The Atmosphere-Space Interactions Monitor (ASIM) is an instrument suite on the International Space Station (ISS) for measurements of lightning, Transient Luminous Events (TLEs) and Terrestrial ...Gamma-ray Flashes (TGFs). Developed in the framework of the European Space Agency (ESA), it was launched April 2, 2018 on the SpaceX CRS-14 flight to the ISS. ASIM was mounted on an external platform of ESA’s Columbus module eleven days later and is planned to take measurements during minimum 3 years. The instruments are an x- and gamma-ray monitor measuring photons from 15 keV to 20 MeV, and an array of three photometers and two cameras measuring in bands at: 180–250 nm, 337 nm and 777.4 nm. Additional objectives that can be addressed with the instruments relate to space physics like aurorae and meteors, and to Earth observation such as dust- and aerosol effects on cloud electrification. The paper describes the scientific objectives of the ASIM mission, the instruments, the mission architecture and the international collaboration supported by the ASIM Science Data Centre. ASIM is the first space mission with a comprehensive suite of instruments designed to measure TLEs and TGFs. Two companion papers describe the instruments in more detail (Østgaard et al. in Space Sci. Rev.,
2019
; Chanrion et al. in Space Sci. Rev.,
2019
).
The Modular Multispectral Imaging Array (MMIA) is a suite of optical sensors mounted on an external platform of the European Space Agency’s Columbus Module on the International Space Station. The ...MMIA, together with the Modular X- and Gamma- ray Sensor (MXGS), are the two main instruments forming the Atmosphere-Space Interactions Monitor (ASIM). The primary scientific objectives of the ASIM mission are to study thunderstorm electrical activity such as lightning, Transient Luminous Emissions (TLEs) and Terrestrial Gamma-ray Flashes (TGFs) by observing the associated emissions in the UV, near-infrared, x- and gamma-ray spectral bands. The MMIA includes two cameras imaging in 337 nm and 777.4 nm, at up to 12 frames per second, and three high-speed photometers at 180–230 nm, 337 nm and 777.4 nm, sampling at rates up to 100 kHz. The paper describes the MMIA and the aspects that make it an essential tool for the study of thunderstorms. The mission architecture is described in Neubert et al. (Space Sci. Rev. 215:26,
2019
, this issue) and the MXGS instruments in Østgaard et al. (Space Sci. Rev. 215:23,
2019
, this issue).
A space
X is called
selectively separable (
R-separable) if for every sequence of dense subspaces
(
D
n
:
n
∈
ω
)
one can pick finite (respectively, one-point) subsets
F
n
⊂
D
n
such that
⋃
n
∈
ω
F
n
...is dense in
X. These properties are much stronger than separability, but are equivalent to it in the presence of certain convergence properties. For example, we show that every Hausdorff separable radial space is R-separable and note that neither separable sequential nor separable Whyburn spaces have to be selectively separable. A space is called
d-separable if it has a dense
σ-discrete subspace. We call a space
X D-separable if for every sequence of dense subspaces
(
D
n
:
n
∈
ω
)
one can pick discrete subsets
F
n
⊂
D
n
such that
⋃
n
∈
ω
F
n
is dense in
X. Although
d-separable spaces are often also
D-separable (this is the case, for example, with linearly ordered
d-separable or stratifiable spaces), we offer three examples of countable non-
D-separable spaces. It is known that d-separability is preserved by arbitrary products, and that for every
X, the power
X
d
(
X
)
is d-separable. We show that D-separability is not preserved even by finite products, and that for every infinite
X, the power
X
2
d
(
X
)
is not D-separable. However, for every
X there is a
Y such that
X
×
Y
is D-separable. Finally, we discuss selective and D-separability in the presence of maximality. For example, we show that (assuming
d
=
c
) there exists a maximal regular countable selectively separable space, and that (in ZFC) every maximal countable space is D-separable (while some of those are not selectively separable). However, no maximal space satisfies the natural game-theoretic strengthening of D-separability.
In Space Enterprise - Living and Working Offworld, Dr Philip Harris provides the vision and rationale as to why humanity is leaving its cradle, Earth, to use space resources, as well as pursuing ...lunar industrialization and establishing offworld settlements. As a management/space psychologist, Dr. Harris presents a behavioral science perspective on space exploration and enterprise. In this his 45thbook, Phil has completely revised and updated the two previous editions of this classic, placing new emphasis on the need for more synergy and participation by the private sector. He not only provides a critical review of what is happening in the global space community, but offers specific strategies for lunar economic development. The author analyzes the human factors in contemporary and future space developments, especially relative to the deployment of people aloft. This user-friendly volume offers numerous photographs, diagrams, exhibits, and case studies.
On bounded sets in Ck(X) Ferrando, Juan Carlos
Topology and its applications,
03/2024, Letnik:
344
Journal Article
Recenzirano
Odprti dostop
In this note we study some topological properties of the bounded sets of the locally convex space Ck(X) of all real-valued continuous functions defined on a Tychonoff space X equipped with the ...compact-open topology as well as of the bounded sets of a (DF)-space. We show that, assuming X is a Lindelöf Čech-complete space, if X is scattered then each bounded set in Ck(X) is a Fréchet-Urysohn space under the weak topology. In the opposite direction, if X is pseudocompact and each bounded set in Ck(X) is Fréchet-Urysohn under the weak topology, then X is k-scattered. We also derive a new condition, related to the closed bounded sets, for a (DF)-space to be quasibarrelled, which we apply to the bounded sets of Ck(X). Finally, we get a sort of Krein-like theorem for Ck(X) when X is a Lindelöf Σ-space.
