AIR MEETS SPACE: SHAPING THE FUTURE OF COMMERCIAL SPACE TRAFFIC: I. STUDY INTRODUCTION AND INITIAL RESULTS

There are high expectations for a globally growing market of commercial space travel which is likely to turn in the next 10 to 20 years into a multi-billion Euro business. Those growth expectations are also backed up by OneWeb’s order of about 700 small satellites which are likely to be brought into LEO via air launches and by a continuously growing LEO launch rate showing an increase of about 60% in the last decade. Advances in electric propulsion and spacecraft design (CubeSats) helped to significantly reduce launch costs, so that space exploitation becomes affordable for the first time also to the private sector (e.g., for school labs, micro gravity research or in the area of human spaceflight). Several key players in space business, companies like Blue Origin, Virgin Galactic, XCOR, Orbital or SNC get ready to serve the commercial manned and unmanned spaceflight market by developing their own ballistic reusable space vehicles which shall carry humans and cargo payload into suborbital and LEO space. Europe’s single stage to orbit concepts, like REL’s Skylon or Airbus’ Spaceplane, even target for commercial manned point to point mass transportation, similar to today’s travel through airspace, but with much shorter flight times. All these developments will likely stimulate demands for launch sites and spaceports, where commercial aviation and space vehicles will have to be safely managed and controlled in parallel granting easy access to potential customers. Today, management of and access to commercial aerospace is lacking a coordinated European and global approach so that the expected growing number of space vehicles passing through the air-space interface in a rather “uncontrolled” way will likely pose significant threats to human health and airspace safety. This issue is further intensified by the flood of CubeSats and Unmanned Aerial Vehicles which increase collision risks in LEO and lower airspace. Without doubt, space and airspace will move closer together in the next decade, which is why Space Tra ffi c Management is expected to become a global undertaking. Because we think that safety in aerospace should not be jeopardised by those developments, we initiated an evaluation study together with ESA aiming at the generation of a roadmap towards a European Space Traffic Management. This is the first in a series of papers which gives an outline of the study and presents initial results from a European perspective

Chandra ACIS Survey of M33 (ChASeM33): The enigmatic X-ray emission from IC131

We present the first X-ray analysis of the diffuse hot ionized gas and the point sources in IC131, after NGC604 the second most X-ray luminous giant HII region in M33. The X-ray emission is detected only in the south eastern part of IC131 (named IC131-se) and is limited to an elliptical region of ~200pc in extent. This region appears to be confined towards the west by a hemispherical shell of warm ionized gas and only fills about half that volume. Although the corresponding X-ray spectrum has 1215 counts, it cannot conclusively be told whether the extended X-ray emission is thermal, non-thermal, or a combination of both. A thermal plasma model of kT_e=4.3keV or a single power law of Gamma=2.1 fit the spectrum equally well. If the spectrum is purely thermal (non-thermal), the total unabsorbed X-ray luminosity in the 0.35-8keV energy band amounts to L_X = 6.8(8.7)x10^35erg/s. Among other known HII regions IC131-se seems to be extreme regarding the combination of its large extent of the X-ray plasma, the lack of massive O stars, its unusually high electron temperature (if thermal), and the large fraction of L_X emitted above 2keV (~40-53%). A thermal plasma of ~4keV poses serious challenges to theoretical models, as it is not clear how high electron temperatures can be produced in HII regions in view of mass-proportional and collisionless heating. If the gas is non-thermal or has non-thermal contributions, synchrotron emission would clearly dominate over inverse Compton emission. It is not clear if the same mechanisms which create non-thermal X-rays or accelerate CRs in SNRs can be applied to much larger scales of 200pc. In both cases the existing theoretical models for giant HII regions and superbubbles do not explain the hardness and extent of the X-ray emission in IC131-se.Comment: 28 pages, 7 figures and 2 tables. Accepted for publication in ApJ. For a high resolution version of the paper see http://hea-www.harvard.edu/vlp_m33_public/publications.htm

Detection of the second eclipsing high mass X-ray binary in M 33

Chandra data of the X-ray source [PMH2004] 47 were obtained in the ACIS Survey of M 33 (ChASeM33) in 2006. During one of the observations, the source varied from a high state to a low state and back, in two other observations it varied from a low state to respectively intermediate states. These transitions are interpreted as eclipse ingress and egresses of a compact object in a high mass X-ray binary system. The phase of mid eclipse is given by HJD 2453997.476+-0.006, the eclipse half angle is 30.6+-1.2 degree. Adding XMM-Newton observations of [PMH2004] 47 in 2001 we determine the binary period to be 1.732479+-0.000027 d. This period is also consistent with ROSAT HRI observations of the source in 1994. No short term periodicity compatible with a rotation period of the compact object is detected. There are indications for a long term variability similar to that detected for Her X-1. During the high state the spectrum of the source is hard (power law spectrum with photon index ~0.85) with an unabsorbed luminosity of 2E37 erg/cm2/s (0.2-4.5 keV). We identify as an optical counterpart a V ~ 21.0mag star with T_eff > 19000 K, log(g) > 2.5. CFHT optical light curves for this star show an ellipsoidal variation with the same period as the X-ray light curve. The optical light curve together with the X-ray eclipse can be modeled by a compact object with a mass consistent with a neutron star or a black hole in a high mass X-ray binary. However, the hard power law X-ray spectrum favors a neutron star as the compact object in this second eclipsing X-ray binary in M 33. Assuming a neutron star with a canonical mass of 1.4 M_sun and the best fit companion temperature of 33000 K, a system inclination i = 72 degree and a companion mass of 10.9 M_sun are implied.Comment: 19 pages, 9 figures, ApJ accepte

