Bogdan Udrea

Embry–Riddle Aeronautical University · Department of Aerospace Engineering

The work presented in this paper leverages existing progress in angles-only navigation to develop optimal range observability maneuvers and trajectory planning methods for spacecraft formations under constrained relative orbital motion. Relative motion is modeled in the Clohessy-Wiltshire frame for proximity operations of multiple chaser spacecraft...

Impacts on planetary bodies can lead to both prompt secondary craters and projectiles that reimpact the target body or nearby companions after an extended period, producing so-called “sesquinary” craters. Here we examine sesquinary cratering on the moons of Mars. We model the impact that formed Voltaire, the largest crater on the surface of Deimos,...

The main goal of the lunar plants habitat project is to demonstrate germination of plants in lunar gravity and radiation environment. In 2015 scientists and engineers at NASA Ames will send a small payload module designed to place minimal requirements on the host spacecraft to show the potential for plants to grow on the moon. The goal of the resea...

This paper presents the concept of operations and preliminary design of a multi-satellite mission for the active removal of large pieces of debris from low Earth orbit. The mission consists of a mothership minisatellite, that carries six nanosatellites. The mothership acquires a relative orbit of a few kilometers with respect to the piece of orbita...

There has been an increasing interest in on-orbit autonomous servicing and repair of satellites as well as controlled active debris removal (ADR) in the space industry recently. One of the most challenging tasks for servicing/repair as well as for ADR is the rendezvous and docking with a non-cooperative tumbling resident space object (RSO). This pa...

This paper presents the concept of operations and preliminary design of a multi-satellite mission for the active removal of large pieces of debris from low Earth orbit. The mission consists of a mothership minisatellite, that carries six nanosatellites. The mothership acquires a relative orbit of a few kilometers with respect to the piece of orbita...

The work presented in this paper focuses on the design and analysis of an attitude determination and control subsystem (ADCS) for a proximity operation and imaging mission carried out by a 6 U CubeSat class nano-satellite. The satellite is equipped with a custom cold gas propulsion system which provides the capability for both orbital maneuvering a...

This paper discusses the application of a single beam laser rangefinder (LRF) to point cloud generation, shape detection, and shape reconstruction for a space-based space situational awareness (SSA) mission. The LRF is part of the payload of a chaser satellite tasked to image a Resident Space Object (RSO). The one-dimensional nature of LRF returns...

The work presented in this paper focuses on the design of an attitude determination and control subsystem (ADCS) for a proximity operation and imaging satellite mission. The ARAPAIMA (Application for Resident Space Object Proximity Analysis and IMAging) mission is carried out by a 6 U CubeSat class satellite equipped with a warm gas propulsion syst...

Recent inexpensive nanosatellite designs employ maneuvering thrusters, much as large satellites have done for decades. However, because a maneuvering nanosatellite can threaten high-­value assets (HVA) on-­orbit, it must provide a level of security typically reserved for HVAs. Securing nanosatellites with maneuvering capability is challenging due t...

Given a three-dimensional (3D) point cloud of a resident space object (RSO) and a chaser spacecraft with a scanning LIDAR, we need to determine the relative position, velocity, attitude, and rotational velocity between the spacecraft and the RSO. For this initial work, we assume that the relative position and velocity of the chaser spacecraft are k...

The main goal of the lunar plants habitat project is to demonstrate germination of plants in lunar gravity and radiation environment. In 2015 scientists and engineers at NASA Ames will send a small payload module designed to place minimal requirements on the host spacecraft to show the potential for plants to grow on the moon. The goal of the resea...

The main goal of the lunar plants habitat project is to demonstrate germination of plants in lunar gravity and radiation environment. In 2015 scientists and engineers at NASA Ames will send a small payload module designed to place minimal requirements on the host spacecraft to show the potential for plants to grow on the moon. The goal of the resea...

ARAPAIMA is a proximity operations mission sponsored by the US Air Force Office of Scientific Research and the Air Force Research Laboratory, to perform the in-orbit demonstration of proximity operations for visible, in-frared, and three dimensional imaging of resident space objects (RSOs) on a nanosat platform. The nanosat is of the 6U CubeSat cla...

This paper focuses on the aerospace application of a single beam laser rangefinder (LRF) for 3D imaging, shape detection, and reconstruction in the context of a space-based space situational awareness (SSA) mission scenario. The primary limitation to 3D imaging from LRF point clouds is the one-dimensional nature of the single beam measurements. A m...

This paper expands on previous studies by the authors into 3D imaging with a single-beam laser rangefinder (LRF) by implementing real-time attitude maneuvers of a chaser satellite flying in relative orbit around a resident space object (RSO). Point clouds generated with an LRF are much sparser than those generated with an imaging LIDAR, making it d...

