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I go a lot further again

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hey babe

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welcome to this edition of NASA images

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i'm lynn Bondurant during this show

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we're focusing on historic NASA film

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showing electric rockets and more recent

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videotape showing how we may someday

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explore Mars first let's go back to 1965

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to see most of the film electric

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propulsion though made in the mid 1960s

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much of the film is still current a

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concept showing how electric Rockets

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could be used to fly space travelers to

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Mars is included imagine for a moment

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that this is the period of the 1970s and

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1980s a period of amazing explorations

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imagine that the distant planet Jupiter

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is to be investigated scientifically by

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a spacecraft that will fly close by at

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the correct place in its orbit it's

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conventional chemical engines are fired

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to accelerate it to the velocity needed

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to get to Jupiter imagine also that nine

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and a half months later a craft with

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advanced engines is launched it slowly

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accelerates until it escapes Earth's

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gravity one year after the conventional

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craft started of course the first craft

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is well on its way since leaving Earth

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it has been coasting and it's velocity

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has continuously decreased but constant

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thrust is applied to the second craft

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for six months which continuously

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increases its velocity even though it

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escaped earth

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a year later it reaches Jupiter about

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eight months ahead of the conventional

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craft and carries three times the

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what could make this possible electric

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propulsion as used in the hypothetical

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second spacecraft and it is now under

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active research and development since

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the advent of the Space Age the roaring

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flaming spectacle of the chemically

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fueled rocket has become a common

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occurrence carrying space vehicles into

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Earth orbit and deep space the weight of

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such a payload is extremely small

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compared to the liftoff weight of the

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entire rocket because a chemical booster

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can put only 2 to 3% of its weight into

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orbit this lifting ratio cannot be

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improved significantly yet today the

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chemical rocket is the only means of

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launching a payload from Earth once the

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vehicle is in Earth orbit a chemical

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engine can send only about 1/3 of its

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orbital weight to the moon or the near

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planets two-thirds is fuel and engines

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the craft quickly burns the fuel of its

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final stage to accelerate the payload to

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a high velocity which then coasts the

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rest of the way this coasting flight

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takes considerable time to cover large

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distances but many deep space missions

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can be performed better by applying

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small amounts of thrust during most or

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over long distances

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this continuous thrusting will

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accelerate spacecraft to very high

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velocities and shorten overall travel

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time when perfected electric propulsion

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will provide the continuous thrust

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needed to reduce travel time to distant

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points and will use fuel so effectively

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that a larger fraction of the Earth

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orbit weight will be delivered as useful

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payload if the goals for electric

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propulsion are achieved the entire solar

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system will be open to versatile

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exploration the most difficult space

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mission of this decade will be the

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landing of men on the moon and getting

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them back safely man in space must be

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transported in the shortest possible

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time today only an all chemical

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propulsion system can do this job of

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moon exploration but what lies beyond to

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establish and maintain a scientific base

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on the moon will require the delivery of

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large amounts of supplies and equipment

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a very expensive operation to send large

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manned spacecraft and unmanned probes to

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Mars and Beyond will require the

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propelling of very large payloads over

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great distances just to lift these

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heavier payloads into deep space with

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all chemical systems will require either

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building bigger and bigger launch

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vehicles or launching several vehicles

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into Earth orbit carrying engines and

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fuel and then assembling them to provide

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the propulsion needed both alternatives

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are extremely expensive so a propulsion

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system is needed that will use fuel more

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in a propulsion system fuel economy can

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be increased by speeding up the exhaust

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gases in chemical rockets the exhaust

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velocity is limited by the temperatures

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so methods other than combustion have to

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one way is to use the heat of a nuclear

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reactor to increase the exhaust velocity

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of a light gas such as hydrogen this

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velocity is about 2 and 1/2 times that

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therefore nuclear rockets will use fuel

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two and a half times as effectively as

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chemical rockets another way to increase

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exhaust velocity is to use electrical

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energy instead of heat to accelerate the

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propellant gas up to 20 times or more

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than in chemical rockets these high

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exhaust velocities in the electric

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engine increase the effectiveness of the

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fuel 20 times and more as well resulting

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in much more work per pound of fuel with

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this high fuel effectiveness and with

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the ability to apply continuous thrust

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the electric engine is a promising

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candidate for true space propulsion it

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cannot be used as a launch engine but

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once in space it can take over after the

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high thrust chemical booster has given

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the space vehicle sufficient velocity to

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overcome the main effects of gravity the

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electric engine is started this small

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thrust applied intermittently or

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continuously for months or years will

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the effect of a very small thrust

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applied over a long time is the same as

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a very large thrust applied for a very

