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'Sec. 632 if plane change also required. 'Sec. 632 if plane change also required. relative to the body as when it approached, but in a different direction. This phenomenon is like the elastic collision between a baseball and a bat in which the velocity of the ball relative to the bat is nearly the same, but its velocity relative to the surrounding baseball park can change dramatically. We can use flybys to change direction, to provide increased heliocentric energy for solar system exploration,...

Secondary Design Variables

Determines latitude distribution of coverage Compare latitude coverage vs. launch costs * Select best coverage among discrete phasing options * Mission complexity and coverage vs. cost Normally zero nonzero may reduce number of satellites needed Coverage overlap needed cross-track pointing Minimize consistent with low-cost maintenance approach Any mechanism that allows you to clean up after yourself 7.6.1 Coverage and Constellation Structure For most constellations, Earth coverage is the key...

Sa

Unregulated Bus Using Parallel Batteries Unregulated Bus Using Linear Charge Current Control Recharge Control Quasi-Regulated Bus with Constant Current Chargers Fig. 11-13. Techniques for Power Regulation. The basic approaches are Peak Power Tracking (PPT), which places a regulator hi series with the solar arrays and the load, and Direct Energy Transfer (DET), which uses a regulator in parallel with the solar arrays and load. loads or battery charging do not need power. Power subsystems with...

Step 1 Definition of Mission Objectives

The first step in analyzing and designing a space mission is to define mission objectives the broad goals which the system must achieve to be productive. Figure 1-4 shows sample objectives for FireSat We draw these qualitative mission objectives largely from the mission statement In contrast, the mission requirements and constraints discussed in Sec. 1.4 are quantitative expressions of how well we achieve our objectives balancing what we want against what the budget will allow. Thus, whereas we...

Space Payload Design and Sizing

Air Force Academy Reinhold Lutz, Daimler Chrysler Aerospace Robert F. Brodsky, Microcosm, Inc. 9.1 Payload Design and Sizing Process 9.2 Mission Requirements and Subject Trades Subject Trades The Electromagnetic Spectrum Basic Telescope Optics Diffraction Limited Resolution Candidate Sensors and Payioads Payload Operations Concept Required Payload Capability Signal Processing and Data Rates Estimating Radiometric Performance Estimating Size, Weight, and Power Evaluate...

The Space Environment and Survivability

The Solar Cycle The Gravitational Field and Microgravity The Upper Atmosphere Plasmas, the Magnetic Field, and Spacecraft Charging Radiation and Associated Degradation 8.2 Hardness and Survivability Requirements The Nuclear Weapons Environment and Its Effect on Space Systems Other Hostile Environments Spacecraft Hardening Strategies for Achieving Survivability Alan C. Tribble, Intellectual Insights D J. Gorney, J.B. Blake, H.C. Koons, M. Schulz, A.L. Vampola, R.L. Walterscheid, The Aerospace...

Step 4 Identifying Alternative Mission Architectures

A mission architecture consists of a mission concept plus a specific set of options for the eight mission elements defined in Sec. 1.2. Although we need all of the elements to define and evaluate a mission architecture, some are more critical than others in determining how the space mission will meet its objectives. Typically, we define a mission architecture by specifying the mission concept plus the subject, oibit, communications architecture, and ground system. These provide a framework for...

Step 5 Identifying System Drivers

System drivers are the principal mission parameters or characteristics which influence performance, cost, risk, or schedule and which the user or designer can control. For example, the temperature at which a forest fire bums may heavily influence how easily it can be detected however, this is beyond the system designer's control and, therefore, is not a system driver. Correctly identifying the key system drivers is a critical step in mission analysis and design. Misidentifying system drivers is...

Step 3 Identifying Alternative Mission Concepts

The broad mission concept is the most fundamental statement of how the mission will work that is, how it gets its data or carries out the mission to satisfy the end user's needs. The mission concept as we are using it here consists of the four principal elements in Table 2-1. Notice that most of these elements are somehow associated with data or information. Except for manufacturing in space and a small number of other space payloads, most space missions are concerned fundamentally with the...

Introduction to Astrodynamics

Flight Path Angle

Boden, United States Naval Academy Satellite Equations of Motion Constants of Motion Classical Orbital Elements Satellite Ground Tracks Time of Flight in an Elliptical Orbit Orbit Determination 62 Orbit Perturbations Third-Body Perturbations Perturbations Because of a Nonspherical Earth Perturbations from Atmospheric Drag Perturbations from Solar Radiation Coplanar Orbit Transfers Orbit Plane Changes Orbit Rendezvous 6.4 Launch Windows 6 J Orbit Maintenance Astrodynamics is the study...

Orbit and Constellation Design

Analytic Approximations', Numerical Simulations', Coverage Figures of Merit 7.4 Selecting Orbits for Earth-Referenced Spacecraft 7.5 Selecting Transfer, Parking, and Space-Referenced Orbits Selecting a Transfer Orbit, Parking and Space-Referenced Orbits Coverage and Constellation Structure Summary of Constellation Design Chapters 5 and 6 introduced the geometry and physics of spacecraft orbits, as well as formulas for computing orbit parameters. In contrast, this chapter deals with selecting or...

Rf

Communications tolerance to interference scintillation. Multiple links, processing, modulation and frequency choices. Prior to the end of the Cold War, fixed ground control stations were high priority targets of ICBM-launched nuclear weapons. Therefore, satellites needed to be autonomous or capable of being controlled by multiple mobile ground control stations, or utilize a combination of the two survivability features. In the Post-Cold War era, these survivability features are less important...