John Pazmino
 NYSkies Astronomy Inc 
 www.nyskies.org 2013 July 17
 2013 August 1
    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. 
    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. 
    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 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 
    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 
    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. 
    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 
    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. 
    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.
    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 
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 
    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 
    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. 
    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.