JUICE BOX ON JUPITER
------------------
John Pazmino
NYSkies Astronomy Inc
nyskies@nyskies.org
www.nyskies.org 2013 July 17
2013 August 1
Introduction
----------
Intrepid Museum on Manhattan held its second annual Space Fest on
2013 July 25-28. This is a 'street fair' of space\related displays and
activities on the pier next to the Intrepid ship, sponsored by NASA
and space industries.
I went as a spectator in afternoon of Friday the 26th. I skipped
all of the other days and didn't study the program that closely. I
figured one afternoon was enough and it would also be my first look at
the newly rebuilt pavilion for Shuttle Enterprise.
Alert!
----
On Thursday the 25th Steve Kaye, NYSKies and earth science teacher,
called me at work. He was all jived up because he checked the Space
Fest program on Wednesday to sign up for a teacher's workshop for that
very Thursday. He called Intrepid and learned that the event was moved
to Saturday, July 27th.
He could attend than but thought I should be alerted. He pushed me
to look at the new schedule on the Intrepid website and, if possible,
sign up for it. I did sign up via email and got the confirmation later
on Thursday afternoon by email reply. The event was free but
registration was required in advance.
I printed out the program from Intrepid's website. The activities
looked really interesting. Intrepid over the last several years, since
it acquired Enterprise and took a more lively concern for space, along
with air and sea, in its theme. It runs from time to time mature and
worthy programs for the public and educators in the space sciences.
One is the occasional Astronomy Night where NYSkies is engaged to
conduct clearsky starviewing and be a resource crew for inquiries.
Chicago City Limits
-----------------
Intrepid Museum is built into and around a retired World War II
aircraft carrier. It is moored at pier 86 on Hudson River in a
district sometimes called 'Chicago city limits' for its remoteness
from the midline of Manhattan.
It was in its early years tough to reach with scanty bus service
nearby. In the last ten years service was beefed up by extending
certain crosstown routes into the area. This was partly for the
traffic at Intrepid and other riverfront attractions and partly for
the new wave of residence towers sprouting on the far west side of
Manhattan. There is soon, maybe by fall 2013, a new thrutown route
with stops every couple piers all along Chicago City Limits.
With the growth of riverfront activity in the 21st century the
entire shore is improved with segregation of foot and road traffic,
good -- star-friendly -- illumination, benches, lookout alcoves,
flowers and trees. Street furniture has a nautical motif recalling the
era when this was part of the City's seafaring industry.
I note that on Hudson River, also called North River from Battery
Park, the south end of Manhattan, to 59th Street, the piers are
numbered 40 higher than the streets they line up with. Intrepid is at
pier 86 at 46th Street. Streets are not numbered regularly until pier
40 at Houston Street or 1st Street. That's how the offset came about.
Arrival
------
I left home in Brooklyn a little before 7 AM and took a local bus
and train to Times Square. There I caught the M42 bus to Hudson River.
Its terminal is at Pier 83, the Circle Line cruise ships. Because 42nd
St is a very busy corridor at all hours the bus runs every couple
minutes. On the other hand the speed is languid for the dense road
traffic. The bus is trapped in this traffic so that at times several
M42 vehicles crawl along per block!
The workshop, the exact title varied among the Intrepid
litterature, began with muster-up at 8:30 AM EDST to be let in as a
group well before the opening hour of the Museum. When I arrived doors
just opened and I entrained with the crowd to do security check and
collect a visitor badge and program.
Action started at 9:00 AM EDST with a reception and breakfast
under, yes, UNDER, the Enterprise. The Shuttle is mounted some three
meters off of the floor to allow free circulation of visitors around
and under it. It is tilted slightly forward, to simulate a landing,
and maybe to let visitors see more into the cockpit from a viewing
platform at the Shuttle's nose.
Enterprise
--------
Enterprise was housed at since July 2012 in an inflated bubble
structure intended to be temporary while funds and construction of a
permanent hall can begin. In October 2012 hurricane Sandy tore the
bubble to shreds! The Shuttle was quickly saved from harm by tarps but
minor injury was taken by the tail fin. This was repaired on site by
the Museum's aircraft restoration team.
