EURASTROS ascent trajectory and abort analysis
Creators: name:  K. BERGMANN 
name:   P. MARQUARDT 
name:   I. DIETLEIN 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: HUMAN
SPACEFLIGHT

description: The EURASTROS study [1] was a joined study between Ariane Group GmbH and German Aerospace Center (DLR), exploring the astronautic transport capabilities of Ariane 6. The study included the preliminary design of a crew module (CM) [2], a service module (SM) [3], a performance analysis of possible Launch Abort System (LAS) concepts and a cost analysis [4]. This paper presents the work performed with the purpose to define the general ascent strategy and to design suitable end-to-end abort strategies compatible with the mission and system requirements. It shows the selected reference ascent trajectory and covers detailed preliminary analyses of the exo- and endo-atmospheric abort scenarios regarded within the EURASTROS project. The crew module, envisioned for a total crew of up to three astronauts, was designed with close resemblance to the Apollo CM, with a Service Module (SM) for exo-atmospheric flight at the rear and a Launch Abort System (LAS) for endo-atmospheric abort at the front, but with volume reduced by 28 %. For the LAS design, the most promising configurations were traded and designed towards minimum thrust allowing to reach a minimum safety distance of 200 m to the launch vehicle within less than 3 seconds after separation and to fulfill further safety requirements in case of an abort from launch pad. Simulations conducted at DLR RY-SRT, utilizing an aerodynamic database generated by DLR AS-HYP concluded that the bare minimum thrust has to exceed 950 kN for both concepts. Based on these results and a subsequent mass budget estimation, an abort-tower-configuration with a total mass of about 5300 kg was used as a baseline for the atmospheric LAS. The SM is based on the ASTRIS kick stage and utilizing the engine BERTA running on storable fuel. This module is dimensioned to provide continuous exo-atmospheric launch abort capabilities while preventing any potential impact on populated areas on European and Eurasian soil. For such an abort scenario, the Last Direct Re-entry Point (LDR) after which an abort to orbit would be executed, has been defined. Influences of the corresponding maneuver pitching angles on ballistic downrange as well as on required time for abort to orbit are explored and the SM minimum thrust was adjusted to yield sufficient performance capabilities. Eventually, six abort modes for exo-atmospheric flight are proposed and discussed. All of the above analyses were closely tied to continuous optimization of the A64 ascent trajectory and corresponding performance analyses. Astronautic transport to an ISS orbit was used as reference study case. The conducted analyses explored multiple possibilities for performance adjustment in agreement with human rated mission requirements, while also respecting space debris mitigation standards. Eventually these investigations concluded in the proposal of 11-ton propellant un-loading of the Upper Liquid Propulsion Module (ULPM) with respect to standard GTO upper stage fuel, yielding a trajectory enabling for maximum performance and also sufficient safety. References [1] Ali Gulhan, Marco Wolf, et.al.; An Overview of the EURASTROS Study, EUCASS-3AF CONFERENCE, LILLE, FRANCE, 2022. [2] Pascal Marquardt, Markus Fertig, Thomas Reimer, Ali Gulhan; EURASTROS capsule design and re-entry analysis, EUCASS-3AF CONFERENCE, LILLE, FRANCE, 2022. [3] Alex Plebuch, Pascal Marquart, Marco Wolf; System design of EURASTROS reference configurations and mission, EUCASS-3AF CONFERENCE, LILLE, FRANCE, 2022. [4] Andy Braukhane, Alex Plebuch, Thomas Renk; EURASTROS demonstration plan and cost analysis, EUCASS-3AF CONFERENCE, LILLE, FRANCE, 2022.