The Case For Renewed Human Exploration Of The Moon

The European Space Agency, ESA, is currently studying 3 high-energy astronomy missions that use the International Space Station (ISS). These are Lobster-ISS, an all-sky imaging X-ray monitor, the Extreme Universe Space Observatory (EUSO) which will study the highest energy cosmic rays by using the Earth's atmosphere as a giant detector and XEUS — the X-ray Evolving Universe Spectroscopy Mission, a potential successor to ESA's XMM-Newton X-ray observatory. These first 2 missions will he attached to the external platforms on the Columbus module, while XEUS will visit the ISS to attach additional X-ray mirrors to enlarge the original 4.5 m diameter mirrors to the 10 m diameter required to observed redshifted iron lines from massive black holes in the early Universe. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effect of the prompt particle environment at L2 on optical CCDs for astronomy and astrophysics

The increasing number of probes carrying large focal planes consisting of many charge-coupled devices (CCDs), planned to be sent to the L2 Lagrangian point, 1.5 million kilometres from Earth in the next 15 years, implies that a detailed study of the effects of the prompt particle environment at L2 on CCDs is required. The focus of this study will be on CCDs for optical astronomy, astrometry and photometric applications. This study will be of particular interest to GAIA the European Space Agency's (ESA) cornerstone optical astronomy mission to further explore and map sections of our galaxy in greater detail. The results will also have implications for future X-ray astronomy missions like the X-ray Evolving Universe Spectroscopy Mission (XEUS). Both the above missions will require large area focal planes incorporating many CCD detectors.The sources of the instrument background are both solar and galactic and if a probe is launched around the peak in the next solar cycle (2010), the possible false detection rate or the amount of data that could be lost during a mission must be determined. This paper presents measured data for a spacecraft in a geostationary orbit, specifically Geosynchronous Operational Environmental Satellites (GOES) data, and makes predictions of the flux and energy of the particle environment at L2. The solar and galactic cosmic ray background was determined by using the Cosmic Ray Effects on Micro-Electronics or CREME96 code. A comparison was then made between the GOES data and the output from the CREME96 code in order to make predictions about the L2 environment.     

XEUS: the physics of the hot evolving universe

This paper describes the next generation X-ray observatory XEUS which has been submitted to the European Space Agency in the framework of the Cosmic Vision 2015–2025 competition and has been selected for an assessment study. The paper summarizes the scientific goals and instrumental concepts of the proposed X-ray telescope with 5 m² effective area and angular resolution better than 5 arc sec.     

All-sky ultraviolet surveys: the needs and the means

This is a crucial time in the history of astronomy with major all-sky surveying work being carried out in all spectral bands, as well as in astrometry. The results of this activity are advancing all fields of astrophysical research, from the investigation of exo-planetary systems to the study of the chemical evolution of the Universe. Full sky surveys are available from the radio domain to X-ray wavelengths but not in the ultraviolet range (UV). While large UV missions are currently under discussion within the astrophysical community and at the major Space Agencies, the efficient use of resources requires preparatory work that can fill the UV surveying gap. This article summarizes the research and on-going activities in this field.     

Investigating Clusters of Galaxies with Planck and Herschel

With the Planck and Herschel satellite missions of the European Space Agency, the far-infrared and submillimeter window will offer new investigation tools toward clusters of galaxies in the distant Universe. These are the Sunyaev Zel'dovich (SZ) effect of the cosmic microwave background and the thermal emission of dust grains. The power of the SZ effect is such that Planckis expected to discover thousands of new clusters at redshifts larger than 0.2, where only a few tens are known today. The dust can be present at large scale in the intracluster medium, and we show that even at very low abundances it is able to be a major cooling agent for the whole cluster. However the dominating dust emission will be that of the background infrared star forming galaxies. In all cases, the data processing of space borne sensitive submillimeter observations of clusters of galaxies such as the one that Planck and Herschel will provide, will require a very carefull combined analysis of the SZ effect and dust thermal emission.     

Limited By Cost: The Case Against Humans In The Scientific Exploration Of Space

Human space flight represents a heady mix of bravery and drama which can be inspirational to nations and to humankind but at huge economic cost. Due to the current high launch costs only a handful of people have ventured beyond low Earth orbit and walked on the Moon, propelled by aspirations related more to the Cold War than to science. Problems with reusable launch vehicle development mean that severe launch cost limitations will exist for some time. Meanwhile, cheaper robotic probes have visited all the planets except Pluto, flown by comets, landed on Mars, Venus and an asteroid, have probed Jupiter's atmosphere and studied the Universe beyond our own solar system with telescopes. Using these data we are determining mankind's place in the Universe. Public interest in the historic Eros landing eclipsed a simultaneous space walk at the fledgling International Space Station and the Mars Pathfinder landing generated hundreds of millions of website hits in a few days. Given the fact that hundreds of Mars missions could be flown for the still-escalating cost of the International Space Station, the unsuitability of human bodies for deep space exploration, and the advances in 3-d and virtual reality techniques, we discuss whether human exploration needs a place in a realistic, useful and inspirational space programme. This revised version was published online in July 2006 with corrections to the Cover Date.     

