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StarTravelTM
Features
Circular, Elliptical and Parabolic/Hyperbolic Orbital Analysis
1) Plot Sub-orbital, orbital and escape trajectories around planets in the solar
system knowing Burnout velocity (Vbo) and Flight-path angle at burnout (f).
2) Determine distance traveled from liftoff to impact (X) along planet curvature
and sub-orbital flight path knowing Maximum altitude at burnout (Hb) and Down
range distance at burnout (Xb).
3) Free flight angle
from liftoff to impact (y), Sub-orbital flight time or orbital period (T),
Planetary orbital velocity (Vcs), Planetary escape velocity (Ve) and Solar
system escape velocity (Vsun) are all displayed in
red
for easy
review.
4) Zoom-in to see near-planet trajectories for parabolic (e=1) and
hyperbolic (e>1) flights when burnout velocity (Vbo) and flight path angle (f)
are specified.
5) Determine velocity at origin planet sphere of influence (V00)
and Flight time from burnout to destination orbit (T) for parabolic and
hyperbolic trajectories (e>1).
6) View detailed instructions, StarTravelManual.pdf,
by clicking D’Click for Instructions on
the main screen.
Heliocentric and Hohmann Orbital Transfer Analysis
7) Determine minimum energy (i.e. velocity) required for heliocentric and
Hohmann transfer orbits from Earth to other planets in the solar system and
the Moon.
8) Determine velocity change from liftoff to burnout (dV) required for orbital insertion into heliocentric orbits
and Hohmann Transfers to the planets and the Moon.
9) Predict spacecraft velocity of approach with destination planet while on
the transfer ellipse.
10) Predict time of flight from burnout in Earth orbit to interception of
destination planet.
11) Specify miss distance for the computation of heliocentric dV and time of
flight.
12) Solar System Calculator displays current position of the planets, distance
from Earth to the planets and orbital periods of the planets in the solar
system.
Relativistic Star Travel Analysis
13) Determine Earth elapsed time and star ship elapsed time (proper time) for relativistic star travel (0.3c
< V < 1.0c).
14) Determine starship Mass Ratio requirements as a function of relativistic speed and
exhaust velocity.
15) Display Doppler color shift on forward and aft star light as viewed from the
starship.
16) Use one of three acceleration-velocity profile options for travel to the
stars:
a) Constant
velocity (G = 0, V = constant).
b) Constant acceleration (G = constant, Vmax = speed of light (c)
if distance is great enough). See note below.
c) Constant acceleration then constant velocity
coast (G = constant, Vmax = constant).
Note:
Constant velocity and constant acceleration, Options (a) and (b) are not
practical for realistic star travel. For example, unbounded acceleration at
modest G-loading will rapidly allow a starship to approach the speed of light
(at 1G acceleration a starship will attain the speed of light within 1 year
proper time). As a starship approaches the speed of light infinite energy and
therefore infinite Mass Ratio (MR) is required. Instead, the method of
accelerating to a modest coast velocity, Option (c) is the preferred method, making star
travel feasible within the lifetime of a human being at moderate acceleration
(0.1G’s to 1.0G’s) and modest maximum velocity (0.1c to 0.5c).
Summary of Basic StarTravelTM
Features

Sub-orbital,
Orbital and Escape Trajectory Analyses
Back
As illustrated
in Figure-1 trajectories around a massive object like the Earth, Mars and the
Moon follow one of a family of curves called conic sections. Depending on the
specific energy (E), angular momentum (h) and mass (G*M) of a body the
eccentricity (e) of an orbit will determine if the transfer orbit is a circle
(e=0), ellipse (e<1), parabola (e=1) or hyperbola (e>1). The orbital elements of
a body including the eccentricity (e) of an orbit are determined by burnout
velocity (Vbo), flight path angle at burnout (f),
burnout altitude (Hb) and down range distance (Xb) of an object for a two-body
astrodynamic analysis. Because there is not enough space here to fully detail the orbital
mechanics used in StarTravel please refer to the reference list in the
included instructions (StarTravelManual.pdf).


Figure-1, Conic sections defined
by eccentricity (e) and the other orbital elements.
To perform
sub-orbital, orbital and escape trajectory analyses click Suborbital, orbital
and escape trajectory under Trajectory Selections in the top toolbar.
The input data for a sub-orbital trajectory and the resulting plot of the
trajectory are illustrated below. This analysis includes the
ability to determine time of flight (T) for sub-orbital and orbital flights
(e<1). For hyperbolic and parabolic interplanetary flights (e=1 or e >1) the
Flight time from burnout to destination orbit (T) represents the flight time in
days or years to intersect the orbit of the planet selected using the
Destination Planet orbit pull-down menu.

