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RadiusThe average altitude of the orbit. For traditional parking LEO orbits, this ranges from 90km to 250kmEccentricityHow “stretched” an orbit is. Parking orbits almost always aim for an eccentricity as close to zero as possible, that is, a nearly circular orbit.InclinationThe angle between the orbital plane and the equator. This can very greatly depending on mission profile- from polar-orbiting reconnaissance and weather satellites to equatorial communications satellites to satellites with precise inclinations for interplanetary maneuvers and everything in between.
The rocket starts on the launchpad. After the occasional safety test, the engines’ fuzes are ignited, our Ignition Officer runs for cover, and the rocket lifts off the pad with a thunderous roar and the ocassional minor explosion.
At approximately 1km altitude, the rocket begins its "gravity turn"- a fancy term for tilting over just enough to reach orbit while not flipping over and ruining everyone’s day.The new alignment is typically 10-15 degrees east of vertical. This takes advantage of the free velocity boost of Earth’s rotation. Bootstrap Principle #14- always, ALWAYS take anything that’s free.This saves fuel in the long run as it allows for more optimal burns later on.At an altitude of approximately 5km, attitude is switched to prograde- that is, flying directly forward relative to the rocket’s current velocity.After some time has passed, the rocket will now be on a healthy suborbital trajectory. The engines are shut off, or in the case of the BR3.2F Stage 1B burns out.
Following suborbital alignment, the rocket simply coasts along its path until it nears the apoapsis, the highest point in its arch.
Upon nearing apoapsis, the rocket burns prograde until it has entered orbit.This is the largest burn in the entire process, requiring the rocket to gain enough momentum to miss Earth as it freefalls.Once a stable orbit is reached, the burn is stopped.
The rocket now burns normal (perpendicular) to the orbital plane in order to achieve the correct orbital inclination.If the required orbital inclination is small, this step may be omitted. Remember Bootstrap Principle #15- close only counts in horseshoes, hand grenades, and rocket science.
Once inclination is correct, the rocket coasts to apoapsis (highest altitude) or periapsis (lowest altitude), whichever is closer.At this point, the rocket will either burn prograde to increase the altitude at the opposite point, or burn retrograde to decrease the altitude at the opposite point.Once the opposite altitude is correct, the rocket cuts throttle and coasts to that point.Repeat, this time burning at the periapsis if the initial burn was at the apoapsis, or vice versa.Once both burns are completed, the rocket will be in an orbit with all three main parameters within acceptable limits.
Now, the rocket will do any further burns as necessary to go from its current parking orbit to its final orbit. This is the customer’s responsibility- we only get them to orbit. Because remember Bootstrap Principle #4- why go above and beyond when the bare minimum is an option?Some examples of final orbits include:
Getting to Orbit
Getting to orbit is typically the first step for any mission profile offered by Bootstrap Launch Solutions. This page will break down the steps and process for getting to orbit, from launch to a stable parking orbit.
Introduction- the Basics
The majority of space missions at some point have the rocket parked in a stable waiting, or parking, orbit. For some missions this is the final stop. For others, it is merely a stepping-stone for a maneuver to deeper space.
An orbit can be generally described by three parameters:
Image source: Wikipedia
The Process
Step One: Liftoff
Liftoff!
Step 2: Suborbital Alignment
Prograde flight
Step 3: Suborbital Coast
Suborbital path and apoapsis
Step 4: Orbital Insertion
An imperfect but stable orbit. Remember Bootstrap Principle #11- aim for acceptable!
Step 5: Inclination Adjustment
A moderately inclined orbit
Step 6: Altitude Refinements
Burning retrograde at apoapsis to lower periapsis to ~120km
Step 7: To Final Orbit
Common Orbits
Orbit Type
Altitude
Approx. Eccentricity
Approx. Inclination
Geostationary
35,78km
0
0 deg
Low Earth Orbit
120-2,000km
0
0-45 deg
Polar Orbit
120-200km
0
90 deg
Sun-synchronous orbit
600-800km
0
97 deg
There are no rows in this table
Source:
All images Kerbal Space Program 2 screenshots
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