A new and more substantial house was started in spring 2013, which
opened on July 10th. I was going to see it then but I could not break
away from an astronomy conference on the same day, the 'Inspiration of
astronomical phenomena' at the American Museum of Natural History.
This Shuttle was at first ridiculed as a 'fake' or 'model', but it
was a real flying machine! It never reached outer space but was used
in atmospheric tests to test and refine the Shuttle design.When the
Shuttles were first planned, this first one was named 'Constitution'.
From the mania over the Star Trek space show it was renamed
'Enterprise'.
During the selection of sites to display the retired Shuttles in
2010, New York was widely considered a joke, with no good reason to be
honored with a Shuttle. Several other towns 'deserved' one far more
than the City.
At first the crafts Endeavor, Discovery, Atlantis were placed on
the East Coast, with Enterprise on the West Coast. But that put all
space-flying machines on one side of the country. For sure Smithsonian
needed a space-flying vehicle, so did Florida at Cape kennedy.
Endeavor and Enterprise were swopped so the former is in Los Angeles.
Smithsonian already had Enterprise and was picked to house
Discovery. Easy solution: Give Discovery to Washington and move its
Enterprise to New York!
Some other towns bitched and whined! Well, too damn bad. In the
due and proper process for allocating the Shuttles, it was patently
obvious that of all the candidate locations, New York has far and away
the most wisely and worthy astronomy and spacefaring population.
When I told Intrepid I'll be there for Space Fest it offered me a
visitor pass to save me the admission. This I picked up before
entering the Space Fest on that Friday the 26th. After taking in Space
Fest I went to the ship's flight deck with the pass to say 'hello' to
Enterprise.
Soyuz
---
Also in the Shuttle house is a new and unique spacecraft, a
genuine Soviet Soyuz capsule! It's the only Soviet spacecraft on
permanent display in the United States, altho many are exhibited else
where in the world, such as in Europe.
When a Soyuz capsule lands after a flight, it is usually discarded
as scrap. It isn't flight-worthy any more and the are few salvagable
parts. Some are cleaned up for exhibit. The capsule on return from
space has a rocket and other flight controls attached to it. This
section is separated destructively enter the atmosphere. The capsule,
a sphere about 2-1/2 meter diameter, is fitted for three cramped
riders, plus survival gear for sustained them until the recovery crew
on the ground can arrive.
The normal profile of a Soyuz flight is to rise to International
Space Station from Baikonur cosmodrome in Kazakhstan. It is the last
section of the rocket, the others falling back to burn up in the air.
With its propulsion module it chases after ISS, joins up with it, and
lets its riders crawl into ISS. The capsule stays attached as a
lifeboat in case of an evacuation. Altho as far as I know this never
happened, there were times when the ISS crew was sent into the Soyuz
to prepare for detach and descent, but the emergency passed and the
crew returned to ISS.
The lifeboat Soyuz is already docked to ISS when the arriving one
pulls in. This is the one used for the departure of the current ISS
crew. That is, capsules alternate, like relaying of a train or ferry
shuttle. Space tourist Greg Olsen, a New Jersey businessman, rode his
Soyuz capsule back to Earth but then bought the thing from Russia as a
souvenir! His money looked good and otherwise the craft would be
junked. He shipped the capsule to his office in New Jersey.
He donated it to the Intrepid Museum! On June 25 in 2013 it was
barged from New Jersey to the Intrepid and hoisted to the flight deck.
Some news media scrambled the story, stating the the capsule was found
and recovered from the bottom of Hudson River!
Our, America's!, Soyuz is in the Shuttle pavilion in a plexiglass
coral. You can inspect it close-up and look thru its hatch.
Audience
------
The people gathered at the entrance gate were educators, almost
all from schools in New York City. Intrepid advertised the workshop
thru its regular channels with the education sector, by which Mr kaye
learned about it.
