Mission Scheduling Research Articles

Behavioral and biological effects of autonomous versus scheduled mission management in simulated space-dwelling groups

Logistical constraints during long-duration space expeditions will limit the ability of Earth-based mission control personnel to manage their astronaut crews and will thus increase the prevalence of autonomous operations. Despite this inevitability, little research exists regarding crew performance and psychosocial adaptation under such autonomous conditions. To this end, a newly-initiated study on crew management systems was conducted to assess crew performance effectiveness under rigid schedule-based management of crew activities by Mission Control versus more flexible, autonomous management of activities by the crews themselves. Nine volunteers formed three long-term crews and were extensively trained in a simulated planetary geological exploration task over the course of several months. Each crew then embarked on two separate 3–4 h missions in a counterbalanced sequence: Scheduled, in which the crews were directed by Mission Control according to a strict topographic and temporal region-searching sequence, and Autonomous, in which the well-trained crews received equivalent baseline support from Mission Control but were free to explore the planetary surface as they saw fit. Under the autonomous missions, performance in all three crews improved (more high-valued geologic samples were retrieved), subjective self-reports of negative emotional states decreased, unstructured debriefing logs contained fewer references to negative emotions and greater use of socially-referent language, and salivary cortisol output across the missions was attenuated. The present study provides evidence that crew autonomy may improve performance and help sustain if not enhance psychosocial adaptation and biobehavioral health. These controlled experimental data contribute to an emerging empirical database on crew autonomy which the international astronautics community may build upon for future research and ultimately draw upon when designing and managing missions.

From Discrete Mission Schedule to Continuous Implicit Trajectory using Optimal Time Warping

This paper presents a generic solution to apply a mission described by a sequence of tasks on a robot while accounting for its physical constraints, without computing explicitly a reference trajectory. A naive solution to this problem would be to schedule the execution of the tasks sequentially, avoiding concurrency. This solution does not exploit fully the robot capabilities such as redundancy and have poor performance in terms of execution time or energy. Our contribution is to determine the time-optimal realization of the mission taking into account robotic constraints that may be as complex as collision avoidance. Our approach achieves more than a simple scheduling; its originality lies in maintaining the task approach in the formulated optimization of the task sequencing problem. This theory is exemplified through a complete experiment on the real HRP-2 robot.

Regional surveillance of disjoint rectangles: a travelling salesman formulation

Mission planning for surveillance coverage is of both practical and theoretical interest. In brief, regional surveillance involves planning the search of certain given regions in the minimum possible time. The surveillance problem can therefore be described as a variant of the classical travelling salesman problem. The uniqueness of the problem lies in the different allowed entry and exit points. Additionally, the mission schedule has to ensure the probability of target detection must not be compromised. From the practical perspective, any reduction in travelling time provides immediate cost savings to the defence department. A dynamic programming formulation is derived for the regional surveillance problem. An example is included to illustrate the methodology.

유전 알고리즘을 이용한 위성 임무 스케줄링 최적화

A mission scheduling optimization algorithm according to the purpose of satellite operations is developed using genetic algorithm. Satellite mission scheduling is making a timetable of missions which are slated to be performed. It is essential to make an optimized timetable considering related conditions and parameters for effective mission performance. Thus, as important criterions and parameters related to scheduling vary with the purpose of satellite operation, those factors should be fully considered and reflected when the satellite mission scheduling algorithm is developed. The developed algorithm in this study is implemented and verified through a comprehensive simulation study. As a result, it is shown that the algorithm can be applied into various type of the satellite mission operations.

Searching satellites of asteroid Itokawa by imaging observation with Hayabusa spacecraft

Abstract We carried out a search for satellites around Itokawa, the target asteroid of the Japanese Hayabusa mission. An imaging instrument, AMICA, on the spacecraft was used to take four images of Itokawa and its vicinity on September 1, 2005. The distance of the spacecraft from Itokawa was approximately 1,700 km, somewhat longer than the original plan (1,000 km) due to the mission schedule. The field-of-view of AMICA corresponded to 170 km × 170 km around Itokawa. Since the Hill sphere of Itokawa was estimated to be 33 km at the time of the observations, the images completely covered the detectable area of satellites. However, we cannot find the motion of Itokawa satellites between the four images, because the observation period was set to 2 hr due to the mission schedule and the region where satellites would be observable was only within 8 km of Itokawa, which is inside the extensive glare of Itokawa on the images. In addition, high-energy protons produced by a huge solar flare impacted the spacecraft during the observations, and hence the four images suffered from many random spots. Comparing the positions of the spots with catalogued stars, we managed to identify stellar images. No evidence of satellites was found. Additionally, we evaluated the 1-m detection limit of the images from the limiting magnitude of 9.5. The absence of satellites of Itokawa is consistent with past optical and radar observations as well as other results by the Hayabusa spacecraft.

