EAPS 106|95 Exam 3 Questions
How we can simulate gravity on a spacecraft. - ✔ ✔ By rotating the spacecraft,
generating a centrifugal force that simulates gravity.
"Down" always points outwards from the center of rotation
How we know that the Oort Cloud is a sphere. - ✔ ✔ Long period comets
come form the oort cloud, a spherical collection of billions of small icy objects. We
know it's a sphere because long period comets come at us from all directions.
Why are there more impact cheaters on the moon today than on the earth? - ✔
✔ The moon has no erosional processes to erase old impact craters
Why comets are referred to as dirty ice balls. - ✔ ✔ Because they are mixture
of ice and rock
Why do iron meteorites exist? - ✔ ✔ From impacts that break up big asteroids
that have differentiated into an iron core and a stony mantle.
Why fighting smaller fires lead to much bigger ones. - ✔ ✔ If there are no
smaller fires to remove the underbrush and fuel that builds up, they can lead to
massive fires due to the built up fuel. In typical forests, every year without fire
adds the equivalent of 300 gallons of gasoline per acre.
Why fire retardants dropped from air tankers are colored red. - ✔ ✔ Dyed so
that they can see where they've already dropped
Why Haley's comet is the most famous of all comets. - ✔ ✔ Because it is a
short-period comet that comes into view about once in a lifetime (~75 years)
Only short-period comet visible to the naked eye
Last appeared in 1986 will next appear in 2061
Its passage has been recorded since at least 240 B.C.E
,Why impact craters are almost always round. - ✔ ✔ Impact craters are almost
always round because the impact shock wave travels outward equally in all
directions regardless of the impact angle.
Why is Mars the most explored planet? - ✔ ✔ Extraterrestrial life
Why Mars is the most explored planet. - ✔ ✔ It holds the greatest chance of
finding evidence of past or present extraterrestrial life
Why the highest percentage of human ignited fires occur in the southeastern U.S.
- ✔ ✔ The southeast is hot and densely populated.
Why the International Astronomical Union (IAU) did not want Pluto to be a
planet. - ✔ ✔ "If pluto could stay, you logically have to let the number of
planets rise to 24 or 25, with the possibility of 50 or 100 within the next decade.
Do we want schoolchildren to have to remember so many? no, we want to keep
the numbers low." -Gareth Williams, associate director of the IAU's Minor Planet
Center.
In general, how do planetary scientists classify Pluto? - ✔ ✔ a planet
That comet dust jets do not turn on and off with the comet's sunrise and sunset. -
✔ ✔ Jets are unrelated to sunrise and sunset debris
Turn on Sporadically and last short time periods. They can turn on and off in 10s
of minutes even though the rotation time is much larger
Not sure what initiates them, but could be landslides pushing debris into gas jets
That cryovolcanoes on Saturn's moon Enceladus dumps material from its
subsurface ocean into Saturn's E-ring. - ✔ ✔ The erupted water freezes and
feeds Saturn's E-ring. Subsurface ocean revealed by water geysers
That planet size also matters for a planet to be considered potentially habitable. -
✔ ✔ Planet size can affect the atmosphere it can hold, too small and can't
hold enough, too big and it'll hold things like hydrogen. Needs to be relatively
Earth sized
, .8 - 1.5 Earth's radius
That there are more estimated Earth-like planets than grains of sand on Earth. -
✔ ✔ For every grain of sand on earth, there are 50 Earth-like planets.
Estimated 500 stars for every grain of sand on Earth, 500 times 8x10^18
That there are other objects of similar size to Pluto in the Kuiper Belt. - ✔ ✔
Yes there is, started to discover other objects in the Kuiper belt in the 1990's
with better telescopes. Eris, about the same size as Pluto, is named for the Greek
goddess of chaos, strife, and discord, appropriate since it kicked off the debate
about the definition of a planet and the demotion of Pluto.
The advantage that a helitankers have over air tankers. - ✔ ✔ Air tankers
- with wheels have to return to some airport to refill their tanks, although
seaplanes are able to refill in lakes or reservoirs
- Have a higher capacity of water or fire retardant
Helitankers
- can refill on the go from a pond, lake, pool, etc. - smaller bodies of water than
planes
- can perform more targeted drops
- can also carry water cannons similar to fire trucks
- Shorter range to drop
- Smaller capacity
the best strategy to survive an extinction level size asteroid or comet on an
intercept course with Earth. - ✔ ✔ The best collision avoidance strategies
involve deflection.
Kinetic impact: crash a heavy spacecraft into it to alter trajectory.
Spacecraft propulsion: create a small sustained thrust to alter trajectory.
