Statistical Reliability Analysis of Interplanetary Spacecraft Operating at Different Interplanetary Extremity

Reliability of the spacecraft determines the extent of success probability and mission accomplishment. Despite effective testing and integration, the complexity of the space environment affects reliability. In this paper, we investigate the reliability behaviour of interplanetary spacecraft operating at different interplanetary extremities. So, our investigation assesses spacecraft inhered in interplanetary space with the context of the interplanetary boundary (between distinct planetary orbit or within the bounds of heliopause). From the perspective of spacecraft reliability in interplanetary space, we have excluded planetary landers, atmospheric probes, and satellites maneuvering earth orbit. Thus, we have identified 131 spacecraft (includes 82 probes within the bounds of Sun and the Earth, and 49 within the bounds of Earth and Heliopause) along with their gross mass at launch and lifespan. Based on acquired data, we first conduct a non-parametric analysis of spacecraft reliability to obtain two reliability curves for distinct interplanetary extremity. We then perform a parametric fit (Weibull Distribution) over the data to show the analogy of reliability behaviour. Results showed that the spacecraft operating beyond the extremity of the Earth and the Mars exhibits increased reliability than any other interplanetary extremity. In addition to this, we execute reliability analysis over spacecraft of various mass categories (Small-Medium-Large) to testify the reliability effect interpreted by Dubos in 2010. Finally, we discuss the possible factors and causes accountable for the difference in reliability behaviour concerning the spacecraft design and integration, testing, and constraints in considering spacecraft mass.

Dynamic Biasing for Improved On-Orbit Total-Dose Lifetimes of Commercial Electronic Devices

The survivability of microelectronic devices in ionizing radiation environments drives spacecraft design, capability, mission scope, and cost. This work exploits the periodic nature of many space radiation environments to extend device lifetimes without additional shielding or modifications to the semiconductor architecture. We propose a technique for improving component lifetimes through reduced total-dose accumulation by modulating device bias during periods of intense irradiation. Simulation of this ``dynamic biasing" technique applied to single-transistor devices in a typical low-Earth orbit results in an increase of component life from 114 days to 477 days (318% improvement) at the expense of 5% down time (95% duty cycle). The biasing technique is also experimentally demonstrated using gamma radiation to study three commercial devices spanning a range of integrated circuit complexity in 109 rad/min and 256 rad/min dose rate conditions. The demonstrated improvements in device lifetimes using the proposed dynamic biasing technique lays a foundation for more effective use of modern microelectronics for space applications. Analogous to the role real-time temperature monitoring plays in maximizing modern processor performance, the proposed dynamic biasing technique is a means of intelligently responding to the radiation environment and capable of becoming an integral tool in optimizing component lifetimes in space.

Agile methodologies applied to Integrated Concurrent Engineering for spacecraft design

In recent years, space projects have evolved to faster and more variable projects. To adjust the design processes in accordance, new work methodologies arise, as the Concurrent Engineering (CE). This working discipline is characterized by collaborative design and the flux of information being improved by working in a dedicated environment. CE has been recently adopted by space industry for the preliminary design phase of spacecrafts and other space systems. However, this methodology does not envisage tasks prioritization, which is a fundamental aspect to achieve an optimal design solution with an efficient allocation of resources. In this work a variation of CE discipline by applying Agile methodologies (in which the aspect of task prioritization is essential), is proposed. Agile methodologies allow the proper distribution of the design effort depending on the project priorities, the state of the design and the requirements, in a continuous process to improve the design solution. The general aspects of the proposed method are presented and applied to the design of a space mission, the results being analysed and compared with to the classical CE process in order to outline its differences and similarities with CE and Agile methodologies and show its potential for a new environment for space project design.

Icarus: In-situ monitoring of the surface degradation on a near-Sun asteroid

<div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Icarus is a mission concept designed to record the activity of an asteroid during a close encounter with the Sun. The primary science goal of the mission is to unravel the nontrivial mechanism(s) that destroy asteroids on orbits with small perihelion distances. Understanding the destruction mechanism(s) allows us to constrain the bulk composition and interior structure of asteroids in general. The Icarus mission does not only aim to achieve its science goals but also functions as a technical demonstration of what a low-cost space mission can do. The proposed space segment will include a single spacecraft capable of surviving and operating in the harsh environment near the Sun. The spacecraft design relies on the heritage of missions such as Rosetta, MESSENGER, Parker Solar Probe, BepiColombo, and Solar Orbiter. The spacecraft will rendezvous with an asteroid during its perihelion passage and records the changes taking place on the asteroid’s surface. The primary scientific payload has to be capable of imaging the asteroid’s surface in high resolution using visual and near-infrared channels as well as collecting and analyzing particles that are ejected from the asteroid. The payload bay also allows for additional payloads relating to, for example, solar research. The Icarus spacecraft and the planned payloads have high technology readiness levels and the mission is aimed to fit the programmatic and cost constraints of the F1 mission (Comet Interceptor) by the European Space Agency. Considering the challenging nature of the Icarus trajectory and the fact that the next F-class mission opportunity (F2) is yet to be announced, we conclude that Icarus is feasible as an F-class mission when certain constraints such as a suitable launch configuration are met (e.g., if EnVision is selected as M5). A larger mission class, such as the M class by the European Space Agency, would be feasible in all circumstances.</p> </div> </div> </div>

Small Mars Mission Architecture Study

While the vast majority of ESA’s funding for Mars exploration in the 2020s is planned to be invested in ExoMars and Mars Sample Return, there is an interest to assess the possibility of implementing a small mission to Mars in parallel with, or soon after, the completion of the MSR programme. A study was undertaken in the Concurrent Design Facility at ESA ESTEC to assess low-cost mission architectures for small satellite missions to Mars. Given strict programmatic constraints, the focus of the study was on a low-cost (<250MEuro Cost at Completion), short mission development schedule with a cost-driven spacecraft design and mission architecture. The study concluded that small, low-cost Mars missions are technically feasible for launch within the decade.