Real-Time Optimal Mission Scheduling and Flight Path Selection

We consider a mission in which m UAVs with a capacity limit q each visit n(les mq) targets in a hostile environment in a cooperative manner (and return to where they departed from) such that the cost reflecting operating time and risk exposed is minimized. We first propose a mixed-integer linear programming (MILP) formulation which exactly solves the problem and then propose four alternative MILP formulations which are computationally less intensive and, therefore, suited for real-time purposes, but yield a theoretically guaranteed suboptimal solution. The main contributions of this note are an exact but compact MILP formulation, using a room concept, and four nonexact formulations, each one of which ensures a certain level of solution quality and relatively fast computational time for the considered real-time mission scheduling problem.

Operator Performance and Intelligent Aiding in Unmanned Aerial Vehicle Scheduling

Interest is increasing in designing systems for controlling unmanned vehicles that will invert the current many-to-one ratio of operators to UVs. Instead of the lower-level tasks that today's UV teams perform, a single operator would focus on high-level supervisory control. A key challenge in designing such single-operator systems is to minimize periods of excessive workload that arise when critical tasks for several UVs occur simultaneously. So, we need decision support that helps the operator evaluate different action alternatives for managing a multiple-UV mission schedule in real time. Two decision support experiments have attempted to provide operators of unmanned aerial vehicles with multivariate scheduling assistance, with mixed results. Those automated decision support tools that provided more local, as opposed to global, visual recommendations performed better. This result suggests that meta-information displays could saturate operators and reduce performance. This article is part of a special issue on Interacting with Autonomy.

The Surface Structure of the M-Type Asteroid 21 Lutetia: Spectral and Frequency Analysis

A preliminary study of the surface of the asteroid 21 Lutetia with ground-based methods is of sig- nificant importance, because this object is included into the Rosetta space mission schedule. From August 31 to November 20, 2000, about 50 spectra of Lutetia and the same number of spectra of the solar analog HD10307 (G2V) and regional standards were obtained with a resolution of 4 and 3 nm at the MTM-500 telescope televi- sion system of the Crimean astrophysical observatory. From these data, the synthetic magnitudes of the asteroid in the BRV color system have been obtained, the reflected light fluxes have been determined in absolute units, and its reflectance spectra have been calculated for a range of 370-740 nm. In addition, from the asteroid reflec- tance spectra obtained at different rotation phases, the values of the equivalent width of the most intensive absorption band centered at 430-440 nm and attributed to hydrosilicates of the serpentine type have been cal- culated. A frequency analysis of the values V (1, 0) confirmed the rotation period of Lutetia 0. d 3405 (8. h 172) and showed a two-humped light curve with a maximal amplitude of 0. m 25 . The color indices B-V and V-R showed no noticeable variations with this period. A frequency analysis of the equivalent widths of the absorp- tion band of hydrosilicates near 430-440 nm points to the presence of many significant frequencies, mainly from 15 to 20 c/d (c/d is the number of cycles per day), which can be caused by a heterogeneous distribution of hydrated material on the surface of Lutetia. The sizes of these heterogeneities (or spots) on the asteroid surface have been estimated at 3-5 to 70 km with the most frequent value between 30 and 40 km.

Mass Medical Repatriation of Injured Civilians after Terrorist Attack in Mombassa, Kenya: Medical Needs, Resources Used, and Lessons Learned

On 28 November 2002, three suicide bombers crashed their car into a hotel in Mombassa, Kenya; 12 people were killed, including three Israelis, and 80 were wounded (22 of whom were Israeli). The Israeli Defense Force Airborne Medical Evacuation Flight Teams participated in a repatriation mission to bring the wounded home. The objectives of this study are to outline the distinctive aspects of this mission, as well as to share the experiences and lessons learned. Israeli Army debriefing reports were used to study the composition of the crew, medical equipment taken, injury distribution, mode of operation, and mission schedule. A total of six fixed-wing aircraft were used--two Boeing 707s and four Hercules C-130s--with a total of 54 medical team members on board. A total of 260 Israelis were repatriated, 22 of whom were wounded, and three were dead. Of the casualties, 14 were conveyed sitting, and eight supine. The time from the first landing in Kenya to the evacuation of the last supine patient was 5.5 hours. Nurses, as well as social workers, played a central role in the mission. A forward team, including five doctors, was used for the initial organization and for gathering information on the medical status of the casualties. There was redundancy in the medical crew and medical equipment sent. The need for improved infrastructure on the medical aircraft was stressed. Based on this experience, a new mode for operation for similar missions in the future was formulated.