ARAPAIMA is a proximity operations mission sponsored by the US Air Force Office of Scientific Research (AFOSR) and the Air Force Research Laboratory (AFRL) designed to perform the in-orbit demonstration of autonomous proximity operations and visible, infrared (IR) and three-dimensional imaging of Resident Space Objects (RSOs) from a nanosat platfor...

This paper addresses the feasibility of using point clouds generated with a single beam laser rangefinder (LRF) to reconstruct the three-dimensional shape of an unknown Resident Space Object (RSO), employing a combination of relative motion between the chaser and the RSO and chaser attitude motion. The first step in the analysis is the application...

Topical observations of the thermosphere at altitudes below $200 \, km$ are of great benefit in advancing the understanding of the global distribution of mass, composition, and dynamical responses to geomagnetic forcing, and momentum transfer via waves. The perceived risks associated with such low altitude and short duration orbits has prohibited t...

The dynamic behavior of the atmosphere between 200-500 km varies in relation to several factors, such as solar radiation and weather events in the thermosphere. To determine an accurate atmospheric model of this region there must be accurate measurements of total densities as well as composition and temperature of the particles. The average error d...

This paper describes the analysis of the touchdown footprint of an asteroid sample return mission. The mission bears similarity with NASA's Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission. The target asteroid is (101955) 1999 RQ 36 and the spacecraft mass and overall dimensions are similar to...

A prospecting mission with a human crew on board is planned to visit multiple near-Earth asteroids (NEAs); the number of NEAs visited is maximized across a mission timeline limited at three years with a minimum operations time at any NEA of five days. The paper describes the setup and results of an algorithm employed for preliminary asteroid target...

In order to decrease the risk of landing on an asteroid, a Light Detection and Ranging (LIDAR) system can be utilized. While in orbit the imaging LIDAR will generate a theoretically more detailed shape model than one which can be developed from Earth based observations. Using this model a more accurate gravitation field model can be generated on bo...

Small celestial bodies such as comets and asteroids are the target of space exploration missions which have invigorated noticeable interest in aerospace communities for nearby orbit designs. Among the requirements for planning such missions is an accurate model of their gravitational fields which serves even the most irregularly shaped bodies. This...

Improved finite element methodology for estimating small body gravitationnal fields is validated through numeric analyses of asteroid Itokawa. The model implements uniform spherical elements of two sizes to obtain a fill ratio that approximates the asteroid shape model geometry to nearly 100% efficiency. The gravitational model is applied to the ge...

Determining an accurate model of the atmosphere between 200-500km requires accurate measurements of total densities and composition. To do this, drag coefficients must be predicted with a level of accuracy surpassing previous drag satellites. This is achieved using the momentum transfer ratio and expressing the drag coefficient in terms of measurab...

The goal of the Dipping Thermospheric Explorer (DipTE) mission is to provide a data set that can be used to characterize the impact of gravity waves (GWs) on the thermosphere, and to open the door to many future thermospheric missions. The momentum deposited by dissipation of GWs which originate in the lower atmosphere and in the auroral region dri...

The major design driver for the Dipping Thermospheric Explorer (DipTE) CubeSat mission is that the satellite shall fly a significant amount of orbit arcs at altitudes of 300km and below. It is assumed that the DipTE satellite will be released in a circular orbit above the altitudes of scientific interest for the mission. A propulsion system will be...

An integrated approach to guidance, navigation and control (GNC) of formation flying spacecraft (sc) is introduced. The design process considers a three-sc mission in a reference geostationary transfer orbit (GTO). A detailed definition of the mission framework, in terms of GNC modes and corresponding science and technology requirements, is provide...

Solar sailing has been identified as a promising and enabling technology for future space missions; as such it is currently the object of a significant research effort within various space agencies, the academic world and industry. Active research and development activities have been performed by the European Space Agency (ESA) in the recent years...

In response to ESA's call for space science themes in the frame of Cosmic Vision 2015-2025, the scientific community identified a Far Infrared mission with very high spatial resolution as a potential future science mission for Europe. A future far infrared mission would typically work at wavelengths between 25-300 microns and combine high sensitivi...

This paper presents an integrated approach to GNC of formation flying spacecraft. The Navigation algorithm estimating the full relative state of all the spacecraft is a full-order decentralized filter, based on an Extended Kalman Filter for local measurements, and on Covariance Intersection for the fusion between local state estimates and estimates...

This paper presents the Design process of the GNC subsystem for a Formation Flying Demonstration Mission taking a GTO as reference orbit. In this process, the first step copes with a detailed definition of the mission framework, in terms of GNC modes and corresponding requirements and equipments. This, in conjunction with an analysis of the dynamic...

This paper focuses on the analytical and numerical design of optimal guidance low-thrust profiles for a three spacecraft formation during observation phase around apogee of a highly eccentric orbit. The objective is to maximise the observation time in which the constrained formation configuration shall remain stable, while minimising fuel consumpti...

