Piloted operations at a near-Earth object (NEO)

In late 2006, NASA's Constellation Program sponsored a study to examine the feasibility of sending a piloted Orion spacecraft to a near-Earth object. NEOs are asteroids or comets that have perihelion distances less than or equal to 1.3 astronomical units, and can have orbits that cross that of the Earth. Therefore, the most suitable targets for the Orion Crew Exploration Vehicle (CEV) are those NEOs in heliocentric orbits similar to Earth's (i.e. low inclination and low eccentricity). One of the significant advantages of this type of mission is that it strengthens and validates the foundational infrastructure of the United States Space Exploration Policy and is highly complementary to NASA's planned lunar sortie and outpost missions circa 2020. A human expedition to a NEO would not only underline the broad utility of the Orion CEV and Ares launch systems, but would also be the first human expedition to an interplanetary body beyond the Earth–Moon system. These deep space operations will present unique challenges not present in lunar missions for the onboard crew, spacecraft systems, and mission control team. Executing several piloted NEO missions will enable NASA to gain crucial deep space operational experience, which will be necessary prerequisites for the eventual human missions to Mars.Our NEO team will present and discuss the following:

• new mission trajectories and concepts;

• operational command and control considerations;

• expected science, operational, resource utilization, and impact mitigation returns; and

• continued exploration momentum and future Mars exploration benefits.

Decision program on asteroid threat mitigation

The Association of Space Explorers Committee on Near-Earth Objects (NEOs) and its Panel on Asteroid Threat Mitigation have prepared a decision program to aid the international community in organizing a coordinated response to asteroid impact threats. The program is described in the ASE's report, Asteroid Threats: A Call for Global Response, which will be considered by the United Nations Committee on the Peaceful Uses of Outer Space in its 2009 sessions. The findings and recommendations of this report are presented here as well as some of the major implications of the complex decision-making involved in developing a coordinated international response to the challenge of protecting the Earth from NEO impacts.     

Design of a formation of solar pumped lasers for asteroid deflection

This paper presents the design of a multi-spacecraft system for the deflection of asteroids. Each spacecraft is equipped with a fibre laser and a solar concentrator. The laser induces the sublimation of a portion of the surface of the asteroid, and the resultant jet of gas and debris thrusts the asteroid off its natural course. The main idea is to have a formation of spacecraft flying in the proximity of the asteroid with all the spacecraft beaming to the same location to achieve the required deflection thrust. The paper presents the design of the formation orbits and the multi-objective optimisation of the formation in order to minimise the total mass in space and maximise the deflection of the asteroid. The paper demonstrates how significant deflections can be obtained with relatively small sized, easy-to-control spacecraft.     

ASTEX: An in situ exploration mission to two near-Earth asteroids

ASTEX (ASTeroid EXplorer) is a concept study of an in situ exploration mission to two Near-Earth-Asteroids (NEAs), which consists of an orbiting element and two individual lander units. The target candidates have different mineralogical compositions, i.e. one asteroid is chosen to be of “primitive’’ nature, the other to be a fragment of a differentiated asteroid. The main scientific goals of the ASTEX mission are the exploration of the physical, geological, and mineralogical nature of the NEAs. The higher level goal is the provision of information and constraints on the formation and evolution of our planetary system. The study identified realistic mission scenarios, defined the strawman payload as well as the requirements and options for the spacecraft bus including the propulsion system, the landers, the launcher, and assessed and defined the requirements for the mission’s operational ground segment.     

Impacting small Near Earth Objects

The design of a low-cost spacecraft to impact on a small, faint Near Earth Object (NEO), poses major challenges. This paper focuses on the terminal phase of such impact mission, analyzing the capability of autonomous Guidance, Navigation and Control (GNC) systems to compensate the deviations in the impact point to achieve a successful collision. The autonomous GNC system employs the information of the optical sensors to estimate the parameters allowing the computation of divert maneuvers to achieve the impact. GMV has developed a simulator, with different levels of sophistication, and a set of different GNC algorithms to help in the design process. This tool is used for different purposes such as: dimensioning the sensors and actuators, verifying mission requirements, computing figures of merit of different SC configurations and evaluating GNC performances. Four GNC algorithms are compared: low-thrust proportional navigation using a fading memory filter, high-thrust predictive guidance using either a Kalman filter or a batch-sequential least-squares filter, and a mid-thrust hybrid predictive-proportional guidance using a fading memory filter. Monte Carlo analysis using global-performances models of the optical sensors for each of these GNC algorithms are presented for two different asteroids (1989 ML and 2002 AT4), showing the mission parameters driving the mission performances. In addition, single-runs with high-fidelity optical sensors models are presented to validate the Monte Carlo simulations.