A Hybrid Intelligent Logistics Diagnostic Assistant

Artificial neural networks (ANN) are powerful tools for pattern matching and have proven useful in fault detection and diagnosis. Rule based systems (RBS) have the ability to process complex reasoning paths and explain the results of an analysis. The Hybrid Intelligent Logistics Diagnostic Assistant (HILDA) combines these technologies to augment the abilities of a logistics analyst. HILDA aids a logistics analyst working with the Mobility Aircraft Availability Forecasting (MAAF) simulation in trying to balance the requirements of a mission schedule versus the personnel and aircraft resources available at a set of airbases. This paper describes the design and implementation of the hybrid architecture, with details on the domain specific knowledge embedded in the ANN and RBS modules. Examples show how the HILDA prototype is successful in aiding a decision maker in converging to a successful mission/resource scenario.

Continuous management of airlift and tanker resources: A constraint-based approach

Efficient allocation of aircraft and aircrews to transportation missions is an important priority at the USAF Air Mobility Command (AMC), where airlift demand must increasingly be met with less capacity and at lower cost. In addition to presenting a formidable optimization problem, the AMC resource management problem is complicated by the fact that it is situated in a continuously executing environment. Mission requests are received (and must be acted upon) incrementally, and, once allocation decisions have been communicated to the executing agents, subsequent opportunities for optimizing resource usage must be balanced against the cost of solution change. In this paper, we describe the technical approach taken to this problem in the AMC barrel allocator, a scheduling tool developed to address this problem and provide support for day-to-day allocation and management of AMC resources. The system utilizes incremental and configurable constraint-based search procedures to provide a range of automated and semi-automated scheduling capabilities. Most basically, the system provides an efficient solution to the fleet scheduling problem. More importantly to continuous operations, it also provides techniques for selectively reoptimizing to accommodate higher priority missions while minimizing disruption to most previously scheduled missions, and for selectively “merging” previously planned missions to minimize nonproductive flying time. In situations where all mission requirements cannot be met, the system can generate and compare alternative constraint relaxation options. The barrel allocator technology is currently transitioning into operational use within AMC's Tanker/Airlift Control Center (TACC). A version of the barrel allocator supporting airlift allocation was first incorporated as an experimental module of the AMC's Consolidated Air Mobility Planning System (CAMPS) in September 2000. In May 2003, a new tanker allocation module is scheduled for initial operational release to users as part of CAMPS Release 5.4.

Operational Report of the Mission Analysis and Planning System for the KOMPSAT-I

Since its launching on 21 December 1999, the Korea Multi-Purpose Satellite-I (KOMPSAT-I) has been successfully operated by the Mission Control Element (MCE), which was developed by the ETRI. Most of the major functions of the MCE have been successfully demonstrated and verified during the three years of the mission life of the satellite. This paper presents the operational performances of the various functions in MAPS. We show the performance and analysis of orbit determinations using ground-based tracking data and GPS navigation solutions. We present four instances of the orbit maneuvers that guided the spacecraft from injection orbit into the nominal on-orbit. We include the groundbased attitude determination using telemetry data and the attitude maneuvers for imaging mission. The event prediction, mission scheduling, and command planning functions in MAPS subsequently generate the spacecraft mission operations and command plan. The fuel accounting and the realtime ground track display also support the spacecraft mission operations.

DESIGN AND IMPLEMENTATION OF THE MISSION PLANNING FUNCTIONS FOR THE KOMPSAT-2 MISSION CONTROL ELEMENT

Spacecraft mission planning functions including event prediction, mission scheduling, command planning, and ground track display have been developed for the KOMPSAT-2 mission operations. Integrated event prediction functions including satellite orbital events, user requested imaging events, and satellite operational events have been implemented. Mission scheduling functions have been realized to detect the mission conflicts considering the user specified constraints and resources, A conflict free mission scheduling result is mapped into the spacecraft command sequences in the command planning functions. The command sequences are directly linked to the spacecraft operations using eXtensible Markup Language(XML) for command transmission. Ground track display shows the satellite ground trace and mission activities on a digitized world map with zoom capability.

Gravity field and rotation state of Mercury from the BepiColombo Radio Science Experiments