All were young 20-40 folk, about 2/3 female. Many nationalities
and races were represented, a good cross-section of the City and
probably mirroring the mix of students in each person's school.
All were in casual dress, looking like students. Some were
students at a college, as gleaned from the banter within the crowd.
Altho none seemed specificly skilled in science, all knew enough to
appreciate the workshops and were ready and willing to use them for
furthering their teaching. A few seemed to have science as a personal
interest, like following space missions or visiting astronomy clubs.
The youth of the audience caused some curious episodes during the
workshop. At one session, 'Juice box on Jupiter' the chair mentioned
he was teaching astronomy for twelve years. This raised p gasps of
surprise from his audience. After that meeting I suggested he say he's
into astronomy for one Jovian year and added that I just completed
form my astronomy the FIFTH Jovian year.
At the other session Living in space' I attended the chair asked
some historical questions about the space program. The audience was
too young to personally go thru the Apollo, Cold War, the social
upheaval, civil rights. urban unrest era of the 1960s! To them, Russia
is just an other country sending immigrants to America to fill their
classrooms!!
Program
-----
After breakfast we watched a film in one corner of the Shuttle
house about the sick state of science, technology, engineering, and
math education in the United States. It was narrated by retired
astronaut Charles Camarda, All in the audience knew that, being mostly
science teachers.
Camarda later in the day gave a full-length presentation on the
same theme. This was part of the overall Space Fest program. Kaye went
to it but I passed it over.
Following this film we broke up into groups to do two out of about
a dozen concurrent workshops in various astronomy topics. While the
program was on the Intrepid website, and I brang my printout of it
with me, most picked out their workshops from the handed out programs.
I chose 'Juice box on Jupiter' and 'Living in space'. The ushers
steered the audience to the proper leader escort to the rooms else
where in the ship. Intrepid has many function rooms of assorted sizes
for its own events and for hire.
The 'Juice box on Jupiter' was a demonstration, easily replicated
in a school, for weight on different planets. 'Living in space' was a
discussion about conditions in outer space and how astronauts prepare
for and suffer from them. Both were chaired by excellently qualified
persons, the first form Intrepid and the second from Cradle of
Aviation on Long Island.
After the two workshops, each lasting about 45 minutes, we took
lunch in the ship's mess hall. Our visitor badges gave us a free meal,
a main item, side item, drink. I had a turkey & cheese sandwich, fruit
juice, and a pastry dessert.
There was a closing keynote speaker from Honeybee company that I
passed up for fatigue. I went home after the lunch and a quick walk
around in the Space Fest on the pier.
Since the audience was already on the Intrepid premises it could
stay after the workshop for the Space Fest until closing. It could
also knock off for supper and return in the evening for the Astronomy
Night with NYSkies.
Juice box on Jupiter
------------------
Altho most home astronomers and educators know something about
gravity, it is hard to show how gravity differs on other planets. We
are immersed in a one gravity, that of Earth near sea level, with no
feasible way to modify it.
Tom Barry, Intrepid Museum, developed an entertaining way to make
believe we have different gravity. His props were several common
household objects filled with plaster to give them different weights.
For each item he prepared eight, one for each planet, leaving out
Pluto for now.
Each item had a proper amount of plaster to make the weights among
them were proportional to the gravity of each planet. By hefting the
set of eight the audience feels how heavy an item is one a planet
compared with Earth. The set of eight is tagged with numbers in random
order. A tip sheet links the number to planets.
The items were, as I can remember, pencil case, glue bottle, juice
box, textbook.
Order of planets
--------------
Barry first asked a volunteer to line up pictures of the planets
'in order' on a display stand. The pictures were to size scale from
giant Jupiter to tiny Mercury. The first volunteer lined the pictures
up in distance order from the Sun, Mercury thru Neptune.
Tom then added that he did not stipulate WHICH order to set up the
pictures! Were there other sequences for the pictures? Two more
volunteers tried. One put the pictures in alpha order, Earth thru
Venus. An other did size from Jupiter thru Mercury.
