phase-A Study Research Articles

Modeling impact outcomes for the Double Asteroid Redirection Test (DART) mission

The Double Asteroid Redirection Test (DART) is a NASA mission concept currently in Phase-A study, which will provide the first full-scale test of a kinetic impactor deflection mission for planetary defense. The DART spacecraft will target the moon of Didymos (Didymos-B, or “Didymoon”) and impact the smaller body at ~6 km/s with ~500 kg mass. The change in orbital period of the moon will then be measured using ground-based observations, which can be used to estimate the momentum enhancement of the moon from the impact. Impact modeling provides a basis for interpretation of the DART impact and observations (including the calculation of the momentum enhancement, β, the period change, and ejecta mass for a given impact scenario). Here, we present results from simulations using the shock physics codes CTH and Spheral of a DART-like impact into an asteroid target. Variations in target composition and porosity are simulated to examine their effect on β. A variety of methods are used to calculate β, and these simulations suggest that β can be calculated using any of them, depending on what type of simulation is performed, and provide consistent results. The results also indicate that varying the target composition (e.g., whether the target is made up of something granite-like or more akin to basalt or pumice) does not significantly affect the results. More significant changes are seen when parameters such as porosity are varied: increased porosity decreases β, alters the crater shape, and increases ∆v. Simulations also suggest that the form of porosity is important: macro-porosity has a significant effect on the cratering process that is different than equivalent micro-porosity.

Ejecta cloud from the AIDA space project kinetic impact on the secondary of a binary asteroid: I. mechanical environment and dynamical model

An understanding of the post-impact dynamics of ejecta clouds are crucial to the planning of a kinetic impact mission to an asteroid, and also has great implications for the history of planetary formation. The purpose of this article is to track the evolution of ejecta produced by AIDA mission, which targets for kinetic impact the secondary of near-Earth binary asteroid (65803) Didymos on 2022, and to feedback essential informations to AIDA’s ongoing phase-A study. We present a detailed dynamic model for the simulation of an ejecta cloud from a binary asteroid that synthesizes all relevant forces based on a previous analysis of the mechanical environment. We apply our method to gain insight into the expected response of Didymos to the AIDA impact, including the subsequent evolution of debris and dust. The crater scaling relations from laboratory experiments are employed to approximate the distributions of ejecta mass and launching speed. The size distribution of fragments is modeled with a power law fitted from observations of real asteroid surface. A full-scale demonstration is simulated using parameters specified by the mission. We report the results of the simulation, which include the computed spread of the ejecta cloud and the recorded history of ejecta accretion and escape. The violent period of the ejecta evolution is found to be short, and is followed by a stage where the remaining ejecta is gradually cleared. Solar radiation pressure proves to be efficient in cleaning dust-size ejecta, and the simulation results after two weeks shows that large debris on polar orbits (perpendicular to the binary orbital plane) has a survival advantage over smaller ejecta and ejecta that keeps to low latitudes.

ADAHELI+: exploring the fast, dynamic Sun in the x-ray, optical, and near-infrared

Advanced Astronomy for Heliophysics Plus (ADAHELI+) is a project concept for a small solar and space weather mission with a budget compatible with an European Space Agency (ESA) S-class mission, including launch, and a fast development cycle. ADAHELI+ was submitted to the European Space Agency by a European-wide consortium of solar physics research institutes in response to the Call for a small mission opportunity for a launch in 2017, of March 9, 2012. The ADAHELI+ project builds on the heritage of the former ADAHELI mission, which had successfully completed its phase-A study under the Italian Space Agency 2007 Small Mission Programme, thus proving the soundness and feasibility of its innovative low-budget design. ADAHELI+ is a solar space mission with two main instruments: ISODY+: an imager, based on Fabry-Perot interferometers, whose design is optimized to the acquisition of highest cadence, long-duration, multiline spec- tropolarimetric images in the visible/near-infrared region of the solar spectrum. XSPO: an x-ray polarimeter for solar flares in x-rays with energies in the 15 to 35 keV range. ADAHELI+ is capable of performing observations that cannot be addressed by other currently planned solar space missions, due to their limited telemetry, or by ground-based facilities, due to the problematic effect of the terrestrial atmosphere.©TheAuthors.PublishedbySPIEunder

Tandem-L: A Highly Innovative Bistatic SAR Mission for Global Observation of Dynamic Processes on the Earth's Surface

Tandem-L is a proposal for a highly innovative L-band SAR satellite mission for the global observation of dynamic processes on the Earth's surface with hitherto unparalleled quality and resolution. It is based on the results of a pre-phase A study which started in 2013 and is currently undergoing a phase-A study. Thanks to the novel imaging techniques and the vast recording capacity with up to 8 terabytes/day, it will provide vital information for solving pressing scientific questions in the biosphere, geosphere, cryosphere, and hydrosphere. By this, the new L-band SAR mission will make an essential contribution for a better understanding of the Earth system and its dynamics. Tandem-L will, moreover, open new opportunities for risk analysis, disaster management and environmental monitoring by employing especially designed acquisition modes and techniques in combination with a reconfigurable tandem satellite configuration and an L-band SAR instrument with advanced digital beamforming techniques.