Microbial contamination monitoring and control during human space missions

The ubiquity and resilience of microorganisms makes them unavoidable in most environments including space habitats. The impaired immune system of astronauts in flight raises the level of concern about disease risk during human space missions and additionally these biological contaminants may affect life support systems and hardware. In this review, the microbial contamination observed in manned space stations and in particular the International Space Station ISS will be discussed, demonstrating that it is a microbiologically safe working and living habitat. Microbial contamination levels were in general below the implemented quality standards, although, occasional contamination hazard reports indicate that the current prevention and monitoring strategies are the strict minimum.     

The SIMBOL-X hard X-ray mission

SIMBOL-X is a hard X-ray mission based on a formation flight architecture, operating in the 0.5–80 keV energy range, which has been selected for a comprehensive Phase A study, being jointly carried out by CNES and ASI. SIMBOL-X makes uses of a long (in the 25–30 m range) focal length multilayer-coated X-ray mirrors to focus for the first time X-rays with energy above 10 keV, resulting in at least a two orders of magnitude improvement in angular resolution and sensitivity compared to non focusing techniques used so far. The SIMBOL-X revolutionary instrumental capabilities will allow us to elucidate outstanding questions in high energy astrophysics, related in particular to the physics and energetic of the accretion processes on-going in the Universe, also performing a census of black holes on all scales, achieved through deep, wide-field surveys of extragalactic fields and of the Galactic center, and the to the acceleration of electrons and hadrons particles to the highest energies. In this paper, the mission science objectives, design, instrumentation and status are reviewed. PACS: 95.55 – Astronomical and space-research instrumentation 95.85 – Astronomical Observations 98.85.Nv – X-ray     

今后几年的月球探测和月球科学

近年来月球探测已经进入了一个全新的时代。特别是 1 990年以来 ,多个月球探测计划已经被成功实现 ,而且另外还有多个探测计划也在准备当中 ,并将在未来的几年内发射升空。在这种背景之下 ,中国的航天机构和有关的科学家也开始积极酝酿和开发自己的月球探测计划。这些月球探测计划将利用卫星上搭载的各种仪器探测和测量月球的地质和地理特性、化学成分和矿物组成、月球物理学特征以及包含地球大气在内的地月空间环境和行星际空间环境 ;进一步研究月球的起源和演化 ,探明月面环境 ,研究太阳等离子体物理 ,提供月面天文台和月面长期科研基地的候选地址 ,调查月球上的可利用资源 ,为将来开发月球提供充实的背景资料。参与新一轮的月球探测同样也为中国天文学研究带来了新的机会。     

Constraining the geometry of the neutron star RX J1856.5−3754

RX J1856.5−3754 is one of the brightest, nearby isolated neutron stars (NSs), and considerable observational resources have been devoted to its study. In previous work, we found that our latest models of a magnetic, hydrogen atmosphere match well the entire spectrum, from X-rays to optical (with best-fitting NS radius   R ≈ 14  km, gravitational redshift   z _g∼ 0.2  , and magnetic field   B ≈ 4 × 10¹²  G). A remaining puzzle is the non-detection of rotational modulation of the X-ray emission, despite extensive searches. The situation changed recently with XMM–Newton observations that uncovered 7-s pulsations at the     level. By comparing the predictions of our model (which includes simple dipolar-like surface distributions of magnetic field and temperature) with the observed brightness variations, we are able to constrain the geometry of RX J1856.5−3754, with one angle <6° and the other angle     , though the solutions are not definitive, given the observational and model uncertainties. These angles indicate a close alignment between the rotation and the magnetic axes or between the rotation axis and the observer. We discuss our results in the context of RX J1856.5−3754 being a normal radio pulsar and a candidate for observation by future X-ray polarization missions such as Constellation-X or XEUS .     