Observations and modeling of diffuse ionized gas in edge-on galaxies

Die vorliegende Promotionsarbeit beschäftigt sich mit Beobachtungen des Diffusen Ionisierten Gases (DIG) in Edge-on Galaxien und deren Modellierung. Ein im wesentlichen ungeklärter Aspekt ist die Frage nach möglichen Ionisationsmechanismen dieses Gases. Aufgrund von Energieabschätzungen ist die Photoionisation durch junge und heiße O Sterne die wahrscheinlichste Ionisationsquelle. Im Rahmen dieser Arbeit wurden spektroskopische Linienverhältnisse erstellt und mit Vorhersagen gängiger Photoionisationsmodelle verglichen. Da diese Modelle die Beobachtungsbefunde nicht konsistent erklären können, wurde ein neues Photoionisationsmodell entwickelt, das auf Monte Carlo Techniken basiert, den Strahlungstransport exakt berechnet und eine realistischere Geometrie annimmt. Erste Modellrechnungen der Ionisationsstruktur des DIG zeigen ermutigende Ergebnisse. Zur detaillierten Simulation einzelner Galaxien bedarf es jedoch einer eingehenden Erforschung des freien Parameterraumes.The present PhD theses deals with observations of diffuse ionized gas (DIG) in edge-on galaxies and their corresponding modeling. A still unexplained issue concerns possible ionization mechanisms of the DIG. Based upon energy estimations photoionization by young O stars appears to be the most likely ionizing source. Within the scope of this work, spectroscopic line ratios have been obtained which are compared to predictions of common photoionization models. As these codes cannot explain the observational data consistently, a new photoionization model code has been developed which is based on Monte Carlo techniques and assumes a more realistic geometry. First model iterations of the ionization structure of the DIG reveal encouraging results. In order to simulate individual galaxies in detail, a comprehensive investigation of the free prameter space is required

Towards a European Space Traffic Management System

We summarize the main results from an evaluation study which we conducted on behalf of ESA with the aim to identify key pillars for a European Space Traffic Management (STM) system. Our primary focus is on suborbital space transportation, specifically on point-to-point (p2p) connections for human space travel/cargo transportation (including vertical ballistic joyrides), on satellite deployment via air launch systems and on the safe integration of spacecraft with an evolving Air Traffic Management (ATM) system. A Reference Operations Scenario (ROS) is discussed against which the potential European STM system is designed, playing a fundamental role in the ATM and STM integration process. Initial results from simulations of a hypothetical suborbital p2p flight are presented. They indicate that those flights are generally feasible regarding collision risks with traceable space debris/objects. Considering, however, non-traceable space debris/objects, a clear gap between the minimum size of detectable objects and the maximum size of objects against which spacecraft can be shielded becomes obvious. If not properly mitigated, the risk caused by this gap could become a show stopper for commercial suborbital space flights. Finally, the Top 10 list of issues is presented that need to be tackled before a European STM system is ready for implementation

On the Implementation of a European Space Traffic Management System - II. The Safety and Reliability Strategy

This is the second (Paper II) in a mini series of three papers that summarise the final results from an evaluation study which DLR GfR and its partners conducted on behalf of ESA. The objective of this study was to generate a roadmap for the implementation of a European Space Traffic Management (STM) system within the next two decades under consideration of an evolving Air Traffic Management (ATM) system. In Paper I (Tüllmann et al. 2017a) we demonstrated that collision risks do not prevent suborbital space flights from the very beginning. We provided proof of concept that this kind of travel is generally possible, provided significant advances in heat and collision shielding technologies can be achieved. Potential technical, conceptual and organisational setups in response to Europe’s STM needs were discussed, focussing on technology and infrastructure development, Space Debris, Space Surveillance & Tracking, Space Weather Monitoring and ATM and STM integration. The initial roadmap was presented showing that the European STM system could become operational in the 2030 – 2035 time frame. Finally, the Top 10 STM-related issues were identified that need to be solved on EU and UN level. In Paper II, we now cover the relevant Safety & Reliability (S&R) aspects which should be reflected in a STM concept of operations. In this context relevant contributors to unsafe operations and hazardous events as well as the parties at risk are identified. Safety Management Systems in aviation business are investigated in order to check to what extent their S&R concepts and good-practices are applicable to STM operations. An initial Risk Classification Scheme for STM purposes is presented and has been applied to classify the Space Weather risks identified in Paper I. Initial values for the acceptable levels of safety for spaceplane occupants and for third parties at risk are presented and the hazards originating from re-entering objects and airspace sharing are discussed. Paper II finishes with the outline of the envisaged Space Navigation Service Provider (SNSP) certification process. This mini series of papers is concluded by Paper III (Tüllmann et al. 2017c) in which we provide initial system and S&R requirements, constraints and recommendations that should be considered for a European STM setup

