صفحه 1:
Exploring the Solar System:
all about spacecraft/spaceflight
I. How can we explore the Solar System?
- types of space missions
II. How do we get there?
- launch & orbits
- gravity assist
- fuel/propulsion
III. Onboard Systems
- everything but the kitchen sink...
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صفحه 2:
. Planetary flyby
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Flyby Missions
usually the first phase of exploratio
(remember Mars & Mariner 4?
spacecraft following continuous orl
- around the Sun
- escape trajectory
(heading off into deep space)
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صفحه 3:
mous Example: VOYAGER 2
- launch 1977 with VOYAGER 1
- flew by Jupiter in 1979
- Saturn in 1980/1981
- Uranus (V2) in 1986
- Neptune in 1989 i’
- will continue to interstellar space
- study of interplanetary space مم 0
- data expected until 2020 ع
صفحه 4:
ther Flyby examples:
Underway: Stardust Comet return missio’
- launched in 1999
- interstellar dust collection
- asteroid Annefrank flyby
- Comet encounter (Jan 2004)
- Earth/sample return (Jan 2006)
صفحه 5:
Future flyby: Pluto-Kuiper Belt Mission
- to be launched in January 200
- swing by Jupiter (gravity assist
- fly by Pluto & moon Charon in
- then head into Kuiper Belt reg
(tons of solar system deb:
- to study objects that are like P
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صفحه 6:
2. Orbiter Spacecraft
Orbit insertion
* designed to travel to distant
planet & enter into orbit
around planet
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* must carry substantial pla
propulsion (fuel) capacity has
to withstand:
- staying in the ‘dark’ for periods of
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- staying out of touch with Earth for
periods of time
* usually the second phase of
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صفحه 7:
- why would a mission to Jupiter be called Galileo?
- launched in 1989 aboard Atlantis Space Shuttle
- entered into Jupiter’s orbit in 1995
- highly successful study of Jupiter & its moons
صفحه 8:
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- collect data about the atmosphere of a planet or planet’s
- usually piggy back on a bigger craft
- needs no propulsion of its own
- takes direct measurements of atmosphere
- usually is destroyed; rest of spacecraft continues its mis
ixample:
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صفحه 9:
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Probe Mission Events
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صفحه 10:
. Lander Spacecraft
- designed to reach surface of a planet/body
- survive long enough to transmit data back to Earth
- small, chemical experiments possible
Mars Viking
Lander
Many Successful Examples:
- Mars Viking Landers
- Venus Lander
- Moon Landers
(with humans!)
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صفحه 11:
Example: NEAR Asteroid Rendevous Mission
fly to a nearby asteroid: Eros - 1-2 AU orbit around Sun
Near-Earth Asteroid Eros ~ twice size of NYC
صفحه 12:
صفحه 13:
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صفحه 14:
Penetrator Spacecraft
- designed to penetrate the surface of a planet/body
- must survive the impact of many times the gravity on |
- measure 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
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صفحه 15:
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صفحه 16:
Rover Spacecraft
- electrically powered, mobile rovers
- mainly designed for exploration of Mars’ surface
- purposes: taking/analyzing samples with possibility of r
- Pathfinder was test mission - now being heavily develor
Mars Pathfinder
Mars Exploration Rovers
صفحه 17:
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n Earth orbit (or at Lagrange points
JASA’s “Great Observatories”:
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- Chandra (X-ray) SOHO
- 51۳71 (0عبه‌ظم)
- Compton (gamma-rays)
arge, complex scientific instruments
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lesigned to last > 5-10 years
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SIRTF (near-IR) Chandra (X-ray)
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صفحه 18:
1. First must leave the Earth’s surface
ده ماصذ "عجیممعع اقا
gets an initial boost via rocket
(0 go into Earth’s orbit - needs
an acceleration of 5 miles/sec
during orbit, you sometimes
1eed to adjust height of orbit
oy increasing/decreasing energy:
practically: firing onboard rocke
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a speed of 19,000 miles/hr
will keep craft in orbit around Eay|