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short time thrust multiplied by the time

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it is applied is called total impulse a

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million pounds of thrust applied for 30

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seconds will deliver 30 million pound

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seconds of total impulse the same as a

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pound of thrust applied for 30 million

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seconds which is roughly a year each

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flight in space requires a certain total

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impulse the goal of deep space

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propulsion is to use the least amount of

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fuel for a given total impulse in space

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propulsion fuel economy of a rocket

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engine is discussed in terms of specific

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impulse which is defined as the total

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the higher the specific impulse the

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longer in seconds one pound of fuel will

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deliver one pound of thrust for

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convenience specific impulse is

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expressed in seconds chemical rockets

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are limited to specific impulses of

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about 450 seconds and relatively little

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improvement can be expected solid fuel

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nuclear rockets are expected to deliver

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up to about 1000 seconds of specific

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impulse electric engines however are now

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operating at specific impulses from

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around 800 to 10,000 seconds and higher

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the higher the specific impulse

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the higher the fuel economy but

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unfortunately as specific impulse

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increases for the same thrust the

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electric power needs increase and

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powerplant

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weight goes up even more so an optimum

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value must be bound for each mission but

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even with this compromise for many

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manned and unmanned interplanetary

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missions the electric engine appears to

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be the propulsion system to deliver

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significant payloads within a reasonable

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time for missions to Pluto for example

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the electric engine is the only device

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that can deliver any payload at all the

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power source for electric engines will

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be either a nuclear reactor or solar

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cells or heat concentrators depending

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upon how much power is needed waste heat

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is rejected to space by a radiator heat

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from the power source drives an

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electrical generator the electrical

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power is conditioned and controlled to

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provide the necessary voltages and

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currents the typical propulsion system

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also includes propellant storage and

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feed devices which lead to the engine

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itself three types of electric engines

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are under development they differ

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primarily in the way the propellant is

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accelerated the electro thermal engine

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uses an electric arc or resistance

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element to heat a propellant gas to a

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very high temperature which produces a

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high exhaust velocity specific impulses

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from 802 in excess of 2,500 seconds are

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possible with these engines the electro

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thermal engines have demonstrated good

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performance in vacuum chamber tests

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however laboratory work must continue in

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order

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electromagnetic engines a fast-moving

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ionized gas is generated and used as the

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propellant this gas is a plasma of ions

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and electrons electric and magnetic

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fields then speed up the charged

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particles to much higher exhaust

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velocities a specific impulse range of

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800 to an excess of 10,000 seconds

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appears to be possible these

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electromagnetic devices are the least

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developed at this time however there are

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many promising designs under laboratory

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investigation in the third type the

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electrostatic or ion engine cesium or

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mercury fuel is ionized and the

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resulting electrons removed the ions

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being positively charged are accelerated

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to very high velocities by a high

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negative voltage electrode these engines

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will operate at specific impulses from

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electrostatic ion engines are the most

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advanced electric type but much work

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remains to develop larger more efficient

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though work on electric engines has been

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underway only since 1959 great progress

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has been made in government and

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contractor laboratories thrust levels

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approaching a pound have already been

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obtained yet enormous strides must still

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be taken before larger reliable engines

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are available goals for electric systems

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include achieving power supply weights

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of less than 40 and an ultimate goal of

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20 pounds per kilowatt with lifetimes of

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more than 10,000 hours development of

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the engines themselves strives for

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smaller weight and size per unit thrust

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and higher overall effectiveness

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eventually the entire engine system must

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operate continuously for up to four

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years by grouping engines together as

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building blocks power levels up to 40

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megawatts and total thrusts of over 450

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pounds may be obtained in addition to

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this laboratory work electric engines

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must be flight tested space conditions

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cannot be totally simulated even in

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these advanced vacuum chambers and there

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may be influential environmental factors

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in space unknown at this time small

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electric engines already being developed

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may perform early missions the first

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application may be to control a

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synchronous communication satellite

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these engines can deliver small accurate

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bits of thrust for months or years using

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only small amounts of fuel solar cells

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will furnish the power another solar

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powered application could be the raising

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of an advanced communication satellite

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from a low Earth orbit to its final

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solar-powered electric engines may also

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be used to slowly spiral out a

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scientific satellite to make a detailed

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study of the Van Allen belt flight tests

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and early missions will provide data

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that will help perfect the larger

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electric engines needed for more

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ambitious projects large electric

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propulsion systems

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when perfected they take large amounts

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of supplies and equipment to the moon

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and do it much cheaper than all chemical

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systems chemically propelled boosters

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will place the freight into Earth orbit

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the spacecraft may incorporate a small

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chemical engine and electrically

