Prototyping Operational Autonomy for Space Traffic Management

Current state of the art in Space Traffic Management (STM) relies on a handful of providers for surveillance and collision prediction, and manual coordination between operators. Neither is scalable to support the expected 10x increase in spacecraft population in less than 10 years, nor does it support automated manuever planning. We present a software prototype of an STM architecture based on open Application Programming Interfaces (APIs), drawing on previous work by NASA to develop an architecture for low-altitude Unmanned Aerial System Traffic Management. The STM architecture is designed to provide structure to the interactions between spacecraft operators, various regulatory bodies, and service suppliers, while maintaining flexibility of these interactions and the ability for new market participants to enter easily. Autonomy is an indispensable part of the proposed architecture in enabling efficient data sharing, coordination between STM participants and safe flight operations. Examples of autonomy within STM include syncing multiple non-authoritative catalogs of resident space objects, or determining which spacecraft maneuvers when preventing impending conjunctions between multiple spacecraft. The STM prototype is based on modern micro-service architecture adhering to OpenAPI standards and deployed in industry standard Docker containers, facilitating easy communication between different participants or services. The system architecture is designed to facilitate adding and replacing services with minimal disruption. We have implemented some example participant services (e.g. a space situational awareness provider/SSA, a conjunction assessment supplier/CAS, an automated maneuver advisor/AMA) within the prototype. Different services, with creative algorithms folded into then, can fulfil similar functional roles within the STM architecture by flexibly connecting to it using pre-defined APIs and data models, thereby lowering the barrier to entry of new players in the STM marketplace. We demonstrate the STM prototype on a multiple conjunction scenario with multiple maneuverable spacecraft, where an example CAS and AMA can recommend optimal maneuvers to the spacecraft operators, based on a predefined reward function. Such tools can intelligently search the space of potential collision avoidance maneuvers with varying parameters like lead time and propellant usage, optimize a customized reward function, and be implemented as a scheduling service within the STM architecture. The case study shows an example of autonomous maneuver planning is possible using the API-based framework. As satellite populations and predicted conjunctions increase, an STM architecture can facilitate seamless information exchange related to collision prediction and mitigation among various service applications on different platforms and servers. The availability of such an STM network also opens up new research topics on satellite maneuver planning, scheduling and negotiation across disjoint entities

Space Traffic Management with a NASA UAS Traffic Management (UTM) Inspired Architecture

Space is becoming increasingly congested as the number of on-orbit satellites and debris objects continues to grow. Space traffic management (STM) is critical for ensuring that the expanding orbital population operates safely and efficiently, avoiding collisions and radio-frequency interference while still facilitating widespread space operations. Recent events such as the FCC approval of SpaceXs ~12,000 satellite constellation, the signing of Space Policy Directive 3 (which moves Space Situational Awareness responsibilities away from the Department of Defense and to a civil agency), and the growth in rideshare and small launch vehicles illustrate the rapidly changing nature of this domain. This paper will describe the concept of operations (ConOps) for a civilian STM research initiative, which has been developed from previous NASA work to enable safe operation of small unmanned aircraft systems. The STM ConOps proposes an architecture to enable efficient data sharing and coordination between participants to facilitate safe spaceflight operations. It is designed to utilize and promote the emerging field of commercial STM services, as a complement to existing government-provided STM services. The concept envisions a phased evolution that would gradually integrate additional capabilities, proposing a first phase architecture and tentative plans for a broader system. Work towards developing an STM research and prototyping platform is also discussed

A Concept for Civil Space Traffic Management

As technology has improved, operators have sought to use cubesats, as well as smallsats more generally, to perform increasingly more ambitious and sophisticated functions. Despite this, practical concerns associated with cubesat infant mortality, conjunctions, limited maneuverability, and debris generation have been relatively muted because most cubesats have been launched to lower orbits that limit both their orbital lifetime and consequences should a collision occur. NASA ARC has developed a concept for a highly-automated and distributed space traffic management (STM) architecture, drawing on similar work done to provide traffic management for small unmanned aerial systems (UAS) operating at low altitudes. The system proposes a strategy to accommodate growing space traffic volume safely, as well as pave the way for a transition of civil STM authority to a civilian governmental entity. The architecture envisions an open-access software platform architecture of data and service suppliers, consumers, and regulators, connected via a set of application programming interfaces (APIs). The platform would build on, rather than replicate existing integration and coordination efforts within the space situational awareness ecosystem, using existing standards for data message formats from organizations like the Consultative Committee for Space Data Systems and wrapping, rather than replacing existing integrations. We will present an initial STM architecture in this presentation, with a few examples showing how stakeholders can interact structurally, but flexibly, within this architecture