A raíz del giro espacial, las categorías y metáforas para pensar la espacialidad, --a mayoría de ellas provenientes de la geografía humana-, han sido objeto de notable interés por parte de académicos ...de las ciencias humanas y sociales. La escala, es una de las materias y conceptos fundamentales que constituyen a la geografía humana. La escala ofrece un léxico y una realidad discursiva compleja, porosa, y poderosa que conduce a que la escala no pueda ser tratada solamente como una dimensión de la espacialidad (Jonas, 1994). El debate sobre escala se ha dado principalmente en el mundo anglosajón, de ahí que, algunas de las problemáticas asociadas a la cuestión escalar, estén elaboradas desde encuadres analíticos que van desde el marxismo hasta la ontología plana. En el primero, se encuentra el trabajo pionero de Neil Smith, quien planteó que la escala surge con la producción del espacio en el capitalismo y de las discontinuas y contradictorias características del capital (Smith, 2020). A partir de estas nociones materialistas de la escala surgieron toda una serie de trabajos en la década de los noventa cuyo propósito central consistió en argumentar, a partir de diferentes conceptualizaciones y metáforas que la escala es una construcción social (Marston, 2000).
The Modular X- and Gamma-ray Sensor (MXGS) is an imaging and spectral X- and Gamma-ray instrument mounted on the starboard side of the Columbus module on the International Space Station. Together ...with the Modular Multi-Spectral Imaging Assembly (MMIA) (Chanrion et al.
this issue
) MXGS constitutes the instruments of the Atmosphere-Space Interactions Monitor (ASIM) (Neubert et al.
this issue
). The main objectives of MXGS are to image and measure the spectrum of X- and
γ
-rays from lightning discharges, known as Terrestrial Gamma-ray Flashes (TGFs), and for MMIA to image and perform high speed photometry of Transient Luminous Events (TLEs) and lightning discharges. With these two instruments specifically designed to explore the relation between electrical discharges, TLEs and TGFs, ASIM is the first mission of its kind. With an imaging system and a large detector area MXGS will, for the first time, allow estimation of the location of the source region and characterization of the energy spectrum of individual events. The sensors have fast readout electronics to minimize pileup effects, giving high time resolution of photon detection for comparison with measurements on μs-time scales of lightning processes measured by the MMIA and other sensors in space or on the ground. The detectors cover the large energy range of the relevant photon energies. In this paper we describe the scientific objectives, design, performance, imaging capabilities and operational modes of the MXGS instrument.
A New Study on Tri-Lindelöf Spaces Qoqazeh, Hamza; Atoom, Ali A.; Jaradat, Ali ...
WSEAS Transactions Mathematics,
11/2023, Letnik:
22
Journal Article
Odprti dostop
This paper defines new covering properties in tri-topological spaces called tri-Lindelöf space and the properties of this topological property and its relationship with some other types of ...tri-topological spaces will be studied. The effect of some types of functions on tri-Lindelöf spaces will be studied. This paper also investigates the necessary conditions through which the tri-topological space is reduced into a single topological space. Many and varied illustrative examples will be discussed and many well-known facts and theorems are generalized concerning Lindelöf spaces.
A Hausdorff topological space X is called superconnected (resp. coregular) if for any nonempty open sets U1,…Un⊆X, the intersection of their closures U‾1∩…∩U‾n is not empty (resp. the complement ...X∖(U‾1∩…∩U‾n) is a regular topological space). A canonical example of a coregular superconnected space is the projective space QP∞ of the topological vector space Q<ω={(xn)n∈ω∈Qω:|{n∈ω:xn≠0}|<ω} over the field of rationals Q. The space QP∞ is the quotient space of Q<ω∖{0}ω by the equivalence relation x∼y iff Q⋅x=Q⋅y.
We prove that every countable second-countable coregular space is homeomorphic to a subspace of QP∞, and a topological space X is homeomorphic to QP∞ if and only if X is countable, second-countable, and admits a decreasing sequence of closed sets (Xn)n∈ω such that (i) X0=X, ⋂n∈ωXn=∅, (ii) for every n∈ω and a nonempty relatively open set U⊆Xn the closure U‾ contains some set Xm, and (iii) for every n∈ω the complement X∖Xn is a regular topological space. Using this topological characterization of QP∞ we find topological copies of the space QP∞ among quotient spaces, orbit spaces of group actions, and projective spaces of topological vector spaces over countable topological fields.
The International Space Station (ISS) is the largest man-made structure to orbit Earth and has been conducting research for close to a decade and a half. Yet it is only the latest in a long line of ...space stations and laboratories that have flown in orbit since the early 1970s. The histories of these earlier programs have been all but forgotten as the public focused on other, higher-profile adventures such as the Apollo moon landings.A vast trove of stories filled with excitement, danger, humor, sadness, failure, and success,Outposts on the Frontierreveals how the Soviets and the Americans combined strengths to build space stations over the past fifty years. At the heart of these scientific advances are people of both greatness and modesty. Jay Chladek documents the historical tapestry of the people, the early attempts at space station programs, and how astronauts and engineers have contributed to and shaped the ISS in surprising ways.Outposts on the Frontierdelves into the intriguing stories behind the USAF Manned Orbiting Laboratory, the Almaz and Salyut programs,Skylab, the Apollo-Soyuz Test Project, Spacelab,Mirstation, Spacehab, and the ISS and gives past-due attention to Vladimir Chelomei, the Russian designer whose influence in space station development is as significant as Sergei Korolev's in rocketry.Outposts on the Frontieris an informative and dynamic history of humankind's first outposts on the frontier of space.
PDF
