Research

Decisions

Multi-stage robust decision making under deep uncertainty

Long-term plans for space systems face deep uncertainty: even the probability distributions of future demand and technology maturation cannot be specified. We proposed multi-stage robust decision making (MSRDM), which formulates sequential decisions as a Markov decision process and finds worst- and best-case optimal policies by reinforcement learning.

MSRDMNomura, Doctoral dissertation 2020

A technology roadmap for orbital transfer vehicles

Applying robust decision making to an orbital transfer vehicle (OTV) roadmap, we identified the design parameters that drive economic viability through one million simulated cases and scenario discovery. The OTV's maximum total wet mass had the highest impact.

Pair plots of the restricted parameters for one of the boxes found by PRIM, with the box's projection drawn as red rectangles — OTV roadmapNomura et al., IAC 2025

Staged deployment of communication satellite constellations

Optical communication constellations in low Earth orbit need dozens of satellites, a large up-front investment under uncertain demand. Deploying them in stages lowers that cost and keeps the flexibility (real options) to decide each next step as demand emerges. With COSMICA, a modular simulator we developed, we evaluate each deployment path by the fraction of time without gateway visibility and the number of link interruptions.

COSMICA

Deploying a space logistics network

We optimized the deployment of a space logistics network under limited up-front costs, taking into account the economic path to its realization, with a case study of an asteroid mining and refueling business.

Space logistics

Space logisticsNomura et al., AIAA SPACE 2018, Fig. 3

Spacecraft

A systems engineering platform for satellite development

We propose a platform that integrates requirements, verification, development records, and knowledge, tracing each requirement to its verification results. Trial evaluations of existing tools showed their complementary strengths and the gaps between them, from which we outlined a lightweight, modular platform.

Systems engineering platform, Veriq, Capsula

The systems engineering platform: inside a project, a V&V platform, a development log database and a knowledge platform; outside it, a satellite development database and a cross-project decision-making support platform — Systems engineering platformNomura et al., Space Sciences and Technology Conference 2025

Managing satellite operation plans with OPMS

We developed OPMS, a web system automating the management, validation, and synchronization of operation plans, demonstrated it on SPHERE-1 EYE, and used it on ONGLAISAT.

OPMS, SPHERE-1 EYE, ONGLAISAT

OPMS at a glance: the user creates and edits an operation plan (control) and requests its validation (validate); the OPMS server schedules the validated plan on the satellite through the ground station software (synchronize) — OPMS

Attitude determination and control of EQUULEUS

I led the attitude determination and control system (ADCS) of EQUULEUS, a 6U CubeSat bound for an Earth–Moon Lagrange point, from initial design to hardware-in-the-loop simulation. After launch, we reported the initial operation results, centered on wheel unloading strategies for a deep-space 6U CubeSat.

EQUULEUS