Interferometry with the Large Binocular Telescope

The Large Binocular Telescope (LBT) will be the largest single telescope in the world when it is completed in 2005. The unique structure of the telescope incorporates two, 8.4 meter diameter primary mirrors on a 14.4 meter center-to-center mounting. This configuration provides the equivalent collecting area of a 12 meter telescope, and when combined coherently, the two optical paths offer very interesting possibilities for interferometry. Two initial interferometric instruments are planned for the LBT. A group based at the University of Arizona is constructing LBTI, a pupil-plane, nulling beam combiner operating in the thermal infrared N band. This instrument will search for and measure zodiacal light in candidate stellar systems for the Terrestrial Planet Finder (TPF) and Darwin missions. Expansion ports can accomodate additional instruments. A second group, based in Heidelberg, Arcetri, and Köln, is building LINC-NIRVANA, a near-infrared Fizeau-mode beam combiner. This type of observation preserves phase information and allows true imagery over a wide field of view. Using state-of-the-art detector arrays, coupled with advanced adaptive optics, LINC-NIRVANA will deliver the sensitivity of a 12 m telescope and the spatial resolution of a 23 m telescope, over a field of view up to 2 arc minutes square.     

Using ISS telescopes for electromagnetic follow-up of gravitational wave detections of NS-NS and NS-BH mergers

The International Space Station offers a unique platform for rapid and inexpensive deployment of space telescopes. A scientific opportunity of great potential later this decade is the use of telescopes for the electromagnetic follow-up of ground-based gravitational wave detections of neutron star and black hole mergers. We describe this possibility for OpTIIX, an ISS technology demonstration of a 1.5 m diffraction limited optical telescope assembled in space, and ISS-Lobster, a wide-field imaging X-ray telescope now under study as a potential NASA mission. Both telescopes will be mounted on pointing platforms, allowing rapid positioning to the source of a gravitational wave event. Electromagnetic follow-up rates of several per year appear likely, offering a wealth of complementary science on the mergers of black holes and neutron stars.     

Measuring the power spectrum of density fluctuations at intermediate redshift with X-ray background observations

The precision of intensity measurements of the extragalactic X-ray background (XRB) on an angular scale of about a degree is dominated by spatial fluctuations caused by source confusion noise. X-ray source counts at the flux level responsible for these fluctuations, ∼10⁻¹² erg cm⁻² s⁻¹, will soon be accurately measured by new missions, and it will then be possible to detect the weaker fluctuations caused by the clustering of the fainter, more distant sources which produce the bulk of the XRB. We show here that measurements of these excess fluctuations at the level of (Δ I/I )∼2×10⁻³ are within reach, improving by an order of magnitude on present upper limits. Since it is likely that most (if not all) of the XRB will be resolved into sources by AXAF , subsequent optical identification of these sources will reveal the X-ray volume emissivity in the Universe as a function of redshift. With these ingredients, all-sky observations of the XRB can be used to measure the power spectrum (PS) of the density fluctuations in the Universe at comoving wavevectors k _c∼0.01–0.1 Mpc⁻¹ at redshifts where most of the XRB is likely to originate ( z ∼1–2) with a sensitivity similar to, or better than, the predictions from large-scale structure theories. A relatively simple X-ray experiment, carried out by a large-area proportional counter with a 0.5–2 deg² collimated field of view scanning the whole sky a few times, would be able to determine the PS of the density fluctuations near its expected peak in wavevector with an accuracy better than 10 per cent.     

Design Aspects of Grazing Angle Multilayer Mirrors for Soft γ-Rays

If sensitive enough, future missions for nuclear astrophysics will be a great help in understanding supernovae explosions. In contrast to coded-mask instruments, both crystal diffraction lenses and grazing angle mirrors offer a possibility to construct a sensitive instrument to detect γ-ray lines in supernovae. We report on possible implementations of grazing angle mirrors and simulations carried out to determine their performance.     

Summary of the First NUVA Conference Space Astronomy: the UV Window to the Universe

In this summary of the conference Space Astronomy: the UV Window to the Universe, held in El?Escorial, Spain, May 28 to June 1, 2007, I identify the important scientific questions posed by the speakers and the corresponding discoveries that future ultraviolet space instruments should enable. The science objectives described by the various speakers naturally fall into groups according to the needed instrumental requirements: wavelength coverage, spectral resolution, sensitivity, rapid access to targets, monitoring, and signal/noise. Although most of the science objectives presented during the conference require UV spectra in the 1,170–3,200 Å range, there are important science objectives that require spectra in the 912–1,170 Å range and at shorter wavelengths. I identify the limitations of present instruments for meeting these requirements. To avoid the upcoming UV dark age, important work must be done to properly build the World Space Observatory (WSO) and to plan future space missions.     

