensive astronomical data set collected on this asteroid. The spacecraft will leave Bennu in 2021 and return the sample to the Utah Test and Training Range (UTTR) on September 24, 2023.
Small changes in extended winter (November–March) 500 hPa vorticity area index (VAI) values for the 60–80°N latitude band are shown to be positively correlated with changes in a proxy for the high latitude ionosphere-to-surface current density Jz. 相似文献
The construction of a binary timing sequence based on interleaving shorter pseudorandom sequences is proposed and the parameter values giving the minimum acquisition time are found. A comparison is made between the interleaving concept and a previously known scheme. 相似文献
The electrical power systems of orbiting unmanned spacecraft generally consist of energy-conversion devices in combination with energy-storage and conditioning components. The development of efficient pulse-duration modulation regulators suggests configurations smaller, lighter, and cheaper than conventional dissipative voltage regulators. These savings may or may not be realizable, depending upon the system reliability design goal and amount of redundancy required to meet the goal. Three spacecraft electrical power systems, each containing a solar-cell energy converter and using different voltage regulation schemes, are compared for a common mission specification. Each system is made to meet a given reliability goal by a technique that adds redundant components in a manner that minimizes a system design characteristic such as weight. The reliability design goal is kept constant as mission length is increased, permitting system comparison in terms of weight and cost as a function of time. 相似文献