The lesson so far is that there can be many ways to organize
things, not just in a one correct or proper way. Hw left the pictures
in size order for the rest of the session.
Size and mass
-----------
He gave the audience sets of the objects and asked it to line them
in order of weight, either way from heaviest or lightest. This was
actually a bit tricky because certain planets have about the same
gravity and just by hefting some objects were close in weight. My
group, at one table, got the glue bottles. Jupiter was easy to pick
up, so was Mercury. The others took a more careful touch. After a few
minutes we had our bottles lined up. The other tables had their
objects lined up by that group's agreement.
Tom Barry then discussed what causes the gravity of a planet, the
combination of planet mass and size. The pictures on display were
ordered by size but there is no mass information in them. He changed
them around to a mass order, following a tip sheet. Now the sizes were
all mixed up.
He tried to distinguish mass and weight but his use of oldstyle,
which he apologized for, got in the way. There is no common unit of
mass in oldstyle, there being several ad-hoc ones. None is generally
accepted. In fact, since we went metric there are no longer any formal
definitions for oldstyle unit, except as based on the metric ones.
It is really, like really, tough for a person living only under a
uniform gravity, like on Earth, to imagine that the same mass, amount
of material, can have different weights else where. At best Barry did
get thru that a person as he travels from planet to planet maintains
the same (except for effects of space travel) amount of material in
him. His weight varies as he is on a this or that other world.
He weighed the textbooks on a package scale dimensioned in
oldstyle pound and ounce. 16 ounce make one pound. He wrote down the
weights for each and compared them with the line-up of the textbook
group. It had the books in about the correct order.
Practical issues
--------------
This exercise assumes props already prepared. There was no scheme
to build them as a classroom activity. The teacher or other adult
would build the sets and they are then safekeeped for use.
The object has to be one that can be filled with a dense viscous
material, then sealed shut against tampering. The glue bottles, pencil
case, juice box were good choices. The textbooks had to be cored out,
filled, and glued shut.
Loose material, shot, sand, water, slushes inside the container
and spoils the notion of a solid object. Plaster is good because it is
a liquid for measuring and pouring, then it solidifies.
Each item in a set must be identical, except perhaps for the
flavor of juice and color of pencil case. But identical appearance
does remove a potential distraction from the exercise.
The absolute weight is not important. The objects to hand could
weigh a few grams to many kilograms. The best items are those that can
be handled on a table and are familiar in a school setting.
I do mean grams and kilograms equivalent under Earth gravity. When
we say that one kilo 'equals' 2.2 pound we mean that a one kilo mass
on Earth will tip an oldstyle scale at 2.2 pound. On an other planet
that kilo mass registers something else..
Barry didn't handle 'weightless' effects in orbit. The 'Living in
space' talk did. In essence, both the vessel and its occupants and
contents are falling under gravity at the same rate. Relative to each
other they have no motion except local drifting and floating.
Proportion
--------
It may seem easy to make a set of objects proportional to their
weight on other planets. Just start with the 'surface gravity' figures
from any astronomy textbook and measure out the fill proportional to
them for each container.
Not so simple. The container has some tare and the fill adds to it
to make the total weight. Here's one way to get things right way
round. Take the smallest gravity planet (which may be a satellite or
asteroid, not only a main planet) and call it unity. Leave that item
empty but do seal it. Its empty weight represents its weight on the
planet of lowest gravity.
For each other planet, take the ratio of the gravity, from the
textbook, and subtract one. That's the amount of fill in that planet's
container. If a planet's gravity is 7 times that of Mercury, the
least gravity in this exercise, the fill has to be six units, not
seven, for that item. The remaining unit, to make seven, is the very
empty weight of that item.
Measuring the fill can be by spoonfuls, area of spatula blade, cc
reading on a beaker. You may want to use discardable tools and vessels
if the fill is not easily washed out.