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propelled lunar freighter will

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rendezvous with the craft take it to the

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vicinity of the moon and place it in a

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the chemical stage will lower the

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freight loaded craft to the lunar

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while the electrically driven freighter

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returns to Earth orbit for another load

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it will continue to shuttle back and

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forth with periodic fuel replacement as

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long as its power supply lasts of course

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the electric freighter will take longer

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to get to the moon but for most Freight

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the longer travel time is not an

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important consideration for the same

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amount of freight this system will need

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far fewer expensive earth launch

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boosters than all chemical system would

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on small vehicle missions to the near

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planets Mars and Venus electric engines

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can deliver much more payload by taking

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a slightly longer time a three-stage

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chemical rocket now being studied could

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get a 2,500 pound payload into an orbit

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around Mars in about 210 days and

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electrically propel spacecraft

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substituted for the third stage could do

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as well in the same time but by using a

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higher specific impulse engine and

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taking only 40 more days it can deliver

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twice the payload to those planets

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beyond Mars and Venus electric

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propulsion gives both the payload and

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time advantage it appears to be the most

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promising means of sending scientific

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probes from Earth orbit into the

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asteroid belt beyond Mars to Jupiter and

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farther a greater the distance the

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greater the advantages of electric

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propulsion looking toward the day when

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large power supplies from 20 to 40

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megawatts and large engines of proven

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reliability are available scientists

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have developed a concept for a manned

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Mars expedition with electrically

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propelled vehicles the concept suggests

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the expedition will consist of five

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spaceships which will be assembled in a

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the completed ships will each weigh 360

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tons and will carry a payload of 40 tons

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at one end of the vehicle

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there will be a 40 megawatt nuclear

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power supply next will be power

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converter equipment there also will be

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radiators to give off waste heat and

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cesium fuel tanks at the other end will

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be a three-man crew compartment there

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will be a total of 15 men to perform all

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the mission objectives three of the

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ships will carry piggyback Mars landing

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vehicles while the other two will carry

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extra fuel for the return to earth five

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00:19:47,509 --> 00:19:44,399
vehicles will be used for safety

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purposes if one or more failed the men

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would be transferred to the other ships

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to continue the flight or return to

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Earth after checkout and placing the

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flight crew aboard the electric engines

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would spiral them continuously for 56

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00:20:05,210 --> 00:20:00,960
days until they escape the Earth's

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gravity then they would enter a transfer

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orbit around the Sun traveling toward

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Mars the ships would take 148 days to

359
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make the trip to the vicinity of the

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once near Mars they would spiral into a

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low orbit this would take an additional

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21 days once in this orbit one of the

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piggyback chemical vehicles would go

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down to the surface without men to land

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equipment then one manned craft would

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land to explore the surface after 29

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days the party would board the landing

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craft and rejoin the ships then the

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landing craft would be abandoned and the

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fuel equalized between ships for the

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return trip they would reverse their

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original flight path and head back to a

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low Earth orbit this would take another

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318 days making a total of five hundred

375
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seventy-two days for the round-trip by

376
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applying thrust continuously over vast

377
00:21:23,390 --> 00:21:14,930
distances travel time will be greatly

378
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he will will be used so effectively that

379
00:21:30,390 --> 00:21:28,150
a much bigger weight fraction of the

380
00:21:36,720 --> 00:21:30,400
space vehicle will be devoted to useful

381
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payload reduce travel time to the

382
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distant planets larger useful payloads

383
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these are the goals of electric

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propulsion which will allow numerous

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missions to be carried out that would

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otherwise be impractical or impossible

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our next film is more recent from 1987

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it's also about exploring Mars Mars

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00:22:08,250 --> 00:22:05,650
commonly referred to as the red planet

390
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is one of our closest neighbors beyond

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the moon it has qualities that make it a

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potentially habitable outpost before all

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Martian exploration ended in November

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1982 a handful of probes had made the

395
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year-long journey Viking ones orbiter

396
00:22:29,139 --> 00:22:26,800
completed nearly 1500 picture-taking

397
00:22:31,329 --> 00:22:29,149
trips around the planet

398
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while it's Lander studied samples and

399
00:22:36,279 --> 00:22:33,799
returned to views from the surface as a

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00:22:38,739 --> 00:22:36,289
result Mars is well met but many

401
00:22:40,989 --> 00:22:38,749
questions remain so researchers are

402
00:22:43,810 --> 00:22:40,999
designing systems to explore the varied

403
00:22:47,349 --> 00:22:43,820
Martian geography in anticipation of a

404
00:22:49,659 --> 00:22:47,359
return mission on calm sunny mornings

405
00:22:51,519 --> 00:22:49,669
Jim Burke can often be found flying this

406
00:22:52,930 --> 00:22:51,529
lightweight solar balloon in the

407
00:22:56,440 --> 00:22:52,940
courtyard at NASA's Jet Propulsion

408
00:22:58,329 --> 00:22:56,450
Laboratory in Pasadena California mr.

