Are there guidelines for orbit design if you're launching a payload for delivery to the ISS? Altitude, maybe phase angle constraints? Orbital approach maneuvers, maybe?

I've figured out how to control a launch for all key orbital parameters at insertion, but while some parameters are well constrained (orbital inclination and longitude of ascending node), others are less so (altitude/velocity/eccentricity).

If the ISS orbits at 400 km, I could plan insertion at 200 km or 300 km, and I could plan the insertion at perigee or apogee or anywhere in between, and I could aim for some phase angle between the ISS and my spacecraft at insertion, but are there any constraints I can use to properly choose the values for these parameters?

Is there a guide book for things of this sort that space launch engineers can refer to when planning their rocket launches/orbital insertions/orbital maneuvers to meet the ISS?

  • $\begingroup$ Not duplicates, but these two answers have some relevant information: space.stackexchange.com/a/44118/6944 space.stackexchange.com/a/44123/6944 Especially see the reference linked in @asdfex 's answer. $\endgroup$ Mar 19, 2021 at 14:09
  • $\begingroup$ There's a ridiculously expensive book (the paperback version is over $100 US), Automated Rendezvous and Docking of Spacecraft. There are many (very many) scientific journal articles about low Earth orbit rendezvous. You are asking us to write a book, and not only that to write a book that is be subject to ITAR restrictions. I don't know why this is ITAR-restricted; multiple foreign governments, some not exactly friendly to the US, have this book. $\endgroup$ Mar 19, 2021 at 16:58
  • $\begingroup$ Some basic guidelines: So long as the cargo on your vehicle doesn't include people (aka astronauts, who are cargo as far as commercial crew providers are concerned), NASA has no guidelines until the vehicle gets close / can get close to the ISS. But once it does get close or can get close, NASA has guidelines galore. Unfortunately, those guidelines are ITAR. Some concepts that aren't ITAR: If a vehicle must leave the approach ellipsoid or keep-out sphere (e.g., rendezvous failure), it must stay out of the approach ellipsoid or keep-out sphere for a specified amount of time. $\endgroup$ Mar 19, 2021 at 17:10
  • $\begingroup$ The vehicle must have waypoints along the approach, places where it keeps relative motion to a minimum. The vehicle must be able to safely abort, even if the vehicle goes dead. The ISS crew must be able to command the vehicle to abort. The vehicle must not plume the ISS, and must not vent liquids, toxic gases, or corrosive particles anywhere close to the ISS. Once docked or berthed with the ISS, the vehicle must not open a channel between the cabin breathing atmosphere and vacuum. Leaks of any kind are highly verboten. There are also requirements about electrical and data connections. $\endgroup$ Mar 19, 2021 at 17:15
  • $\begingroup$ David, I'm not asking anyone to write a book. I'm asking for the name of a book or publication someone has already written. A reference. That is all. I don't want you to write it for me. I just want to know if one already exists. $\endgroup$
    – user39728
    Mar 19, 2021 at 17:20

1 Answer 1


Are there any constraints I can use to properly choose the values for these parameters?

Two key constraints are the approach ellipsoid and the keep-out sphere. Most vehicles have additional constraints the vehicle designers place on the vehicle in the form of hold points.

The approach ellipsoid is an ellipsoid that is centered at the ISS center of mass and is 4 km long along the v-bar, and 2 km wide along the r-bar and h-bar. Most vehicles designed for ISS rendezvous do not plan a maneuver that would enter the approach ellipsoid unless given authority to proceed (ATP). A vehicle that enters the approach ellipsoid without ATP should abort. NASA and Roscosmos will look at the vehicle's flight software to ensure that these constraints are in place.

The keep-out sphere is a sphere centered at the ISS center of mass and has a diameter of 400 meters. A vehicle must not enter the keep-out sphere until give approval (ATP). Most vehicles stop relative motion at a point, (a "hold point") that is a bit outside of the keep-out sphere where they continue to hold relative position (within some deadband) until granted ATP. (They can also be commanded to abort or retreat, or the flight software can decide to abort or retreat at this hold point. Commands to abort or retreat are always in order.)

Most vehicles have an additional hold point well inside the keep-out sphere. From this inner hold point, ATP enables the vehicle to proceed to docking or berthing. A commanded or self-imposed retreat at this inner hold makes the vehicle go back to the hold point outside of the keep-out sphere. Once ATP has been grated at this inner hold point, a commanded or self-imposed retreat makes the vehicle retreat to that inner hold point. A commanded or self-imposed abort makes the vehicle not only exit the keep-out sphere but also exit the approach ellipsoid.

Some vehicles add yet another hold point that is well outside the keep-out sphere but is inside the approach ellipsoid. One key reason for this outer hold is that it enables a retreat from the hold point that is just outside the keep-out sphere to this further out hold point.


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