Textbooks
-------
Mr Barry assumed that most potential containers can be found in
the home or purchased. In the latter case any original filling, like
glue or juice, can be washed out. Textbooks may be hard to come by. He
suggested a couple sources, like a school's warehouse having books to
be discarded and commercial firms that sell prior editions of books.
After the session I explained that in New York City many, if not
most, schools are converting from printed textbooks to digital media.
There could be a flood of discarded books in a year or so. An other
source could be the school library, most of which are tossing 'old'
books. If there be a set of eight, for a popular title, they could be
had for the effort of dumpster diving.
Bagging it
--------
Tom then with his tip sheet let each table set its set of objects
against the planets by weight. The numbers on the items were random so
those of a one table's set did not match an other's.
With all the items set against their planets, Barry put each
planet's items into a small Intrepid tote bag. These he passed around
to the audience. The bag for Jupiter was quite the heaviest of all,
again illustrating the gravity there compared to Earth's or Mercury's.
The session closed with brief maths. He wrote on a white
blackboard the Newton equation for gravity, explaining how both the
planet's mass and radius yield the surface gravity.
Extra topic
---------
The gravity of a planet is expressed in several ways. One is just a
multiple of Earth's. Another is by the escape velocity from the
surface. And an other is by acceleration under freefall. One other
rarely cited is force per unit mass, which is the basic meaning of
gravity field strength. It says directly how strong is the gravity
force on a unit of mass placed in it.
The acceleration of gravity on Earth at sea level is 9.81
meter/(second)^2). This is also the force, acting on each kilogram of
mass, 9.81 newton/kilogram. As a maths trick, when ever in calculation
you have m/s2, you may find it convenient to replace it with N/kg or
vice versa. The two are dimensionally equivalent.
Escape velocity comes from the kinetic energy needed to overcome
gravity and reach free space. This is stricta mente at infinity
distance away but in astronautics it's 1-1/2 million kilometers, as
far as the Earth-Sun L1 Lagrange point. It's equal to about 62.7
million joule/kilogram.
If we deliver this energy to a unit mass as movement in the upward
direction we can remove it from Earth gravity. One way is to walk it
up an indefinitely long stairs. An other is to give all the energy in
one impulse like a cannonball. This was a serious, if impractical, way
to plan space travel in the 19th century!
Today we use cannonballs without the barrel or muzzle. The gases
pushing the 'ball' the rocket and payload, that would be created by
the explosion of gunpowder, is created by rapid combustion of fuel
carried on the rocket. While it looks like the rocket powers itself
all the way to its target planet, it burns for only a few minutes,
maybe a half hour at the most. After then it coasts in freefal like
the cannonball all the way to the target. The energy of escape is
given to the rocket in an impulse that shows up as the immense speed
of 11.2 km/s or 40,300 km/h.
In today's astronautics getting this much energy into a n object
to send it into space is insanely expensive. No matter what method is
eventually used for future space travel we must in the end deliver
that 62.7megajoule for each kilogram of mass.
A common mistake is to count for the uplifted mass just the
payload, the capsule or satellite. It must include EVERYTHING that
lifts off of Earth, the payload, the rocket hull, fuel and oxidant,
machinery, avionics, flight support, the whole shebang.
One of the prime reasons for using sections or stages in rocketry
is to discard the used up parts of the rocket. This lessens the mass
remaining to push into space. It is under toady's regime of space
travel utterly impossible to carry an entire rocket from liftoff to
the target. SO much of it would be dead mass, no longer needed for
further use in the flight, but it must be pushed along with that same
energy per unit mass.
Living in Space
-------------
The other workshop I took was 'Living in space' chaired by Michael
Sassi from Cradle of Aviation. He discussed in freeflow dialog the
methods of dealing with conditions and hazards of human spaceflight.
Here i elaborate on his explanation of mass, weight, and escape
velocity, as supplement for 'Juice box in Jupiter'.