SSETO—Small Satellite for Exoplanetary Transit Observation

SSETO is the result of a phase-A study in context of the small satellite program of the University of Stuttgart that demonstrates the capability of a university institute to build a small satellite with a budget of 5million Euro. The satellite will be capable of observing exoplanets in a Neptune–Earth scale and obtaining data of interstellar dust. Due to a system failure of NASA׳s Kepler mission, there is currently (October 2013) a lack of satellites searching for exoplanets. This paper details the design of subsystems and payload, as well as the required test tasks in accordance with the mission profile at a conceptional level. The costs for standard spacecraft testing and integration tasks are included, but not those of launch, ground support, operations and engineer working hours.

European small geostationary communications satellites

Hispasat Advanced Generation 1 (HAG1) is the first satellite using the SGEO platform, which is under the development in the ESA Artes-11 program. Since the last presentation in the IAC 2007, a European industrial consortium led by OHB has completed the mission and spacecraft design. The platform Preliminary Design Review has been carried out in May 2008. The customer for the first mission is a commercial operator—Hispasat. The contract was signed in December 2008 and the satellite will be launched in 2012. To give confidence to the customer, SGEO platform will use up to date flight proven technologies. HAG1 carries 20/24 Ku-band and 3/5 Ka-band transponders to provide commercial services. Some innovative payload technologies will also be flown on board of HAG1 to gain in-orbit heritage. SGEO has also been selected as the baseline platform for the ESA Data Relay Satellite (EDRS). Phase-A study has just kicked off in January 2009. The targeted launch date is 2013. Heinrich Hertz will also use the SGEO platform. Heinrich Hertz is funded by the German Space Agency (DLR) and provides flight opportunities for technologies and components developed by the German Space Industry. With the HAG1 contract in hand, and EDRS and Heinrich Hertz in the line, OHB with its partners has the confidence that it will be able to speed up the product development of the SGEO platform for potential customers in the commercial market. This paper will first present the updated platform design and the status of the product development will be followed with the introduction of innovative payload technologies on board the first mission—HAG1 and ended with the mission concepts of EDRS and Heinrich Hertz missions.

Status report of the electric sail in 2009

The electric sail is a new propulsion concept which uses charged tethers to extract momentum from the solar wind by Coulomb interaction. We give a status report of the electric sail as of October 13, 2009. We report progress during the last two years in plasma physical thrust estimation, tether manufacture methods, navigability, test mission planning and applications. The thrust estimates have gone up recently by a factor of about five, samples of final-type tether have been manufactured, accurate navigability of the sail in variable solar wind has been shown numerically, a CubeSat test mission for measuring the electric sail force in orbit is in Phase-A study and trajectory calculations for many classes of missions have been made. Using existing technology, it seems possible to build an electric sail of ∼ 1 N thrust, ∼ 100 kg mass and ∼ 10 year lifetime. In terms of lifetime produced impulse per unit propulsion system mass, such a near-term and general-purpose device would be about 1000 times more efficient than a chemical rocket and about 100 times more efficient than a contemporary ion engine. This level of performance is enough to enable a host of important applications, such as in situ measurements in interstellar space, sample return from most solar system targets, non-Keplerian orbit probes for space weather forecasting and helioseismology and economical utilisation of asteroid resources.

Marco Polo – A Mission to Return a Sample from a Near-Earth Object – Science Requirements and Operational Scenarios

Marco Polo is a mission to return a sample from a Near-Earth Object of primitive type (class C or D). It is foreseen as a collaborative effort between the Japanese Space Agency (JAXA) and the European Space Agency (ESA). Marco Polo is currently in a Phase-A study. This paper focuses on the scientific requirements provided to the industrial study consortia in Europe as well as the possible mission scenario at the target object in order to achieve the overall mission science objectives. The main scientific reasons for going to a Near-Earth Object are to understand the initial conditions and evolution history of the solar nebula, to understand how major events (e.g. agglomeration, heating) influence the history of planetesimals, whether primitive class objects contain presolar material, what the organics were in primitive materials, how organics could shed light on the origin of molecules necessary for life, and what the role of impacts by NEOs would be in the origin and evolution of life on Earth.

