The Falco orbital debris removal mission is a concept devised to provide a credible solution to removing a large piece of orbital debris from space for a reasonable mission cost. The target orbital debris for the mission is the defunct Infrared Astronomical Satellite (IRAS) telescope, which was chosen because it won't deorbit on its own, and because Ball Aerospace built it and so knows the details of the vehicle. The overall mission concept is very straightforward, except for the passive despin device that is used to simplify capture of the spinning spacecraft. The passive despin device is a novel method of reducing the spin rate of the orbital debris using the Earth's magnetic field, and helps to simplify the guidance, navigation, and control aspects of capturing a spinning piece of orbital debris. This paper will provide an overview of the mission, with a focus on the passive despin device and the simplifications it provides to the overall system.

In 2003 NASA commissioned a Science Definition Team (SDT) (Stokes, et al., 2003) to study the threats posed by Near‐Earth Objects (NEOs), recommend efficient methods for detecting NEOs down to 140 meters in diameter, and suggest conceptual mitigation techniques. In this same time frame, Congress set the goal of cataloguing 90% of all NEOs down to 140 meters diameter by 2020. The SDT concluded that the infrared passband from ∼5 to ∼11 microns is the best for finding NEOs; that an aperture of 50 centimeters is sufficient; and that locating a NEO‐finding observatory in a Venus‐like orbit is ideal. Since then, NASA and its industrial partners (such as Ball Aerospace) have flown two very NEO‐relevant deep‐space missions—the Spitzer Space Telescope and Kepler. Herein, a high‐reliability, credibly‐costed design is presented based on Spitzer and Kepler that meets the 90%/140‐m/2020 requirements for about $600 M. This design will also detect about 85% of all >100 meter NEOs, about 70% of all >65 meter NEOs, and about 50% of all >50 meter NEOs. These smaller NEOs constitute a newly recognized threat regime that cannot be efficiently found from the ground.In 2003 NASA commissioned a Science Definition Team (SDT) (Stokes, et al., 2003) to study the threats posed by Near‐Earth Objects (NEOs), recommend efficient methods for detecting NEOs down to 140 meters in diameter, and suggest conceptual mitigation techniques. In this same time frame, Congress set the goal of cataloguing 90% of all NEOs down to 140 meters diameter by 2020. The SDT concluded that the infrared passband from ∼5 to ∼11 microns is the best for finding NEOs; that an aperture of 50 centimeters is sufficient; and that locating a NEO‐finding observatory in a Venus‐like orbit is ideal. Since then, NASA and its industrial partners (such as Ball Aerospace) have flown two very NEO‐relevant deep‐space missions—the Spitzer Space Telescope and Kepler. Herein, a high‐reliability, credibly‐costed design is presented based on Spitzer and Kepler that meets the 90%/140‐m/2020 requirements for about $600 M. This design will also detect about 85% of all >100 meter NEOs, about 70% of all >65 meter NEOs, and ab...

In this paper we investigate the effects of several key system parameters related to development of a space-based observatory for discovering near-earth objects (NEOs). The space-based mission is seen as complementary to ground-based observations for identifying objects with the potential to impact the Earth. A system model is developed from an articial data set of 1218 NEOs with initial orbital elements generated from a probability distribution model similar to that incorporated in the NASA NEO Science Definition Team Report. By running the model over a 7 year period, the statistics of NEO detection can be investigated as a function of changes to telescope parameters. This paper discusses the system model development of orbital models, radiometric calculations and some initial results from parameter studies on the engineering design.

The Infrared Astronomical Satellite (IRAS) operates in a circular sun-synchronous orbit at 900 km. This orbit carries it through the radiation zones of the South Atlantic Anomaly and the polar regions. Penetrating radiation, mainly protons and electrons, produce spurious detector pulses which can be large compared to the outputs generated by infrared sources. To preserve the infrared (IR) sensitivity of the main IRAS instrument, pulse circumvention circuitry discriminates between signals from IR sources and those due to penetrating charged particles. This paper describes the pulse circumvention concept used and its implementation in the IRAS survey instrument. An analysis is given of the operation of the circuit and of the optimization of its parameters for maximum IR sensitivity. Early flight data validates the operation of the system. In the South Atlantic Anomaly a typical reduction in pulse generated system noise of two orders of magnitude is being obtained with this circuit.

A technique is presented for measuring many of the non-ideal characteristics of the large value [1E8 to 1E13 ohm] resistors used in the feedback loops of liquid helium cooled infrared (IR) detector circuits. These resistors are sensitive to both temperature and voltage and have a far from ideal response to transient events. Since these resistors are used to determine the transfer characteristics of a photodetector circuit, their non-ideal behavior can have a large effect on a system's photometric accuracy and linearity. They can also seriously degrade a system's signal to noise ratio in the presence of ionizing radiation. The method described in this paper has the sensitivity and versatility to accurately measure the non-linear characteristics of these resistors in the actual circuit configuration in which they will be used. This method relys upon the use of a small, stable, ceramic chip capacitor that is installed at the input summing node of a preamp, and an extremely narrow band, tuneable, RMS voltmeter. The capacitor is used to differentiate a number of controlled and well known input voltage waveforms into correspondingly well known input currents. These input currents flow through the resistor thereby creating the output voltage waveforms. These output waveforms contain information about the load resistor's electrical characteristics and allow the calibration of the resistor's response to a wide variety of signals. This method is useful in performing a dynamic system level calibration of a detector circuit since it simulates the many varied types of signal currents generated in either a photovoltaic or photoconductive IR detector circuit.

In 2003 NASA commissioned a Science Definition Team 3 (SDT) to study the threat posed by Near-Earth Objects (NEOs), to recommend solutions for efficiently detecting NEOs down to a much lower diameter than before, and to study techniques for mitigating an impending impact. Subsequently, the United States Congress directed NASA to investigate ways to implement many of the SDT's results. At this time Congress also set the goal of compiling a catalogue com- plete to 90% by 2020 of all NEOs larger than 140 meters in diameter. This 90%, 140 meter, 2020 set of goals was named in honor of George E. Brown, and is henceforth called the GEB require- ment. The SDT concluded that: the thermal infrared (~5 to ~11 microns) is the most efficient spectral regime for an efficient NEO search; that any IR aperture from about 50 to 100 centime- ters is sufficient; and that locating a NEO-finding observatory in a Venus-like orbit (approxi- mately a 0.7 AU semimajor axis) is ideal. The SDT had to make assumptions about future ad- vancements in detector technology and deep-space compatible processing power, and assumed that diffraction-limited optical systems with no chromatic aberrations were doable within the constraints of a flight mission. Since then, NASA and its industrial partners, of which Ball Aero- space is one of many, have flown several deep-space missions, two of which are very relevant here—the infrared Spitzer Space Telescope (SST), and the recently launched Kepler mission, as discussed later. In this paper we present a high reliability, credibly costed, high-heritage design that meets the GEB requirements for about $600M (USD). For no additional cost, this design will detect about 85% of all >100 meter diameter NEOs, about 70% of all >60 meter diameter NEOs, and about 50% of all >50 meter diameter NEOs. These smaller NEOs constitute a newly recognized threat regime that cannot be efficiently detected from the ground.