Sustainability takes off — from Earth

Purdue College of Engineering
Purdue Engineering Review
4 min readMar 12, 2024

Sustainability isn’t just a quest on Earth; it extends into outer space as well.

Sustainability is a way of life — and a way to ensure that life endures, wherever we are. Sustainable space exploration and utilization will enable us to explore and use space — Earth orbits, cislunar space, our solar system, and beyond — with little to no reliance on resources on Earth. Currently, our space activities depend on Earth in various aspects, including communication with ground antennas; deployment of new spacecraft and space systems; and supplies for humans (such as water and food) and spacecraft (such as fuel and spare parts).

This goal can be achieved when we establish an ecosystem in space comparable to what we have on Earth, including transportation, resource mining, manufacturing, assembly, and machine maintenance.

Several elements are vital for sustainable space exploration and utilization. We must have efficient and dependable space transportation to support robotic and crewed activities. We need in-situ resource utilization on the moon, asteroids, and planets to create water, fuel, and other supplies in space. And we require on-orbit satellite servicing (inspection, repairing, and refueling); assembly; and manufacturing (OSAM) in Earth orbits, cislunar space, and beyond.

Each element requires advanced spaceflight technologies. Space mission design and trajectory optimization are must-haves for efficient and reliable space transportation. Spacecraft guidance navigation control (GNC) and space autonomy with guaranteed safety (e.g., no collision with other spacecraft, and sustained solar power generation) are essential for in-situ resource utilization, and for OSAM operations without frequent commands from human operators.

We also must enable spaceflight that fully leverages natural environments in space — for example, using multi-body gravitational fields, atmospheric drag, and solar radiation — for efficient space transportation and resource utilization with minimal fuel cost.

My research group focuses on advancing these key technologies via analytical and computational means. We are developing new mathematical models, algorithms, and frameworks to optimize space trajectories, autonomously plan safe maneuvers and sensing, and design missions and science orbits.

My research team is growing this effort through collaboration with other faculty members and research groups. Our research efforts have been aided greatly by working with other faculty members via the Purdue Engineering Initiative in Cislunar Space, which brings together researchers from various schools in engineering and science to enable the joint use of cislunar space.

In addition, we are working with Purdue’s Institute for Control, Optimization and Networks (ICON), which draws faculty from many Purdue schools as well as outside experts.

Access to ICON is extremely helpful to my team in advancing sustainable space exploration and utilization. Our interdisciplinary research lies at the intersection of astrodynamics, optimization, and controls, mapping nicely to the collective expertise of ICON researchers. For example, we use knowledge and techniques in mathematics and physics for analytical work, while employing and developing tools from engineering and computer science.

Some of these tools and innovations are in astrodynamics, which encompasses orbital mechanics, spacecraft attitude dynamics, and spaceflight techniques. This involves dynamical systems theory applied to space transportation path discoveries and nonlinear or convex optimization techniques for mission/trajectory optimization and planning. We also work with control and estimation theory — including optimal control, robust control, stochastic control, nonlinear control, and nonlinear filtering — for space autonomy and GNC.

We are also combining techniques from machine learning, such as reinforcement learning, to introduce adaptability to the space autonomy capabilities, as well as supervised learning, for efficient mission design and trajectory optimization.

Autonomous optical navigation via lunar images along a transfer between halo orbits in cislunar space. Kenshiro Oguri, Purdue assistant professor of aeronautics and astronautics, is co-leading a multi-university research project named CHANCE as a co-principal investigator, aiming to make cislunar space transportation and navigation more sustainable and reliable. (Purdue University image/Oguri Research Group. Relevant paper: The Journal of the Astronomical Sciences: “Analysis of Autonomous Orbit Determination in Various Near-Moon Periodic Orbits”)

A major breakthrough of my research group is the development of advanced space autonomy and mission design techniques that can deal with uncertainty in the system and environment — enabled by fusing astrodynamics, stochastic optimal control, optimization, and dynamical systems theory. We have been collaborating with such space agencies as NASA and the Japan Aerospace Exploration Agency (JAXA), as well as private companies, to further the various technologies.

Innovations in these technologies also will expand our capabilities in space-based sciences like astronomy (space telescopes and interferometers with precise orbit/attitude control), planetary science (agile exploration of distant planetary systems with enhanced autonomy), and Earth science (autonomous operation of remote sensing satellites).

Fusing various fields of research is a key to discovering efficient and reliable space transportation paths, which even extends to Saturn exploration and beyond. (Purdue University image/Oguri Research Group, from a paper from the 2023 AAS/AIAA Astrodynamics Specialist Conference: “Low-thrust Trajectory Optimization for Enceladus Exploration using Indirect Forward-Backward Shooting”)

This work will contribute to a number of space sectors. NASA will benefit from advancement in cislunar space utilization, planetary exploration and science, and astronomical observations. The private sector will gain from spaceflight technologies for in-situ resource utilization, on-orbit satellite servicing, and remote sensing. Government will be enhanced through advanced space situational awareness and spacecraft autonomy in Earth orbits, cislunar space, and beyond.

And humanity will be served — through more discoveries in the universe that satisfy our intellectual curiosity — by the provision of goods that are difficult to acquire or create on Earth, and by the additional option of living outside the Earth.

Kenshiro Oguri, PhD

Assistant Professor, School of Aeronautics and Astronautics

Director, Oguri Research Group

Faculty Council Member, Purdue Engineering Initiative in Cislunar Space

Faculty Contributor, Institute for Control, Optimization and Networks (ICON)

College of Engineering

Purdue University