409
00:23:00,459 --> 00:22:58,339
Burke views his study as an important

410
00:23:02,529 --> 00:23:00,469
stepping stone to a larger goal in

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gathering more precise information about

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the red planet NOW the Martian

413
00:23:11,709 --> 00:23:09,499
atmosphere is carbon dioxide and if you

414
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put a black balloon that's light enough

415
00:23:17,320 --> 00:23:14,389
with a light enough payload into that

416
00:23:19,719 --> 00:23:17,330
atmosphere the sun shining on the black

417
00:23:21,700 --> 00:23:19,729
balloon will warm it up like the heat

418
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inside a parked car with the windows

419
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shut and it gets hot enough inside to

420
00:23:32,139 --> 00:23:29,570
become a hot air balloon scientists

421
00:23:34,450 --> 00:23:32,149
students and engineers from JPL and the

422
00:23:36,430 --> 00:23:34,460
California Institute of Technology have

423
00:23:38,769 --> 00:23:36,440
taken the concept a step further by

424
00:23:41,079 --> 00:23:38,779
testing the feasibility of this 30 foot

425
00:23:44,649 --> 00:23:41,089
diameter solar balloon that might be

426
00:23:46,690 --> 00:23:44,659
used to study Mars in theory the device

427
00:23:48,759 --> 00:23:46,700
could be blown around by local Martian

428
00:23:50,979 --> 00:23:48,769
winds during the day to collect data and

429
00:23:53,649 --> 00:23:50,989
take pictures at night it would cool

430
00:23:55,539 --> 00:23:53,659
down lose buoyancy and lower itself to

431
00:23:58,930 --> 00:23:55,549
the ground to survey the planet's

432
00:24:00,459 --> 00:23:58,940
surface the small clear balloon holds

433
00:24:01,959 --> 00:24:00,469
the larger one off the ground at night

434
00:24:04,119 --> 00:24:01,969
so it won't get damaged

435
00:24:06,010 --> 00:24:04,129
there are many regions of Mars that

436
00:24:09,450 --> 00:24:06,020
could be explored this way

437
00:24:13,180 --> 00:24:09,460
to Gymboree one very interesting

438
00:24:15,610 --> 00:24:13,190
possibility is to put the balloon in the

439
00:24:17,800 --> 00:24:15,620
atmosphere get it inflated operating up

440
00:24:21,550 --> 00:24:17,810
in the polar regions and let the

441
00:24:25,180 --> 00:24:21,560
circumpolar winds drift it down across

442
00:24:27,520 --> 00:24:25,190
the polar cap over the layered terrain

443
00:24:29,620 --> 00:24:27,530
which is in the canyons that spiral out

444
00:24:33,370 --> 00:24:29,630
from the polar cap then across the

445
00:24:35,770 --> 00:24:33,380
immense dune fields that surround the

446
00:24:38,860 --> 00:24:35,780
polar caps and on downward into

447
00:24:41,320 --> 00:24:38,870
temperate latitudes on Mars to remotely

448
00:24:43,480 --> 00:24:41,330
explore the surface of Mars a number of

449
00:24:46,060 --> 00:24:43,490
devices have been investigated they

450
00:24:48,490 --> 00:24:46,070
include early roving vehicle prototypes

451
00:24:51,730 --> 00:24:48,500
designed to crawl or wheel their way

452
00:24:53,980 --> 00:24:51,740
across alien terrain Rovers continue to

453
00:24:58,090 --> 00:24:53,990
be designed today based on some of these

454
00:25:00,400 --> 00:24:58,100
models University of Arizona's lunar and

455
00:25:02,170 --> 00:25:00,410
planetary labs graduate students and

456
00:25:05,260 --> 00:25:02,180
faculty have recently built this

457
00:25:06,060 --> 00:25:05,270
gigantic two-wheeled prototype Mars

458
00:25:08,470 --> 00:25:06,070
rover

459
00:25:10,840 --> 00:25:08,480
another vehicle being developed as this

460
00:25:13,450 --> 00:25:10,850
robotic six wheeled version which is

461
00:25:15,610 --> 00:25:13,460
JPL's latest testbed for understanding

462
00:25:18,010 --> 00:25:15,620
the control and vision systems needed

463
00:25:19,870 --> 00:25:18,020
