the space environment

The Space Environment

Unit 1, Chapter 3, Lesson 3: The Space Environment 2

The Space Environment The Cosmic Perspective

Where Is Space? The Solar System The Cosmos

The Space Environment and Spacecraft Challenges of the Space Environment Gravity Atmosphere Vacuum Micrometeoroids and Space Junk The Radiation Environment Charged Particles

Living and Working in Space Hazards to Humans in Space Free Fall Radiation and Charged Particles Mental and Emotional Effects

Packing for a Trip

Where’d you go on Spring Break? Would you have packed differently if

you were going to Alaska?

It is vital to know something about the environment you visit in order to know what you’re up against

Unit 1, Chapter 3, Lesson 3: The Space Environment SECTION 3.1 4

The Cosmic Perspective

Where is space? The solar system The cosmos

“Cosmos” = orderly arrangement (Greek)


Where Is Space? No clear definition of where space begins

US Air Force’s Astronaut Wings awarded for those who achieve 92.6 kilometers (57.6 miles)

For astronautics, space begins when an object can maintain an orbit for a short time about 130 kilometers (81 miles) altitude

Perspective for low-Earth orbit: if the Earth were a peach, most satellites would be just above the “fuzz”

Spaceship One: 328,000’

WHERE EARTH’S ATMOSPHERE ENDS


The Solar System: The Sun

The Sun generates every second enough energy to supply the U.S. for 624 million years

600 million tons of hydrogen burned per second in nuclear fusion


The Sun: Radiation Sun sends energy in

the form of electromagnetic (EM) radiation Radiation travels in

waves Sun’s EM radiation has

many wavelengths: radio waves, infrared (heat), visible light, ultra-violet, x-rays and gamma rays


Electromagnetic (EM) Radiation

We classify Electromagnetic radiation in terms of the wavelength (or frequency) of the energy

Electromagnetic (EM) Radiation


The Sun: Charged Particles

The intense heat from nuclear fusion breaks atoms into basic building blocks: Protons Electrons Neutrons (quickly decay

into an electron and a proton)

The Sun’s magnetic field propels these particles toward us at high speed: solar wind

The Atom


The Sun: Solar Flares

Areas of the Sun’s surface sometimes erupt in solar flares

Flares can extend as far as the Earth’s orbit

Generate more energy than many nuclear weapons

11 year cycles: next peak in 2011


The Planets Aside from the Sun,

other players in the solar system are Planets Moons Asteroids

For most space missions, Earth is the primary player Gravitation Atmosphere Magnetic field


The Cosmos

Solar system is part of the Milky Way Galaxy—about half way from the center

Galaxy rotates once every 240 million years

Next closest star in the galaxy—Proxima Centauri—is 4.22 light years away

Galactic Distances

= One Cosmic Year


The Cosmos

What is a light year? Distance light can travel in one year

An interplanetary probe traveling at 35,000 m.p.h. would take 80,000 years to get to Proxima Centauri


Stellar Distances

Sun is marble 1 inch in diameter: in Denver, Colorado

Nearest star Proxima Centauri is 932 miles away: in Chicago, Illinois

Milky Way Galaxy is 21 million miles across

Stellar Distances


Challenges of the Space Environment

Gravity / Free fall Atmosphere Vacuum Micrometeoroids

and Space Junk Electromagnetic

Radiation Charged Particles


Gravity and Free-fall Not “zero gravity”

Low-Earth orbit is about 91% of gravity at sea level

Physical impacts on equipment Methods to measure quantities on Earth not

effective Plumbing must be pressurized—no “gravity feed”

Advantages Opportunity to develop super alloys and

pharmaceuticals Heavier ingredients in materials won’t settle to the

bottom


Shuttle depends on drag to slow down from orbital speed to landing speed

Few particles above 600 kilometers altitude (375 miles)

DragSpacecraft slow down when they run into particles in the upper atmosphere

Slower speeds mean less energy and smaller orbitIf uncorrected, will eventually re-enter

The Atmosphere:

Drag


RUST

OXIDATION


The Atmosphere: Oxygen Most oxygen near Earth’s surface in the

form of “O2” (two oxygen atoms bound together)

Oxygen in upper atmosphere has trouble finding a “partner,” so it exists as “O” (monatomic oxygen)