Figure-2, Example of sub-orbital
flight.
Heliocentric and
Hohmann Transfer Analyses
Back
Transfer
orbits from Earth to most of the planets in the solar system may be considered
to be elliptical and co-planar. For example, a Hohmann Transfer between Earth and
Mars may be achieved when the elliptical transfer orbit is tangent to Earth’s
orbit at departure (v1=0 deg) and tangent to Mars orbit at arrival (v2=180 deg).
This kind of interplanetary transfer orbit is called a Hohmann Transfer and
represents the minimum delta-velocity (dV) required for Mars orbital insertion
from Earth orbit. Other heliocentric (around the Sun) orbits to Mars and the
other planets are possible if the transfer orbit intersects both the origin
planet orbit and the destination planet orbit.
For example, when traveling from Earth to Mars the following Hohmann Transfer is possible. SpaceTravel
results for Time of flight from burnout to intercept to Mars from Earth
is 258.93 days with an Orbital Velocity around the Sun at burnout of 32.729 km/sec
and dV for transfer orbit insertion is 2.945 km/sec for orbital
insertion. Please see page 365 of Fundamentals of Astrodynamics or
Table-1 for similar results from that reference.

Figure-3,
Example of Hohmann transfer from Earth to Mars.
Solar System
Calculator
Back
The Solar
System Calculator animates the orbital motion of the planets around the Sun. By
checking the Solar System check box a present-day display of the solar
system appears in the plot area to the right. Positions of the planets in the
solar system as of the date and time displayed in
green
appears in
the orbital plot. By specifying the desired time in the Maximum time from
present input box the user can animate motion of the planets around the Sun.
Also, by clicking the STOP command button the user can “freeze” the
planet positions prior to reaching the maximum time specified. Finally, the
ZOOM slider bar is used to zoom-in and zoom-out of the solar system plot.

Figure-4, Solar System
calculations.
Relativistic
Interstellar Travel Analysis-
Star Travel near the speed of
light (C)
Back
It is
impossible to exceed the speed of light because as an object approaches the
speed of light the inertial mass of an object and therefore its mass approach
infinity. It would take infinite power to accelerate an object beyond
the Einstein limit (C) or “light barrier”. However, because of time dilation as
predicted by Einstein's theory of Relativity, an
astronaut can travel stellar distances, that is many light years (ly) within
his/her own life time while many thousands of years will have elapsed on the
planet of departure or Earth in our case.
For example, if a starship
leaves the vicinity of Earth with a constant acceleration of 0.999998G’s
toward a star located 1000 ly (light-years) from Earth. Determine (a) the elapsed time
on Earth when the starship reaches the star and (b) the proper time on the
ship, relative to Earth clocks. From the Relativistic Interstellar
Travel screen the results are:
a) Elapsed
time on Earth during the flight is 1002.65 years.
b) Elapsed
time on the starship (proper time) during the flight is 13.46 years.

Figure-5
Relativistic Time Dilation and Doppler light shift analysis showing FWD
(forward) star colors.
MODIFICATIONS AND REVISIONS
StarTravel 3.0.0.6 Modifications
1) For the
Heliocentric and
Hohmann Transfer Analyses and the Solar System Calculator the
central Sun image has been replaced by a realistic image of the Sun.
StarTravel 3.0.0.5 Modifications
1) During a Solar System animation each planet's
starting point location in orbit is marked by a hollow white circle.
2) After each Solar System animation the option, Planetary-plots appears.
This option allows the X-Y plot of Planet velocity vs. true anomaly, Planet
velocity vs. elapsed time, Angular momentum (h) vs. true anomaly and Angular
momentum (h) vs. elapsed time. Where, angular momentum, h = 2 dA/dT is
constant for each planet's orbit in agreement with Kepler's second law of
planetary motion. Kepler's second
law states "The line joining the planet to the sun sweeps out equal areas in
equal times" or another words, dA/dT = constant.
3) Fixed the plot position error for the dwarf planet Pluto which becomes
appreciable for elapsed time approaching 100 years. For purchasers of
StarTravel 3.0 please contact AeroRocket to receive your FREE upgrade
to the new version which fixes this error.
StarTravel 3.0.0.1 Modifications
1) The
Solar System Calculator now
uses an iterative solution based on Kepler's second law that states "The
line joining the planet to the sun sweeps out equal areas in equal times"
to compute planetary positions verses time.
2) Easily reset the Solar System
Calculator to its initial starting screen by clicking the T=0 command
button.
3) New version 3 screen images included in the detailed
instructions, StarTravelManual.pdf.
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StarTravel
Minimum System Requirements
(1) Screen resolution: 800 X 600 (2) System: Windows 98, 2000, XP, Vista, NT or Mac with emulation (3) Processor Speed: Pentium 3 or 4 (4) Memory: 64 MB RAM (5) English (United States) Language |
Note: This web page is intended to describe the astrodynamics program, StarTravel and is NOT an instruction manual. The complete 20 page instruction manual is included in the program installation and is called StarTravelManual.pdf. Upon installation, StarTravelManual.pdf may be accessed from the main screen and is located in the StarTravel folder. For more information about StarTravel please contact AeroRocket at john@AeroRocket.com
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