This paper focuses on the design of analytical and numerical optimal guidance low-thrust profiles for a three spacecraft formation during observation phase around apogee of a highly eccentric orbit. The objective is to maximise the observation time in which the constrained formation configuration shall remain stable, while minimising fuel consumpti...

WOBBLE ("Water Observations from a Balloon Borne Light Explorer") is a mission concept study for a small robotic probe to explore Mars and to accomplish a scientific mission compatible with the goals of the NASA Code S enterprise. The detection of past or present water is a crucial goal for Mars exploration, representing a cross-cutting science the...

A collision avoidance methodology for satellite clusters is developed and simulated. A set membership algorithm is used to monitor and predict guaranteed position uncertainty ellipsoids over time. Distances between ellipsoids can be calculated on-line in order to evaluate when and how fast a collision may occur. The algorithm assumes guaranteed kno...

An implicit algorithm to model time-dependent magnetohydrodynamics (MHD) in three dimensions is described. The ideal MHD equations are hyperbolic, but the addition of resistivity and viscosity changes the mathematical form to mixed hyperbolic-parabolic. The algorithm is a finite volume implementation of a Roe-type approximate Riemann solver combine...

Formation flying is an enabling technique for numerous proposed satellite missions. The TeamAgent software system, based on ObjectAgent technology, is designed to enable multiple satellites to cooperate autonomously with particular focus on formation flying. A generalized agent-based software architecture for formation flying has been devised and i...

This paper will describe an advanced implicit algorithm for parallel architectures to model time-dependent magnetohydrodynamics (MHD) in all three dimensions. The algorithm is a finite volume implementation of a Roe-type approximate Riemann solver with central differenced diffusive terms combined with a lower-upper symmetric Gauss-Seidel iterative...

Thesis (Ph. D.)--University of Washington, 1999 A new implicit algorithm has been developed for the solution of the time-dependent, viscous and resistive single fluid magnetohydrodynamic (MHD) equations. The algorithm is based on an approximate Riemann solver for the hyperbolic fluxes and central differencing applied on a staggered grid for the par...

For a number of years the Aeronautics and Astronautics Department at the University of Washington has been developing a parallel, implicit, non-ideal MHD Riemann solver (WARP3). It is a distributed code based on the Message Passing Interface (MPI). Recently we have ported the code to a Quad Pentium 233 MHz machine. We used DEC Visual Fortran versio...

Our implicit, 3D approximate Riemann solver was developed for solving the time-dependent, non-ideal magnetohydrodynamic (MHD) equations. The algorithm is a finite-volume scheme, second order accurate in space and time, that uses an approximate Riemann solver for the hyperbolic fluxes and central differencing the parabolic fluxes that arise from the...

Summary form only given, as follows. A magnetic cumulative generator (MCG) is a pulsed power device that uses high velocity magnetohydrodynamic (MHD) flow to produce a large current pulse. A helical MCG consists of a solenoid and a cylindrical high explosive (HE) charge enclosed in an aluminum liner. The HE-liner assembly is coaxial with and placed...

Summary form only given. The magnetohydrodynamic (MHD) equations model the time evolution of plasmas and other conducting magnetofluids. Applications include electric plasma propulsion, magnetic confinement devices, and pulsed power generators. The MHD model is a set of mixed hyperbolic and parabolic equations. The hyperbolic component of the equat...

Summary form only given. The Helicity Injection Tokamak (HIT) has been upgraded to the “HIT-II” configuration. HIT-II extends coaxial helicity injection (CHI) to time scales longer than the wall resistive diffusion time. Previous results on HIT include production and sustainment of up to 250 kA of toroidal plasma current by CHI, without a transform...

Summary for only given, as follows. A spheromak is a force-free spherical plasma configuration that uses only internally generated magnetic fields to contain the plasma. It is known from linear theory that slightly prolate spheromaks are unstable to an m=1 mode tilt. Experimentally oblate spheromaks have also demonstrated a tilt instability. We are...

Summary for only given, as follows. Long duration higher power pulses have been used to create compact toroids. Pulses of 4800 amperes and up to 200 volts have been generated for 150 milliseconds duration. Pressure is held to 0.01 to 0.001 atmosphere. Compact toroids are observed to last for more than 200 milliseconds in atmosphere after all fields...

Summary form only given, as follows. This paper will describe an advanced implicit algorithm for parallel supercomputers to model time-dependent magnetohydrodynamics (MHD) in all three dimensions. The algorithm is a finite volume implementation of a Roe-type approximate Riemann solver with central differenced diffusive terms combined with a lower-u...

A plasma accelerator is a device that uses a combination of electric and magentic fields to provide the forces needed to accelerate the working fluid. One of the main uses of plasma accelerators is in space propulsion where the high velocity expulsion of plasma leads to high specific impulses. In this paper we present the results of a computer simu...