AsterAnts is a concept calling for a fleet of solar sail powered spacecraft to retrieve large numbers of small (1/2-1 meter diameter) Near Earth Objects (NEOs) for orbital processing. AsterAnts could use the International Space Station (ISS) for NEO processing, solar sail construction, and to test NEO capture hardware. Solar sails constructed on orbit are expected to have substantially better p...

Precision Doppler tracking of deep-space probes is central to spacecraft navigation and many radio science investigations. The most sensitive Doppler observations to date have been taken using the NASA/JPL Deep Space Network (DSN) antenna DSS 25—a 34-m-diameter beam-waveguide station especially instrumented with simultaneous X-band (≈8.4-GHz) and Ka-band (≈32-GHz) links and tropospheric scintil...

Prospective designs of microwave power amplifiers for on-board equipment service systems are considered, in which the problem minimizing area occupied by them on a thermally stabilized plate spacecraft is solved. Microwave provide good heat dissipation and require degree redundancy. Each included redundant amplifier made boards located perpendicular to heat-stabilized fixed one or both sides. T...

In this paper, formation control ideas for multiple spacecraft using the virtual structure approach are presented. If there is no formation feedback from the spacecraft to the virtual structure, the spacecraft will get out of formation when the virtual structure moves too fast for the spacecraft to track due to spacecraft control saturation or the total system must sacrifice convergence speed i...

It is well known that three momentum wheel actuators can be used to control the attitude of a rigid spacecraft and that arbitrary reorientation maneuvers of the spacecraft can be accomplished using smooth feedback. If failure of one of the momentum wheel actuators occurs, we demonstrate that two momentum wheel actuators can be used to control the attitude of a rigid spacecraft and that arbitrar...

In this paper, a quaternion-based finite-time sliding mode attitude controller is designed for a spacecraft performing high-thrust orbital maneuvers, with cold gas thrusters as its actuators. The proposed controller results are compared with those of a quaternion feedback controller developed for the linearized spacecraft dynamics, in terms of settling time, steady-state error, number of thrust...

Current state-of-the-art commercial sensors and actuators do not meet many of NASA’s next generation spacecraft and instrument needs. Nor do they satisfy the DoD needs for satellite missions, especially micro/nano satellite missions. In an effort to develop advanced optical devices and instruments that meet mission requirements, NASA Langley recently completed construction of a new cleanroom ho...

The radiation exposure in space missions can be reduced by appropriate measures, but it cannot be prevented. The reason is that space radiations due to their high energy deeply penetrates in matter. In comparison to the shielding thickness of the atmosphere of approximately 10 meter water equivalent, a spacecraft provides only 1-30 cm shielding depending on the equipment installed inside the sp...

Formation control for multiple vehicles has become an active research area in recent years. Generally there are three approaches to this problem, namely leaderfollowing, behavioral, and virtual structure approaches. In this paper, formation control ideas for multiple spacecraft using virtual structure approach are presented. If there is no formation feedback from spacecraft to the virtual struc...

This paper considers the problem of rotating a constellation of spacecraft using on/oo thrusters such that the relative distance between the spacecraft is maintained to within a speciied tolerance. The basic idea is to resolve all of the constraints into a sphere around the desired tra-jectory of each spacecraft. As the constellation rotates, the sphere sweeps out a tube that constrains the mot...