Why Study the Sun?

In this presentation we briefly describe the Sun through large number of illustrations and pictures of the Sun taken from early times to the present day space missions. The importance of the study of the Sun is emphasized as it is the nearest star which presents unparallelled views of surface details and numerous phenomena. Our Sun offers a unique celestial laboratory where a large variety of phenomena take place, ranging in temporal domain from a few milliseconds to several decades, in spatial domain from a few hundred kilometers to thousands of kilometers, and in the temperature domain from a few thousand degrees to several million degrees. Its mass motion ranges from thousandths to thousands of kilometers per second. Such an object provides us with a unique laboratory to study the state of matter in the Universe. The existing solar ground-based and space missions have already revealed several mysteries of the outer environment of our Sun and much more is going to come in the near future from planned new sophisticated ground-based solar telescopes and Space missions. The new technique of helioseismology has unravelled many secrets of the solar interior and has put the Standard Solar Model (SSM) on firm footing. The long-standing problem of solar neutrinos has been recently sorted out, and even the ‘back side’ view of the Sun can be seen using the technique of holographic helioseismology.     

Solar System Observations with MIRI, The Mid InfraRed Instrument on the James Webb Space Telescope

MIRI is the Mid InfraRed Instrument for the James Webb Space Telescope (JWST) and will provide imaging, coronography and integral field spectroscopy in the range between 4.9 and 28.6  $\upmu \hbox{m}.$ We summarise solar system observations which may be possible with this instrument, drawing on examples of observations made with previous space missions such as IRAS, ISO and Spitzer.     

Detecting quasars at very high redshift with next generation X-ray telescopes

The next generation of X-ray telescopes have the potential to detect faint quasars at very high redshift and probe the early growth of massive black holes (BHs). We present modelling of the evolution of the optical and X-ray active galactic nucleus (AGN) luminosity function at  2 < z < 6  based on a cold dark matter (CDM) merger-driven model for the triggering of nuclear activity combined with a variety of fading laws. We extrapolate the merger-driven models to   z > 6  for a range of BH growth scenarios. We predict significant numbers of sources at   z ∼ 6  with fluxes just an order of magnitude below the current detection limits and thus detectable with XEUS and Constellation-X , relatively independently of the fading law chosen. The predicted number of sources at even higher redshift depends sensitively on the early growth history of BHs. For passive evolution models in which BHs grow constantly at their Eddington limit, detectable BHs may be rare beyond   z ∼ 10  even with Generation-X . However, in the more probable scenario that BH growth at   z > 6  can be described by passive evolution with a small duty cycle, or by our merger-driven accretion model, then we predict that XEUS and Generation-X will detect significant numbers of BHs out to   z ∼ 10  and perhaps beyond.     

Analysis of the Space Debris Impacts Risk on the International Space Station

Öpik's analytical expressions relate in a simple way the semimajor axis, eccentricity and inclination of the projectile orbit to the magnitude and direction of the relative velocity vector at impact on a given target on circular orbit. These interesting quantities, along with the impact probability of any given projectile, can be all represented on a suitable projection giving a comprehensive picture of the impact risk on the selected target. By means of this theory a complete analysis of the impact risk on the International Space Station (ISS) is performed. It is found that the large majority of the debris population is on orbits such that a correlation exists between their impact velocity on the ISS and the angle between the velocity vector of the impactor and that of the ISS. The impactor population also is separated in terms of nature of the projectiles, with most of the low-medium velocity ones being particles related to solid rocket motor slag condensates. On the other hand, the highest velocity projectiles are composed mainly by fragments of past in-orbit explosions.The flux of projectiles on the ISS has been calculated for the planned operative lifetime of the Station, by assuming a realistic scenario of the future debris environment evolution and the actual planned altitude profile for the ISS mission. There is a factor 2-3 variation of the flux due to the changing ISS altitude. The most dangerous part of the mission appears to be the central one, when the ISS will orbit at about 450 km above the Earth.     

An evaluation of the exposure in nadir observation of the JEM-EUSO mission

We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme Universe Space Observatory, on-board the Japanese Experiment Module of the International Space Station. Designed as a mission to explore the extreme energy Universe from space, JEM-EUSO will monitor the Earth’s nighttime atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by ultra-high energy cosmic rays. In the present work, we discuss the particularities of space-based observation and we compute the annual exposure in nadir observation. The results are based on studies of the expected trigger aperture and observational duty cycle, as well as, on the investigations of the effects of clouds and different types of background light. We show that the annual exposure is about one order of magnitude higher than those of the presently operating ground-based observatories.