Launch windows
Getting to space is one thing, another thing is arriving where you need to.
Launch windows are what makes this possible. Going to Mars only makes sense if you depart at the right time, otherwise the distance can be significantly longer or you will simply miss.
The same goes for earth orbits. Since earth rotation under the orbital plane, the time angle and direction of launch will determine what orbit you can hit.
Additionally when launching you will always want to head east if your target orbit allows for it - the reason for this is to utilize the earth rotational speed for a free slingshot thus saving dV required.
So when you have got a reputation good enough to start operating commercially, the launch windows are key.
- Missions available when your company reputation and experience is high enough and you have received approval for commercial operations
- Selecting a launch window
In the above example the goal is to get a payload with a mass of 4,000kg into low earth orbit at an altitude of 400km.
But equally important is the orbit. For the payload to do its job, the orbit must be at an inclination of 97.5 degrees, and the RAAN (Right ascension of the ascending node) 45 degrees.
To achieve this, the launch windows have been calculated - picking the best one is up to you. Later launch windows are often better, but debris collision risk poses a major influence. And time, while adjustable, is not free. Neither is dV.
RAAN - Right Ascension of the Ascending Node
Inclination tells you how tilted an orbit is. RAAN tells you where that tilted orbit is placed around Earth.
RAAN is the angle that tells us where the orbit crosses the equator going north, measured around Earth.
Two satellites can have the same altitude and inclination, yet fly over completely different parts of Earth. The difference is RAAN.
RAAN is set mainly by when you launch. As Earth rotates, the launch site passes under different orbital planes. Launching earlier or later rotates the orbit east or west around the planet without changing its tilt.
This is why launch windows matter. Miss the correct RAAN, and you may reach orbit perfectly, just in the wrong place.