Gravity in space
--------------
Sassi emphasized that there is gravity in outer space, else how
would the Earth and planets stay in orbit around the Sun. In fact, in
low Earth orbit the gravity field is still about 90% that at sea
level. What looks like zero-G in orbit is really simultaneous
freefall of the spacecraft, occupants, and contents. All are falling
at the local acceleration of gravity, around 9 m/s2. Since everything
is falling at the same rate, there is no gross motion of any part
relative to an other. There is local drifting and floating.
The freefall is just like a cannonball, only the elevation and
speed are so great that the arc of fall is concentric with the arc of
the ground. More accurately the spacecraft arc of fall never
intersects the ground. The craft circles around the world.
More mass and weight
------------------
Sassi, like Barry, used oldstyle units. He cleverly explained mass
and weight by using orbit and Moon as locations for an astronaut. On
Earth the astronaut feels normal gravity, which when he returns from a
zero-G duty on ISS takes several weeks to acclimate to.
In orbit he is in freefall with ISS. There is no gravity
resistance for his muscles to work against and gain natural exercise.
SAme for circulation of body fluids and organ that rely on gravity to
function. Among the crucial tasks on ISS is constant exercise on gum-
like machines, to lessen the loss of muscle and bone strength and to
stimulate body fluid circulation.
On the Moon the surface gravity is 1/6 Earth's. The astronaut can
take long hops and carry loads too heavy on Earth. His spacesuit on
Earth weighs about 300 pound (about 135kg) and would crash him to the
floor like a Mediaeval iron knight's suit. On the Moon he feels it
like an arctic coat of only 22kg.
Mike reminded that the spacesuits at public appearances, like
Space Fest, are only shells. They are not at all space-worthy
garments.
Escape velocity
-------------
Mr Sassi cited the escape velocity but missed its meaning as an
impulse of cannon shot for the spacecraft. He probably allowed that
for the time within horizon there will be no other method for lifting
mass off of Earth but combustion chemical rockets.
He demonstrated the Apollo trips with a model of the Saturn-V
rocket. It was like the kits in the 1960s-1970s, but seemingly more
robust. As each segment was snapped apart, Mike detailed its function.
He finished with the splashdown of the command module with its three
astronauts.
Most in the audience was awed that so humongous a rocket, taller
than the Statue of Liberty, was needed to carry three people and a
capsule to the Moon! The grossest bulk of that rocket was the kerosene
and oxygen to push, like a cannon, the space capsule up to 62.7
megajoule for each of its millions of kilogram mass.
From the Moon with ts far lesser gravity, a tiny module blasted
off and joined the orbiting service module. Back at Earth the commend
module separated from the service module and splashed down for
recovery. Isn't there a more effective way to furnish that energy to
such a small vessel, the size of a mini sedan? So far there isn't.
Some maths
--------
When Newton worked out his theory of gravity he applied it to
individual 'particles' that attract every other 'particle'. His law of
gravity, he believed, worked on such particles. The usual statement is
force = -gamma * mass1 * mass2 / (separation ^ 2)
Mass1 is the first body like a planet. Mass2 is the other object like
a moon or spacecraft. Separation is the distance between the two. If
the bodies were 'particles' the distance is that between their point
locations.
Gamma, also G, is the proportion constant that jimmies the units
on both sides of the equation. It's value is about 6.67e-11 N-m2/Kg2.
By this Newton formula there is for the fist time the clear
distinction between mass and force, concepts only loosely bantered
about previous to his time.
The minus signum is a convention from the way we measure
separation and force. The separation is positive outward from mass1 to
mass2 but the force is toward mass1. Oppositely for the force of mass2
on mass1.
Newton knew that his 'particle' model can't work for bulk masses
like planets. A handful of dirt has far too many particles to sum up
for the mass of the Earth. And he had no idea what the Moon was made
of. He set out to prove, omitted here, that a sphericly symmetric and
radially layered body behaves as if it was a point at its center that
contained the entire mass. He replaced planets with point masses, as
even today most solar system astrodynamics is handled.
By dividing thru by mass2 we get the force per unit mass under the
gravity of mass1. This is the glatt meaning of gravity field strength.