How we can simulate gravity on a spacecraft. - ✔ ✔ By rotating the spacecraft,
generating a centrifugal force that simulates gravity.
"Down" always points outwards from the center of rotation
How we know that the Oort Cloud is a sphere. - ✔ ✔ Long period comets
come form the oort cloud, a spherical collection of billions of small icy objects. We
know it's a sphere because long period comets come at us from all directions.
Why are there more impact cheaters on the moon today than on the earth? - ✔
✔ The moon has no erosional processes to erase old impact craters
Why comets are referred to as dirty ice balls. - ✔ ✔ Because they are mixture
of ice and rock
Why do iron meteorites exist? - ✔ ✔ From impacts that break up big asteroids
that have differentiated into an iron core and a stony mantle.
Why fighting smaller fires lead to much bigger ones. - ✔ ✔ If there are no
smaller fires to remove the underbrush and fuel that builds up, they can lead to
massive fires due to the built up fuel. In typical forests, every year without fire
adds the equivalent of 300 gallons of gasoline per acre.
Why fire retardants dropped from air tankers are colored red. - ✔ ✔ Dyed so
that they can see where they've already dropped
Why Haley's comet is the most famous of all comets. - ✔ ✔ Because it is a
short-period comet that comes into view about once in a lifetime (~75 years)
Only short-period comet visible to the naked eye
Last appeared in 1986 will next appear in 2061
Its passage has been recorded since at least 240 B.C.E
,Why impact craters are almost always round. - ✔ ✔ Impact craters are almost
always round because the impact shock wave travels outward equally in all
directions regardless of the impact angle.
Why is Mars the most explored planet? - ✔ ✔ Extraterrestrial life
Why Mars is the most explored planet. - ✔ ✔ It holds the greatest chance of
finding evidence of past or present extraterrestrial life
Why the highest percentage of human ignited fires occur in the southeastern U.S.
- ✔ ✔ The southeast is hot and densely populated.
Why the International Astronomical Union (IAU) did not want Pluto to be a
planet. - ✔ ✔ "If pluto could stay, you logically have to let the number of
planets rise to 24 or 25, with the possibility of 50 or 100 within the next decade.
Do we want schoolchildren to have to remember so many? no, we want to keep
the numbers low." -Gareth Williams, associate director of the IAU's Minor Planet
Center.
In general, how do planetary scientists classify Pluto? - ✔ ✔ a planet
That comet dust jets do not turn on and off with the comet's sunrise and sunset. -
✔ ✔ Jets are unrelated to sunrise and sunset debris
Turn on Sporadically and last short time periods. They can turn on and off in 10s
of minutes even though the rotation time is much larger
Not sure what initiates them, but could be landslides pushing debris into gas jets
That cryovolcanoes on Saturn's moon Enceladus dumps material from its
subsurface ocean into Saturn's E-ring. - ✔ ✔ The erupted water freezes and
feeds Saturn's E-ring. Subsurface ocean revealed by water geysers
That planet size also matters for a planet to be considered potentially habitable. -
✔ ✔ Planet size can affect the atmosphere it can hold, too small and can't
hold enough, too big and it'll hold things like hydrogen. Needs to be relatively
Earth sized
, .8 - 1.5 Earth's radius
That there are more estimated Earth-like planets than grains of sand on Earth. -
✔ ✔ For every grain of sand on earth, there are 50 Earth-like planets.
Estimated 500 stars for every grain of sand on Earth, 500 times 8x10^18
That there are other objects of similar size to Pluto in the Kuiper Belt. - ✔ ✔
Yes there is, started to discover other objects in the Kuiper belt in the 1990's
with better telescopes. Eris, about the same size as Pluto, is named for the Greek
goddess of chaos, strife, and discord, appropriate since it kicked off the debate
about the definition of a planet and the demotion of Pluto.
The advantage that a helitankers have over air tankers. - ✔ ✔ Air tankers
- with wheels have to return to some airport to refill their tanks, although
seaplanes are able to refill in lakes or reservoirs
- Have a higher capacity of water or fire retardant
Helitankers
- can refill on the go from a pond, lake, pool, etc. - smaller bodies of water than
planes
- can perform more targeted drops
- can also carry water cannons similar to fire trucks
- Shorter range to drop
- Smaller capacity
the best strategy to survive an extinction level size asteroid or comet on an
intercept course with Earth. - ✔ ✔ The best collision avoidance strategies
involve deflection.
Kinetic impact: crash a heavy spacecraft into it to alter trajectory.
Spacecraft propulsion: create a small sustained thrust to alter trajectory.
