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All about Spacecraft presentation

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Exploring the Solar System: all about spacecraft/spaceflight

How do we get there? launch & orbits gravity assist fuel/propulsion

How can we explore the Solar System?types of space missions

Onboard Systems everything but the kitchen sink…

1. Flyby Missions

usually the first phase of exploration (remember Mars & Mariner 4?) spacecraft following continuous orbit - around the Sun - escape trajectory(heading off into deep space)

Famous Example: VOYAGER 2

launch 1977 with VOYAGER 1flew by Jupiter in 1979Saturn in 1980/1981Uranus (V2) in 1986Neptune in 1989will continue to interstellar spacestudy of interplanetary space particles (Van Allen)data expected until 2020

Other Flyby examples. Underway: Stardust Comet return mission

launched in 1999 interstellar dust collection asteroid Annefrank flyby Comet encounter (Jan 2004) Earth/sample return (Jan 2006)

Future flyby: Pluto-Kuiper Belt Mission

to be launched in January 2006swing by Jupiter (gravity assist*)fly by Pluto & moon Charon in 2015then head into Kuiper Belt region(tons of solar system debris)to study objects that are like Pluto

2. Orbiter Spacecraft

designed to travel to distant planet & enter into orbit around planet must carry substantial propulsion (fuel) capacity has to withstand: staying in the ‘dark’ for periods of timeextreme thermal variationsstaying out of touch with Earth for periods of time usually the second phase of exploration

Famous Example: Galileo

why would a mission to Jupiter be called Galileo?launched in 1989 aboard Atlantis Space Shuttle entered into Jupiter’s orbit in 1995highly successful study of Jupiter & its moons

3. Atmospheric Spacecraft

relatively short mission collect data about the atmosphere of a planet or planet’s moon usually piggy back on a bigger craft needs no propulsion of its own takes direct measurements of atmosphereusually is destroyed; rest of spacecraft continues its mission

Example: Galileo’s atmospheric probe

traveled with Galileo for nearly six yearstook five months from release to contact with atmospherecollected 1 hour’s data IN Jupiter’s atmosphere

4. Lander Spacecraft

designed to reach surface of a planet/bodysurvive long enough to transmit data back to Earthsmall, chemical experiments possible

Many Successful Examples: Mars Viking LandersVenus LanderMoon Landers (with humans!)

Example: NEAR Asteroid Rendevous Mission

fly to a nearby asteroid: Eros – 1-2 AU orbit around Sun

5. Penetrator Spacecraft

designed to penetrate the surface of a planet/bodymust survive the impact of many times the gravity on Earthmeasure properties of impacted surface

No Currently Successful Examples:Deep Space 2 (lost with Mars Polar Lander)But more to come in future:“Ice Pick” Mission to Jupiter’s Moon Europa“Deep Impact” Mission to a Comet

6. Rover Spacecraft

electrically powered, mobile roversmainly designed for exploration of Mars’ surfacepurposes: taking/analyzing samples with possibility of returnPathfinder was test mission – now being heavily developed

7. Observatory Spacecraft

in Earth orbit (or at Lagrange points)NASA’s “Great Observatories”: Hubble (visible)Chandra (X-ray)SIRTF (infrared)Compton (gamma-rays)Large, complex scientific instrumentsup to 10-20 instruments on boarddesigned to last > 5-10 years

How do we get there?

must ‘escape’ into orbitgets an initial boost via rocketto go into Earth’s orbit – needsan acceleration of 5 miles/secduring orbit, you sometimes need to adjust height of orbitby increasing/decreasing energy:practically: firing onboard rocketthrustersa speed of 19,000 miles/hrwill keep craft in orbit around Earthars

1. First must leave the Earth’s surface

How do we get there?

spacecraft already in orbit (around Sun)need to adjust the orbit – boost via rocket –so that the spacecraft gets transferred fromEarth’s orbit around Sun to Mars’ orbit around Sunbut you want spacecraft to intercept Mars onMars’ orbitmatter of timing: small window every 26 monthsto be captured by Mars – must decelerateto LAND on Mars – must decelerate further &use braking mechanism

2. To get to an outer orbit: Mars

How do we get there?

spacecraft already in orbit (around Sun) on Earthneed to adjust the orbit once off Earth to head inwards to Venusinstead of SLOWING down (you’d fall to Earth), you use reverse motion in your solar orbit, effectively slowing down to land on Venus’ orbitbut you want spacecraft to intercept Venus onVenus’ orbitmatter of timing: small window every 19 monthsnism

3. To get to an inner orbit: Venus

How do we get there?

can use the law of gravity to help spacecraftpropel themselves further out in the SSVoyager: its trajectory was aimed at gettingto Jupiter’s orbit just after JupiterVoyager was gravitationally attracted toJupiter, and fell in towards JupiterJupiter was “tugged on” by Voyager and itsorbital energy decreased slightlythen Voyager had more energy than wasneeded to stay in orbit around Jupiter, andwas propelled outward!repeated at Saturn & Uranus

4. Gravity Assist

At what speeds are these things traveling through space?

The currently fastest spacecraft speeds are around 20 km per second (72,000 km per/hr)For example, Voyager 1 is now moving outwards from the solar system at a speed of 16 km per second. At this rate, it would take 85,000 years to reach the nearest star 3,000 human generations!Even assuming that we could reach a speed of 1/10th of the velocity of light, it would still take a minimum of 40 years or so to reach our nearest star. anus

How do we get there?

traditional energy boost: chemical thrustersmost of energy is provided on launch – very costly!especially for large, heavy, complex instrumentsa few times per year spacecraft fires shortbursts from its thrusters to make adjustmentsmostly free falling in orbit, coasting to destinationanus

5. Concerns about energy sources

How do we get there?

Xenon atoms are made of protons (+) and electrons (-)bombard a gas with electrons (-) to change chargecreates a build up of IONS (+)use magnetic field to direct charged particlesthe IONS are accelerated out the back of craftthis pushes the craft in the opposite directionanus

6. The Future: Ion Propulsion

to operate the ion system, use SOLAR panelssometimes called solar-electric propulsioncan push a spacecraft up to 10x that of chemical propulsionvery gentle – best for slow accelerations


first ion propulsion engine – built in 1960 over 50 years in design/development at NASA very new technology has been used successfully on test mission: Deep Space 1

Europe’s Lunar Explorer: Smart 1 Probe

launched 27 September 2003 (Saturday)2-2.5 year missionwill study lunar geochemistrysearch for ice at south Lunar pole**testing/proving of ion propulsion drives!**

Onboard Systems on Most Spacecraft: Galileo

1. data handling 2. flight control 3. telecommunications 4. electrical power 5. particle shields 6. temperature control7. propulsion mechanism 8. mechanical devices (deployment)

Time & Money Considerations

Planning for a new spacecraft plans start about ~10 years before projected launch datemust make through numerous hurdles/reviewsvery competitive: 1/10-25 average acceptance rate

Costs! (circa 2000) – total NASA budget (2000) was $13 billion Basic Assumptions for design/development of small craft: Cost of spacecraft and design: $50MCost of launch: $50M + $10M per AU + $10M per instrumentCost of mission operations: $10M / monthInitial speed: 3 months per AU of distanceFor every additional instrument, add $100M and increase travel time by 25% (e.g., for four instruments, double the travel time)A probe, lander, or balloon counts as two additional instruments.If you are going to the outer Solar System (Jupiter or beyond), you must add plutonium batteries, which count as one instrument.