for a Mars mission according to Brian

464
00:25:22,690 --> 00:25:19,880
Wilcox of the robotics and tella

465
00:25:24,610 --> 00:25:22,700
operators Research Group at JPL sending

466
00:25:27,070 --> 00:25:24,620
commands to a rover on Mars would be

467
00:25:29,500 --> 00:25:27,080
difficult because of the 10 to 40 minute

468
00:25:31,660 --> 00:25:29,510
round-trip delay you can't just sit

469
00:25:34,090 --> 00:25:31,670
there and steer in your armchair from a

470
00:25:36,190 --> 00:25:34,100
TV monitor and make the vehicle do

471
00:25:37,750 --> 00:25:36,200
useful things because of this long speed

472
00:25:40,870 --> 00:25:37,760
of light delay so we've identified

473
00:25:43,720 --> 00:25:40,880
several techniques to maneuver a vehicle

474
00:25:46,690 --> 00:25:43,730
on Mars in such a way that you can go

475
00:25:49,270 --> 00:25:46,700
useful distances in a day in spite of

476
00:25:51,490 --> 00:25:49,280
the fact that the humans are this long

477
00:26:09,550 --> 00:25:51,500
speed of light delay remove from the

478
00:26:14,930 --> 00:26:12,830
the rugged vehicle has two TV cameras

479
00:26:17,600 --> 00:26:14,940
for eyes and is capable of climbing

480
00:26:19,880 --> 00:26:17,610
objects 1/3 taller than its wheel height

481
00:26:22,310 --> 00:26:19,890
the proposed mission vehicle would have

482
00:26:30,430 --> 00:26:22,320
robotic arms to make measurements and

483
00:26:35,749 --> 00:26:33,289
using Rovers onboard vision system

484
00:26:37,580 --> 00:26:35,759
scientists can freeze three-dimensional

485
00:26:40,190 --> 00:26:37,590
images from its pair of television

486
00:26:42,499 --> 00:26:40,200
cameras they can then designate the

487
00:26:44,629 --> 00:26:42,509
pathway to follow continually updating

488
00:26:48,070 --> 00:26:44,639
commands from Earth so that the rover is

489
00:26:50,810 --> 00:26:48,080
able to avoid obstacles and hazards as

490
00:26:52,430 --> 00:26:50,820
more sophisticated visual systems are

491
00:26:54,560 --> 00:26:52,440
developed greater artificial

492
00:26:57,200 --> 00:26:54,570
intelligence can help the rover find its

493
00:26:59,539 --> 00:26:57,210
own way if given high-resolution imagery

494
00:27:01,700 --> 00:26:59,549
of the Martian surface and a list of

495
00:27:05,060 --> 00:27:01,710
targeted regions designated by

496
00:27:06,950 --> 00:27:05,070
earthbound scientists the hope is to

497
00:27:09,409 --> 00:27:06,960
someday send a manned mission to Mars

498
00:27:11,840 --> 00:27:09,419
but a more detailed study of the planet

499
00:27:14,269 --> 00:27:11,850
is necessary first and these pioneering

500
00:27:17,330 --> 00:27:14,279
steps can be made by roving vehicles and

501
00:27:20,299 --> 00:27:17,340
balloons again Brian Wilcox if you

502
00:27:22,629 --> 00:27:20,309
imagine an expedition Lewis and Clark

503
00:27:25,609 --> 00:27:22,639
trying to survey the Louisiana Purchase

504
00:27:27,289 --> 00:27:25,619
they've basically made one track across

505
00:27:30,379 --> 00:27:27,299
a very small fraction of the land

506
00:27:33,680 --> 00:27:30,389
surface of the earth took them years to

507
00:27:35,299 --> 00:27:33,690
do it and yet they found incredible

508
00:27:38,090 --> 00:27:35,309
things all along the way we could

509
00:27:41,930 --> 00:27:38,100
certainly have a dozen Rover missions

510
00:27:45,919 --> 00:27:41,940
which yielded equally interesting

511
00:27:48,950 --> 00:27:45,929
results the exploration of Mars sending

512
00:27:51,800 --> 00:27:48,960
unmanned vehicles as pathfinders for the

513
00:27:57,420 --> 00:27:54,270
that's all we have for this edition of

514
00:27:59,640 --> 00:27:57,430
NASA images but before we go let me

515
00:28:02,190 --> 00:27:59,650
remind you that you're cordially invited

516
00:28:04,380 --> 00:28:02,200
to see the displays here at the Visitor

517
00:28:07,080 --> 00:28:04,390
Center at the NASA Lewis Research Center

518
00:28:09,660 --> 00:28:07,090
we're located near Hopkins International