صفحه 19:
using LEAST amount of
CORREA so aaves a 533 0b toh
2. To get to an outer orbit: Mars
spacecraft already in orbit (around Sun) ‘TRANSFER ORBIT APHELION
COINCIDES WITH MARS ORBIT
need to adjust the orbit - boost via rocket -
) that the spacecraft gets transferred from
arth’s orbit around Sun to Mars’ orbit around
put you want spacecraft to intercept Mars on|
انطاه "کرج]
بر مج هقی رای وت رات
AT TRANSFER ORBIT PERIHELION
to be captured by Mars - must decelerate
to LAND on Mars - must decelerate further &
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صفحه 20:
ing LEAST it of
ا so saves a 533 to bo toh
3. To get to an inner orbit: Venus
pacecraft already in orbit (around Sun) on Ea
ieed to adjust the orbit once off Earth to head
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nstead of SLOWING down (you'd fall to Earth)|
u use reverse motion in your solar orbit, effec
ywing down to land on Venus’ orbit
yut you want spacecraft to intercept Venus on
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natter of timing: small window every 19 months
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صفحه 21:
using LEAST amount of
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4. Gravity Assist
1 use the law of gravity to help spacecraft
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yager: its trajectory was aimed at ge}
piter’s orbit just after Jupiter
yager was gravitationally attracted tq ay cs f
er, and fell in towards Jupiter sists
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‘al energy decreased slightly
1 Voyager had more energy than waq
led to stay in orbit around Jupiter, a1
propelled outward!
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eated at Saturn & Uranus
صفحه 22:
At what speeds are these things traveling
through space?
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ound 20 km per second (72,000 km per/t
i example, is now moving
wards from the solar system at a speed o
km per second. At this rate, it would
e 85,000 years to reach the nearest star
p00 human generations!
Soe corerite ne Tonics Cb cero هم
1/10th of the velocity of light, it would
take a minimum of 40 years or so to
reach our nearest star.
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صفحه 23:
so aaves a 333 to bios موب و ول
5. Concerns about energy sources
- traditional energy boost: chemical thrusters
- most of energy is provided on launch - very costly!
especially for large, heavy, complex instruments
- a few times per year spacecraft fires short
bursts from its thrusters to make adjustments
- mostly free falling in orbit, coasting to destination
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صفحه 24:
sr مد مه ما
5. The Future: Ion Propulsion
- Xenon atoms are made of protons (+) and
electrons (-)
- bombard a gas with electrons (-) to c
charge
- creates a build up of IONS (+)
- use magnetic field to direct charged
- the IONS are accelerated out the back of craft
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this pushes the foresee To Moers direction
صفحه 25:
Xenon gas)
enters pipe
lectron
fenon atom ست Direction
Xenon ion of thrust
* to operate the ion system, use SOLAR panels
* sometimes called solar-electric propulsion
* can push a spacecraft up to 10x that of chemical
propulsion
* very gentle - best for slow accelerations
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صفحه 26:
HISTORY of ION PROPULSION
* 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
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صفحه 27:
- launched 27 September 2003 (Saturday)
حمتععنصط ۷۵2۲ 2-2.5 -
- will study lunar geochemistry
- search for ice at south Lunar pole
- **testing/proving of ion propulsion drives!**
1 2-2
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صفحه 28:
1. data handling 2. flight control
telecommuni
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صفحه 29:
Time & Money Considerations
nning for a new spacecraft
- plans start about ~10 years before projected launch da’
- must make through numerous hurdles/reviews
- very competitive: 1/10-25 average acceptance rate
! (circa 2000) - total NASA budget (2000) was $13 bil
c Assumptions for design/development of small craft:
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‘launch: $50M + $10M per AU + $10M per instrument
mission operations: $10M / month
speed: 3 months per AU of distance
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(e.g., for four instruments, double the travel time)
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صفحه 30:
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