Galileo first showed this in a less rigorous way by observing that all
bodies fall at the same acceleration. 'Heavy' objects do not fall
faster than 'light' ones.
force / mass2 = -gamma * mass1 / (separation ^ 2)
The false understanding came from the usual case that a heavy body
is also dense and presents less resistance in air. Galileo removed the
density factor by using globes filled with different materials and
dropping them from a high balcony. It is not certain if he really did
this at the Leaning Tower of Pisa, but he could have.
This gravity field strength is what we mean for 'surface gravity'.
Its units are newton/kilogram. Separation for surface gravity is the
radius of the planet from its center to the surface.
Many planets have no solid surface. 'Surface' in astronomy means
the visible outer envelope of the planet's globe, the top of opaque
clouds, and not only a rocky or liquid terrain.
Newton also worked out general laws of motion for all kinds of
force, not just gravity. He found that
force/mass2 = acceleration = (change of speed-direction) / time
By matching this with the formula above we have
force/mass2 = acceleration = gravity field strength
This is how we can exchange meter/(second)^2 and newton/kilogram. They
are equivalent quantities.
An other quantity for gravity is the energy in a gravity field. It
takes work to move a particle around in gravity, like the thrust of
rockets. The maximum work is that to move a particle from the planet
surface to infinite distance away. This lets the particle escape from
the planet and not fall back on its own.
The formula for this escape energy is
escape energy / mass2 = -gamma * mass1 / separation
Moving from one place, separation, around mass1 to an other
changes its gravity energy. By setting one separation to infinity, the
energy there is zero. Separation -> infinity; right side -> zero. All
of the difference of energy is that at the other separation. When
numbers for gamma and other parameters are plugged in we get 62.7
MJ/kg for Earth.
The formula does not stipulate HOW this energy is applied to the
body to get it off of Earth. There are many ways in theory, some
talked up in science-fiction. None so far are practical in
astronautics except giving all of the energy at liftoff, as if
shooting the body out of a humongous cannon.
Delivering suddenly, within many minutes, a speed upward of 11.2
km/s is equivalent in kinetic energy to the gravity energy needed for
escape. This is the whole pwah of escape velocity.
It is NOT REQUIRED to attain the escape velocity if we had other
means of supplying the escape energy, like hauling the body into space
with an infinitely tall derrick. It is only because we got no other
means but chemical combustion, the cannon method, that we hype escape
velocity as a necessary fact of astronautics.
Conclusion
--------
Space Fest was a very substantial spacefaring show, one of the
most elaborate in the entire United States. It, if continued in future
years, will be an absolute most-see event for all spacefaring fans.
More than just Space Fest, the Intrepid ship has a, well, boatload
of space-related exhibits and shows. many ran concurrently with Space
Fest, like the educators workshops. Mind well that while Space Fest is
free on the pier, activites in the ship require the regular admission.
If going on the ship, be SURE to ask for the admission AND
Shuttle-Soyuz stepup. The added amount is $7. Unlike the general
ticket, which allows reentry, like to take lunch in the surrounding
streets, the Shuttle-Soyuz coupon is handed in at the pavilion gate.
Once you leave the pavilion you can not reenter.
An addition this year, not elaborated in this piece, was Astronomy
Night. Intrepid holds several per year at irregular intervals. The one
with Space Fest was a bit weak due to haze and humidity in the sky.
Never the less, for the 200ish in the audience, the talks and films on
the pier under the Concorde aircraft were well worth the ride to
Intrepid on that evening.
For what started out in the 1970s as a military relic, Intrepid
moved to the upper ranks of space education, specially since the
entire ship was rebuilt in the late 2-thous. It is expanding its
'space' activities to complement its emphasis on air and sea, the
domain of the original aircraft carrier.
Space Fest and collateral events were successful, attracting major
corporate contributions and NASA funding -- under the thumb of
sequestration! -- and massively well attended by over a quarter
million people. This level of public support and interest speaks
loudly that if you want solid wholesome spacefaring nourishment, with
allied sciences like astronomy, be to New York.