JEM-EUSO: Extreme Universe Space Observatory on JEM/ISS

EUSO is a super-wide field UV telescope to detect Ultra-High Energy Cosmic-Rays (UHECRs) with energy above 10 20 eV . It is attached to the International Space Station (ISS) and observes fluorescence photons emitted by giant air showers produced by UHECR. The three dimensional development of the shower is reconstructed from a series of images of the shower. Phase-A study of EUSO under the European Space Agency (ESA) has successfully finished in July 2004. The phase-B study, however, has been postponed for a long time because of financial problems in ESA and Italy. Then, Japanese and U.S. teams re-defined EUSO as a mission attached to the Japanese Experiment Module/Exposure Facility of ISS. They renamed it as JEM-EUSO and started the preparation targeting the launch in 2012 in the framework of second phase of JEM/EF utilization. The outline of the mission is presented.

AO Assisted NIR 3D Spectroscopic Imaging – Can an ELT See the Earth at 10pc?

The European southern observatory ESO is currently undertaking the ambitious task of building a “Planet Finder” instrument for the VLT. The concept for this instrument includes a 3D spectroscopic imager assisted by a very powerful eXtreme AO system. In one of the two phase-A studies for this project, we have developed a simulation software for this kind of instrument which has now been extended and applied to the case of various ELTs. In this presentation, we give results of simulations and discuss achievable signal to noise ratios and prospects for detection and characterization from young gas giants down to terrestrial type planets. ELTs of various diameters are considered as well as a set of environmental conditions.

보현산천문대와 소백산천문대에서의 근적외선 관측 조건

Korea Astronomy Observatory(KAO) has been developing the KAONICS, KAO Near-Infrared Camera System, which will be used for near-infrared observations in the ground-based telescopes of Korea. As a phase-A study for this work, we investigated observational environments at the Sobaeksan Optical Astronomy Observatory(SOAO) and the Bohyunsan Optical Astronomy Observatory(BOAO) quantitatively. In the J, H, K, and L bands, atmospheric transmission was calculated mainly depending on the PWV(Precipitable Water Vapour), and limiting magnitudes were computed for the SOAO and the BOAO, respectively. We conclude that these observatories have similar observing capabilities and domestic observations are possible in near-infrared.

Imaging in Hard X-ray Astronomy

The energy range of hard X-rays is a key waveband to the study of high energy processes in celestial objects, but still remains poorly explored. In contrast to direct imaging methods used in the low energy X-ray and high energy gamma-ray bands, currently imaging in the hard X-ray band is mainly achieved through various modulation techniques. A new inversion technique, the direct demodulation method, has been developed since early 90s. with this technique, wide field and high resolution images can be derived from scanning data of a simple collimated detector. The feasibility of this technique has been confirmed by experiment, balloon-borne observation and analyzing simulated and real astronomical data. Based the development of methodology and instrumentation, a high energy astrophysics mission – Hard X-ray Modulation Telescope (HXMT) has been proposed and selected in China for a four-year Phase-A study. The main scientific objectives are a full-sky hard X-ray (20–200 keV) imaging survey and high signal-to-noise ratio timing studies of high energy sources.

A catalogue of potential landing sites for the INTERMARSNET mission

In the framework of the INTERMARSNET Phase-A Study, work was undertaken to create a new catalogue of potential landing sites on Mars to provide the INTERMARSNET mission with a suitable database consisting of sites satisfying all the specific scientific objectives and requirements and technical constraints of a network mission such as INTERMARSNET. The scientific objectives and requirements derive from network science investigations (seismology, meteorology), which provide results at global and regional scale, and from individual site characterization in terms of geology division, geomorphology, geochemistry, iron and volatile studies, and atmospheric structure, at a local scale. After the scientific requirements were fully addressed, a careful evaluation of the mission constraints arising from technical design and mission analysis requirements was carried out. The constraints considered in the study arose from launch scenario, probe delivery and atmospheric entry, landing site altitude and latitude, site terrain characteristics, data relay orbiter, planetary protection, and from the network configuration requirements for the different mission scenario options. A detailed study of the surface of Mars has revealed a set of 100 potential landing sites, all of them scientifically meaningful and technically feasible. These sites form a catalogue of potential landing sites, allowing to optimize the specific investigations of the martian atmosphere, surface and interior, to be performed by the INTERMARSNET mission. The catalogue has been used as a database for the selection of landing site configurations satisfying the network science requirements. Two options in the mission scenario have been considered in the study, the Single-Probe Carrier (SPC) and the Multi-Probe Carrier (MPC). For each option six landing site configurations, each composed of four landers, a three lander regional network plus one antipodal site, have been selected, that way to fulfil the scientific objectives and to be fully compatible with the targeting and delivery capability of the adopted mission scenario option. Of the six configurations for each option, four are targeted to the Tharsis region and two to the Elysium region. These two regions have been selected to host the regional network because they are the most likely areas on Mars to still undergo tectonic activity. For each option one of the configurations has been selected as the mission baseline. Both baseline configurations, for MPC and SPC, are targeted to the Tharsis region.