Weakens structures Changes thermal properties of coatings Degrades sensors

Refer to P. 91 in book


Pressure


Impact of a Near-Vacuum

Outgassing Gasses kept inside

materials by atmosphere’s pressure may be “coaxed” out by near-zero pressure

Escaping gasses can cloud sensors

Spacecraft are “baked” in hot vacuum chambers before being launched into space Thermal vacuum chamber


Impact of a Near-Vacuum (cont’d)

Cold Welding No air layer between contacting parts Moving parts tend to bind

Limited Heat Transfer Convection and conduction are options to

transfer heat only within the spacecraft Radiation is the only means to transfer

heat into and out of the satellite


Conduction

Heat flows by conduction through an object from the hot end to the cool end.

Spacecraft use conduction to remove heat from hot components.


Convection

Boiling water on a stove shows how convection moves heat through a fluid from the fluid near a hot surface to the cooler fluid on top.

Special devices on spacecraft use convection to remove heat from hot components


Radiation

Radiation is the only way to transfer heat out of the spacecraft because there is no liquid (air) to tranfer it via conduction.


Micrometeoroids and Space Junk

Natural Sources 20,000 tons of debris bombard Earth annually Vary in size from dust-like particles to large

asteroids

Artificial Sources Old satellites, parts of launch vehicles Tools, paint chips

Small Objects at High Speed (lots of momentum)


NEWS LAST NIGHT

What was the boom and flash in the skies last night?


Micrometeoroids and Space Junk

Cerise spacecraft lost a 6-foot boom from a collision with a piece of space junk

Crater in Space Shuttle Challenger’s window from collision with a paint chip


http://orbitaldebris.jsc.nasa.gov/photogallery/beehives.html#leo

http://orbitaldebris.jsc.nasa.gov/photogallery/beehives.html#leo


The Radiation Environment

Primarily from the Sun Mainly visible light and infrared (heat) X-rays and gamma radiation also present

Impact: Photons good for generating electrical power (solar

panels) Heat radiation (infrared) heats spacecraft Ultra-violet radiation can damage electronic

equipment, disrupt communications Photons striking surfaces can impart a force: solar

pressure


Solar Max Spacecraft

Spacecraft with large surface areas, such as solar panels, must correct for the pressure from solar radiation that may change their altitude


Charged Particles

Sources: Solar wind and flares Galactic cosmic rays

(solar wind from distant stars, remnants of Big Bang)

Van Allen Radiation Belts—regions of the Earth’s magnetic field

Van Allen Radiation Belts


Charged Particles (cont’d) Effects on Spacecraft

Charging Similar: cross a carpeted room and touch a door knob Rapid and unpredicted discharges can “fry” equipment

Sputtering Wearing down of spacecraft surfaces by continual

bombardment of particles Similar to sandblasting

Single Event Phenomenon (SEP) Electronic disruptions caused by deeply penetrating

charged particles “Bit-flip”: changing of a zero to a one or vice-versa


Living and Working in Space

Free Fall Radiation and Charged Particles Mental and Emotional Effects


Living and Working in Space

Free Fall Fluid shift

Fluids equalize (no longer concentrated in lower body)

Edema Dehydration Increased heart rate


Space Environment Effects on Humans

Free fall (cont’d) Motion sickness

Reduced load on weight-bearing tissues Decalcifies bones Reduces production

of blood cells Weakens bones and

muscles


Space Environment Effects on Humans (cont’d)

Radiation and Charged Particles Measurement of exposure

Dosages of radiation add up over time

Cumulative effects over time Prolonged exposure to radiation means higher

dosages Total effect depends on biological impact of the

dosages


Space Environment Effects on Humans (cont’d)

Mental and Emotional Effects Excessive workload Isolation, loneliness,

depression Careful screening

and busy schedules help prevent problems.


Summary The Cosmic Perspective

Where is Space? The Solar System The Cosmos

The Space Environment and Spacecraft Challenges of the Space Environment Gravity Atmosphere Vacuum Micrometeoroids and Space Junk The Radiation Environment Charged Particles

Living and Working in Space Hazards to Humans in Space Free Fall Radiation and Charged Particles Mental and Emotional Effects


Next

Now that you know about the conditions you and your spacecraft can encounter in space, we’re ready to start discussing the basics of orbital motion.

the space environment

Documents

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space environmentpacking

space environment section

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electromagnetic radiation

solar systemthe cosmoscosmos

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