Public clonotype usage identifies protective Gag-specific CD8+ T cell responses in SIV infection

Despite the pressing need for an AIDS vaccine, the determinants of protective immunity to HIV remain concealed within the complexity of adaptive immune responses. We dissected immunodominant virus-specific CD8+ T cell populations in Mamu-A*01+ rhesus macaques with primary SIV infection to elucidate the hallmarks of effective immunity at the level of individual constituent clonotypes, which were identified according to the expression of distinct T cell receptors (TCRs). The number of public clonotypes, defined as those that expressed identical TCR β-chain amino acid sequences and recurred in multiple individuals, contained within the acute phase CD8+ T cell population specific for the biologically constrained Gag CM9 (CTPYDINQM; residues 181–189) epitope correlated negatively with the virus load set point. This independent molecular signature of protection was confirmed in a prospective vaccine trial, in which clonotype engagement was governed by the nature of the antigen rather than the context of exposure and public clonotype usage was associated with enhanced recognition of epitope variants. Thus, the pattern of antigen-specific clonotype recruitment within a protective CD8+ T cell population is a prognostic indicator of vaccine efficacy and biological outcome in an AIDS virus infection

The Capacity of Low Earth Orbit Computed using Source-sink Modeling

The increasing number of Anthropogenic Space Objects (ASOs) in Low Earth Orbit (LEO) poses a threat to the safety and sustainability of the space environment. Multiple companies are planning to launch large constellations of hundreds or thousands of satellites in the near future, increasing congestion in LEO and the risk of collisions and debris generation. This paper employs a new multi-shell multi-species evolutionary source-sink model, called MOCAT-3, to estimate LEO orbital capacity. In particular, a new definition of orbital capacity based on the stable equilibrium points of the system is provided. Moreover, an optimization approach is used to compute the maximum orbital capacity of the low region of LEO (200-900 km of altitude), considering the equilibrium solutions and the failure rate of satellites as a constraint. Hence, an estimate for the maximum number of satellites that it is possible to fit in LEO, considering the stability of the space environment, is obtained. As a result, considering 7% of failure rate, the maximum orbital capacity of LEO is estimated to be about 12.6 million satellites. Compatibility of future traffic launch, especially in terms of satellite constellations, is also analyzed and a strategy to accommodate for future traffic needs is proposed

Efficient search of optimal Flower Constellations

We derive an analytical closed expression to compute the minimum distance (quantified by the angle of separation measured from the center of the Earth) between any two satellites located at the same altitude and in circular orbits. We also exploit several properties of Flower Constellations (FCs) that, combined with our formula for the distance, give an efficient method to compute the minimum angular distance between satellites, for all possible FCs with up to a given number of satellites

Space sustainability rating: Designing a composite indicator to incentivise satellite operators to pursue long-term sustainability of the space environment

The Space Sustainability Rating (SSR) was first conceptualised within the World Economic Forum Global Future Council on Space Technologies, and is being designed by an international and transdisciplinary consortia including the World Economic Forum, Space Enabled Research Group at Massachusetts Institute of Technology (MIT) Media Lab, European Space Agency, University of Texas at Austin, and Bryce Space and Technology. With the increasing awareness of the rapidly growing number of objects in space, the implementation of a rating system, such as the SSR, provides an innovative way to address the orbital challenge by incentivising industry to design missions compatible with sustainable and responsible operations, and operate missions considering potential harm to the orbital environment and impact on other operators in addition to mission objectives and service quality. This paper builds upon the SSR concept introduced at the IAC in 2019, and provides in-depth description into the methodology used to design the SSR, based on successful rating systems in other industries such as LEED (green building energy and environmental design). This method seeks to provide a practice tool that governments, satellite operators and insurers can reference. The process also seeks to build capability among emerging space actors as they seek to understand how to design responsible space missions. The SSR is a composite indicator that is a function of the Space Traffic Footprint, measured through a mission index and compared to the so-called Environment Capacity and other measures of the responsibility shown by operator actions. The components of the SSR take into account mission aspects including on-orbit fragmentation risk, collision avoidance capabilities, detectability, identification, trackability, data sharing, on-orbit servicing, collision avoidance, debris mitigation, and adoption of international standards. The paper further explores key questions including; (i) what factors are most important to influence whether an operator seeks to reduce the potential for debris creation, (ii) how can the SSR can contribute to existing mechanisms (eg. UN Long-term Sustainability Guidelines, IADC) in supporting long-term space sustainability, and (iii) how can the SSR educate policy makers regarding manufacturers' and operators' motivations in choosing specific criteria and certifications in designing their mission to achieve a high rating or improve their existing rating