The ESA mission BepiColombo will include a Mercury Planetary Orbiter equipped with a full complement of instruments to perform Radio Science Experiments. Very precise range and range-rate tracking from Earth, on-board accelerometry, altimetry and accurate angular measurements with optical instruments will provide large data sets. From these it will be possible to study (1) the global gravity field of Mercury and its temporal variations due to tides, (2) the medium to short scale (down do 300≃400 km ) gravity anomalies, (3) the rotation state of the planet, in particular the obliquity and the libration with respect to the 3/2 spin orbit resonance and (4) the orbit of the center of mass of the planet. With the global gravity field and the rotation state it is possible to tightly constrain the internal structure of the planet, in particular to determine whether the solid surface of the planet is decoupled from the inner core by some liquid layer, as postulated by dynamo theories of Mercury's magnetic field. With the gravity anomalies and altimetry it is possible to study the geophysics of the planet's crust, mantle and impact basins. With the orbit of the planet closest to the Sun it is possible to constrain relativistic theories of gravitation. The possibility of achieving these scientific goals has been tested with a full cycle numerical simulation of the Radio Science Experiments. It includes the generation of simulated tracking and accelerometer data, and the determination, by least squares fit, of a long list of variables including the initial conditions for each observed arc, calibration parameters, gravity field harmonic coefficients, and corrections to the orbit of Mercury. An error budget has been deduced both from the formal covariance matrices and from the actual difference between the nominal values used in the data simulation and the solution. Thus the most complete error budget contains the effect of systematic measurement errors and is by far more reliable than a formal one. For the rotation experiment an error budget has been computed on the basis of dedicated studies on each separate error source. The results of the full cycle simulation are positive, that is the experiments are feasible at the required level of accuracy. However, the extraction of the full accuracy results from the data will be by no means trivial, and there are a number of open problems, both in the data processing (e.g., the selection of the orbital arc length) and in the mission scheduling (e.g., the selection of the target areas for the rotation experiment).

Operating a telescope larger than the Earth: How the VSOP space VLBI mission is scheduled

Abstract The Japanese VLBI space observatory programme (VSOP) mission is one of the most complex scientific endeavors ever attempted. It involves coordinating a spacecraft with detailed pointing constraints that vary on time scales ranging from years to hours, tracking stations in four different countries, ground radio telescopes in nearly 20 different countries with different capabilities at the VSOP observing frequencies, and correlation and tape copying facilities with four different recording formats. Scientific constraints on the quality of (u,v)-coverage obtainable force the scheduling to be done far in advance of the observation — over about 1.5 years time — so that the sources are observed when the orbital orientation is most favorable. In order that all these facilities work as a single astronomical instrument, the constraints on them also must be taken into account in the scheduling to the satisfaction of all parties involved, including the principal investigators as well as mission and observatory personnel. In this paper we outline the entire VSOP mission scheduling process. Special emphasis is placed on software required to decide when to observe the proposed sources and how to ensure the highest quality science while preserving the health of the spacecraft. We also discuss application of the process to the future space VLBI missions VSOP2, RadioAstron, and ARISE.

Operating a Telescope Larger than the Earth: How to Schedule the HALCA Space VLBI Mission

AbstractWe outline the HALCA Space VLBI mission scheduling process, with special emphasis placed on software that decides when to observe the proposed sources and how to ensure that the highest quality science is obtained. This information will be useful to the many principal investigators whose very high resolution VLBI observations are being supported by the mission.

Reflective correctors for the Hubble Space Telescope axial instruments

Reflective correctors to compensate the spherical aberration in the Hubble Space Telescope are placed in front of three of the axial scientific instruments (a camera and two spectrographs) during the first scheduled refurbishment mission. The five correctors required are deployed from a new module that replaces the fourth axial instrument. Each corrector consists of a field mirror and an aspherical, aberration-correcting reimaging mirror. In the camera the angular resolution capability is restored, be it in reduced fields, and in the spectrographs the potential for observations in crowded areas is regained along with effective light collection at the slits.

Systems approach to the satellite operations problem

It is noted that the projected increase in satellites needed to satisfy future military, scientific, and commercial missions will soon be overwhelming current ground-operations capabilities. An intelligent processing architecture, IntelliSTAR, that addresses the potential of automating the entire satellite operations domain (planning, scheduling, execution, and analysis) is discussed. The architecture has been developed with flexibility in mind. In particular, IntelliSTAR has been structured to allow for development and validation on the ground, prior to deployment in space. The overall architecture is described, with particular emphasis placed on the scheduling of satellite missions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Mission scheduling

We investigate through a mission scheduling problem how a neural network can work compared to a hybrid system based on an operations research and artificial intelligence approach. Then we present a discussion to demonstrate the characteristic features of each.

El Chichon as seen from Project Airstream

In April 1982, and again in July, while flying at 17–19 km on regularly scheduled missions, DOE's WB‐57F aircraft (flown by NASA/Johnson Space Center) successfully intercepted the plume from the April 1982 eruption of El Chichon in Mexico. These flights are part of DOE's high‐altitude sampling program (HASP), which provides data three times a year—April, July, and October—on the distribution of radioactivity and various nonnuclear compounds in the troposphere and the stratosphere.Project Airstream, the aircraft part of HASP, is a cooperative effort, with Robert Leifer of DOE's Environmental Measurements Laboratory (EML) as the scientific director. On the April and July missions the aircraft had aboard instruments from four laboratories: EML, Los Alamos, NASA/Johnson Space Center, and the Atmospheric Environment Service of Canada. The samples collected are being analyzed at each laboratory, and the results will be presented at the American Geophysical Union Fall Meeting in San Francisco.