Space Mission Analysis

Dr. Andrew KetsdeverMAE 5595

Space Mission Design• Advantages of Space

– Global perspective– Clear view of the heavens– Free-fall environment– Abundant resources– Final frontier

Space Mission Design• Many different types of design processes, which do

we use?– All, or maybe none of them! All attempt to solve basic

problem of optimizing performance, cost, and time

Just depends on what you’re trying to accomplish (must consider project goals, constraints, background of group solving, etc)

• We’ll standardize on SMAD process for this class

Performance Cost

Schedule

Optimum design space

System Engineering Process• A System:

– An integrated composite of people, products, and processes that provide a capability to satisfy a stated need or objective

• Defense Acquisition University, “System Engineering Fundamentals”

Systems Engineering• The System Engineering Process covers

the development, manufacturing, verification, testing, operations, and disposal of a system

Subject

Orbit andConstellation

Space Element

Launch ElementGroundElement

Operations

C3

Space Mission Design Process

FireSat (SMAD Example)

FireSat Objectives

FireSat Functional Requirements

FireSat Operational Requirements

FireSat ConstraintsConstraint

Analysis of Alternatives

Analysis of Alternatives

FireSat Mission Summary

Space Mission Design• Form follows function• Spacecraft are designed and

built to perform specific missions

• Spacecraft share certain traits based upon intended purpose

• So, a Spacecraft’s appearance can give us a clue about its mission.

ISS: Subject• Low-Earth Orbit

– 407 km circular orbit, 51.6 deg inclination.

• NASA plans six research facilities – fluids and combustion– materials science – gravitational biology– human free-fall

adaptation.

Hubble: Subject

• Low-Earth Orbit– 590 km circular, 28.5 deg

inclination.• Optics: The telescope is

an f/24 Ritchey-Chretien Cassegrainiansystem with a 2.4 m diameter primary mirror and a 0.3 m Zerodursecondary.– Effective focal length is

57.6m.

Cassini: Subject

• Interplanetary - Capture– 2 flybys of Venus, Jupiter flyby,

Saturn orbit. (VEVJ Gravity Assist)

• The Cassini spacecraft is a scientific platform designed to perform an in-depth study of the Saturnian system. – Atmosphere– Magnetosphere– Rings – Several moons. – Titan's atmosphere was

investigated by the ESA built Huygens probe

Voyager: Subject• Interplanetary – Escape• Between them, Voyager 1 and 2

made numerous discoveries (Grand Tour)– new moons about several of the

planets– Jupiter’s Rings– Uranus' unique magnetic field– Volcanic activity on Io

• Following their final planetary encounters, the vehicles began the Voyager Interstellar Mission (VIM), which will measure interstellar fields, particles, and waves to the outer limits of the Sun's sphere of influence– Both spacecraft will eventually depart

our solar system and will travel towards other star systems.

DMSP: Subject• Earth Polar Orbit

– 820-860 km, polar, sun-synchronous • DMSP 5D-2 was the military's

sixth generation of weather satellites.

• The DMSP 5D-2 satellites operated in two-satellite constellations to provide world-wide meteorological, oceanographic and solar-terrestrial measurements on a twice-daily basis.– The visible and infrared sensors

collected images of global cloud distribution across a 3,000 km swath during both daytime and night time conditions.

DSP: Subject• Geosyncronous Earth

Orbit• DSP is the 2nd

generation DSP Ballistic Missile Early Warning Satellite.

• Payload includes 3.6 m Schmidt telescope with 2000 element IR sensor, nuclear detection sensors.

Explorer I: Subject• Low-Earth Orbit

– Perigee: 347 km (215 mi). Apogee: 1,859 km (1,155 mi). Inclination: 33.20 deg.

• First US Launched Satellite– 1 Feb 1958

• Discovered Van Allen radiation belts. Spacecraft engaged in research and exploration of the upper atmosphere or outer space.

GPS: Subject• Medium Earth Orbit Constellation

– 24 satellites in six planes – Circular 20,200 km / 12-hour orbits

• GPS provides the following: – 24-hour, worldwide service – Extremely accurate, three-

dimensional location information (providing latitude, longitude, and altitude readings)

– Extremely accurate velocity information

– Precise timing services – Continuous real-time information – Accessibility to an unlimited number

of worldwide users

Communications Satellites:Subject

• LEO Constellations to GEO Single Satellite Architectures

• Provides a variety of services– Sopranos– Social Distortion– Phone calls to Mom– Sat to Sat Comm

Satellite Characteristics

System Milstar DSCS UFO DSP GPS IIA, IIR DMSP Weight (lb) 10,000 2,550 3,050 5,200 2,050; 2,370 2,544 Size (ft) 52 x 108 6.8 x 6.3 x 6.4

w/38 span 7.5 cube w/61

span32.8 L x 14

diameter 18 x 18;

5 x 6.3 x 6.3 33.3 x 13.4

Orbit GEO at 5° GEO equatorial

GEOequatorial

GEO Semi-synch 10,898NM at 55

Sun-synch

ConstellationSize

4 5 operational, 6 residuals

8 Classified 24 sats in 6 planes

2 sats in 2 planes

First Launch Feb 94 DSCS I: Nov 71 DSCS III: Oct 82

Sep 93 1970 II in 89 IIA in 90 IIR in 96

Dec 82

Launcher Titan IV/ Centaur

Atlas IIA Atlas II Titan IV/IUS or Shuttle

Delta II Titan II

Mission Area MILSATCOM EHF

MILSATCOMSHF

MILSATCOMUHF & EHF for mobile

user

Space-basedEarly Warning

Navigation & Nuclear

Detonation Detection

Meteorology/ Environmental

sensing