On the Implementation of a European Space Traffic Management System - III. Technical Requirements

This third paper (Paper III) concludes the mini series of papers which presents results from an ESA-funded evaluation study that has been collected by DLR GfR and its partner institutes and companies. The objective of this study is to generate a roadmap for the implementation of a European STM system within the next two decades under consideration of an evolving Air Traffic Management (ATM) system. In Paper I (Tüllmann et al. 2017a), we introduced the implementation approach by focussing on the commercial Space Travel market which is expected to develop into a multi-billion Euro business in the coming years and could become a major driver for STM in general. We provided proof of concept that this suborbital space travel is generally possible, given that significant advances in heat and collision shielding technologies can be achieved. The envisioned technical, conceptual and organisational setups were discussed regarding Space Debris, Space Surveillance & Tracking, Space Weather Monitoring, Flight Planning and Scheduling and ATM and STM integration. This work is supplemented by Paper II (Tüllmann et al. 2017b), which discussed Safety & Reliability (S&R) aspects that should be reflected in a S&R concept for the STM system. In this context relevant Safety Management Systems in aviation business were investigated to check to what extent their S&R concepts and good-practices are applicable to STM operations. A first Risk Classification Scheme was presented and initial values for the acceptable levels of safety for the identified hazards were presented and an outline of the envisaged Space Navigation Service Provider (SNSP) certification process was given. In this present work (Paper III) we focus on deriving initial technical high-level requirements and recommendations for a European contribution to Space Traffic Management and define relevant interfaces in the global context. The proposed requirements and interfaces presented here are neither complete nor final and are meant to provide a first rough guidance for space agencies, manufacturers or policy makers and shall stimulate discussions on how a European STM system could be realised

On the Implementation of a European Space Traffic Management System - I. A White Paper

There are high expectations for a global commercial space travel market which is expected to turn into a multi-billion Euro business in the next two decades. Several key players in the space business, companies like Virgin Galactic, SpaceX, Blue Origin or SNC are preparing to serve this market by developing their own ballistic reusable space vehicles to carry humans and cargo payloads into suborbital and Low Earth Orbit (LEO) space. Europe’s single stage to orbit concepts, e.g., REL’s Skylon or Airbus’ Spaceplane, go even further and target for manned suborbital point-to-point (p2p) transportation, similar to today’s travel through airspace, but with much shorter flight times. All these developments will likely stimulate demands for new infrastructure (e.g., for spaceports, tracking & surveillance networks or control centres), requiring the implementation of adequate Space Traffic Management (STM) systems, proper Safety, Reliability and Operations Concepts and a seamless integration of space vehicles into the daily air traffic flow. Despite some initial efforts, management of and access to commercial aerospace is lacking a coordinated approach in Europe and compared to the U.S., Europe is by no means prepared to serve the developing space travel market in the near future. Without a consolidated European, yet global, commitment to commercial STM, the growing number of space vehicles expected to pass through aerospace in the coming years is going to jeopardise human health and airspace safety. In this White Paper (Paper I) we summarise key results from an evaluation study conducted by DLR GfR and partners on behalf of ESA with the objective to generate a roadmap for the implementation of a European STM system within the next two decades under consideration of an evolving Air Traffic Management (ATM) system. In order to demonstrate that collision risks do not prevent suborbital space flights right from the start, we provide proof of concept that this kind of travel is generally feasible, given that significant advances in heat and collision shielding technologies are made. We discuss the envisioned technical, conceptual and organisational setups in response to Europe’s STM needs, focussing on technology and infrastructure development, Space Debris, Space Surveillance & Tracking, Space Weather Monitoring and ATM and STM integration. For the STM system to be operational in the 2030 – 2035 time frame, the initial roadmap is presented together with the Top 10 list of STM issues that need to be tackled. In Paper II (Tüllmann et al. 2017b), we discuss Safety & Reliability aspects related to STM and propose a first risk quantification scheme together with initial values for the acceptable levels of safety of the identified hazards and risks. This mini series of papers is concluded by Paper III (Tüllmann et al. 2017c) in which we provide initial system requirements, constraints and recommendations that should be considered for a European STM setup