Optical Characterization of DebriSat Fragments in Support of Orbital Debris Environmental Models

The NASA Orbital Debris Program Office (ODPO) develops, maintains, and updates orbital debris environmental models, such as the NASA Orbital Debris Engineering Model (ORDEM), to support satellite designers and operators by estimating the risk from orbital debris impacts on their vehicles in orbit. Updates to ORDEM utilize the most recent validated datasets from radar, optical, and in situ sources to provide estimates of the debris flux as a function of size, material density, impact speed, and direction along a mission orbit. On-going efforts within the NASA ODPO to update the next version of ORDEM include a new parameter that highly affects the damage risk – shape. Shape can be binned by material density and size to better understand the damage assessments on spacecraft. The in situ and laboratory research activities at the NASA ODPO are focused on cataloging and characterizing fragments from a laboratory hypervelocity-impact test using a high-fidelity, mock-up satellite, DebriSat, in controlled and instrumented laboratory conditions. DebriSat is representative of present-day, low Earth orbit satellites, having been constructed with modern spacecraft materials and techniques. The DebriSat fragment ensemble provides a variety of shapes, bulk densities, and dimensions. Fragments down to 2 mm in size are being characterized by their physical and derived properties. A subset of fragments is being analyzed further in NASA’s Optical Measurement Center (OMC) using broadband, bidirectional reflectance measurements to provide insight into the optical-based NASA Size Estimation Model. Additionally, pre-impact spectral measurements on a subset of DebriSat materials were acquired for baseline material characterization. This paper provides an overview of DebriSat, the status of the project, and ongoing fragment characterization efforts within the OMC.

Out of Place in Outer Space?

Increasing human activity in orbital space has resulted in copious material externalities known as “orbital debris.” These objects threaten the orbital operations of hegemonic stakeholders including states, corporations, and scientists, for whom debris present a significant problem. We argue that the geographical imaginations of powerful stakeholders shape conceptions of orbital debris and limit engagement with these objects. By engaging with interdisciplinary literature that considers orbital debris and geographical imaginations of outer space, we encourage a more capacious approach to orbital debris that goes beyond hegemonic narratives focused on functionality. We explore the connections between debris and injustice, arguing that these objects must also be considered in relation to terrestrial power and ecology. We then contemplate the possibilities that counter-hegemonic framings present when considering speculative futures of orbital space. In these ways, we explore how and why debris are variously engaged with as pollutants, risks, opportunities, or otherwise.

Policies for incentivizing orbital debris assessment and remediation

Space debris threatens to destroy valuable space infrastructure, but damages from debris are not an inevitability. The scientific community has ideas for how to prevent the creation of new debris and limit the impact of pre-existing debris, but it will take government action to see that vision through. This essay unpacks how we know what we know, in service of ultimately discussing how policy-makers can use predictions of the long-term risks posed by satellites and debris on the orbital environment to more effectively prescribe behavior for operators. Financial incentives for sustainability, including taxation and cap-and-trade systems, have the potential to greatly benefit the safety and reliability of space missions, but they carry a variety of political and economic challenges, particularly at the international level. Now is a critical time to determine a policy strategy for debris management, because negotiations in the near-term may set valuable precedents for controlling the next century of debris proliferation.

Robotic Manipulation and Capture in Space: A Survey

Space exploration and exploitation depend on the development of on-orbit robotic capabilities for tasks such as servicing of satellites, removing of orbital debris, or construction and maintenance of orbital assets. Manipulation and capture of objects on-orbit are key enablers for these capabilities. This survey addresses fundamental aspects of manipulation and capture, such as the dynamics of space manipulator systems (SMS), i.e., satellites equipped with manipulators, the contact dynamics between manipulator grippers/payloads and targets, and the methods for identifying properties of SMSs and their targets. Also, it presents recent work of sensing pose and system states, of motion planning for capturing a target, and of feedback control methods for SMS during motion or interaction tasks. Finally, the paper reviews major ground testing testbeds for capture operations, and several notable missions and technologies developed for capture of targets on-orbit.

Tuning of NASA Standard Breakup Model for Fragmentation Events Modelling

The continuous growth of space debris motivates the development and the improvement of tools that support the monitoring of a more and more congested space environment. Satellite breakup models play a key role to predict and analyze orbital debris evolution, and the NASA Standard Breakup Model represents a widely used reference, with current activities relevant to its evolution and improvements especially towards fragmentation of small mass spacecraft. From an operational perspective, an important point for fragmentation modelling concerns the tuning of the breakup model to achieve consistency with orbital data of observed fragments. In this framework, this paper proposes an iterative approach to estimate the model inputs, and in particular, the parents’ masses involved in a collision event. The iterative logic exploits the knowledge of Two Line Elements (TLE) of the fragments at some time after the event to adjust the input parameters of the breakup model with the objective of obtaining the same number of real fragments within a certain tolerance. Atmospheric re-entry is accounted for. As a result, the breakup model outputs a set of fragments whose statistical distribution, in terms of number and size, is consistent with the catalogued ones. The iterative approach is demonstrated for two different scenarios (i.e., catastrophic collision and non-catastrophic collision) using numerical simulations. Then, it is also applied to a real collision event.

Self-healing materials for space applications: overview of present development and major limitations

In the last decade, self-healing materials have become extremely appealing for the field of space applications, due to their technological evolution and the consequent possibility of designing space systems and structures able to repair autonomously after damage arising from impacts with micrometeoroids and orbital debris, from accidental contact with sharp objects, from structural fatigue or simply due to material aging. The integration of these novel materials in the design of spacecraft structures would result in increased reliability and safety leading to longer operational life and missions. Such concepts will bring a decisive boost enabling new mission scenario for the establishment of new orbital stations, settlement on the Moon and human exploration of Mars.The proposed review aims at presenting the newest and most promising self-healing materials and associated technologies for space application, along with the issues related to their current technological limitations in combination with the effect of the space environment. An introductory part about the outlooks and challenges of space exploration and the self-healing concept is followed by a brief description of the space environment and its possible effects on the performance of materials. Self-healing materials are then analysed in detail, moving from the general intrinsic and extrinsic categories down to the specific mechanisms.