GCAT: General Catalog of Artificial Space Objects

Jonathan C. McDowell


Launch Profile Codes

The launch profile codes are provided in the Category field of the launch lists, for orbital launches only.

This field encodes the target orbit type (LEO, GEO etc.), the upper stage(s) disposal mode, and the number of launch vehicle related debris objects generated during the launch phase (later stage breakups are not included). Note that the data in this field represent the intended result of the launch, not the actual result. It can be used to track the evolution of space debris mitigation practices used by launch agencies.

The format of the launch profile code is:


where XXX is the orbit code for the target orbit, CC encodes the planned upper stage(s) disposal mode, and N is the number of other debris objects planned to be left in orbit from the launch vehicle (not counting objects released by the payload, although there is some ambiguity in that).

The target orbit codes are:

Orbit codeMeaning
DSODeep space orbit (Earth orbit with apogee beyond 150,000 km)
EEOEarth escape orbit
GEODirect geosync insertion
GTOGeosync transfer orbit
HEOHighly elliptical orbit (except MTO, MOL, DSO)
ISSInternational Space Station
LEOLow Earth Orbit (other than SSO, LSS, ISS)
LSSLEO space station other than ISS
MEOMedium Earth Orbit
MOLMolniya orbit
MTOMEO transfer orbit (with payload performing MEO circularization)
SSOSun-sync orbit
STOSupersync transfer orbit (apogee more than 45000 km)
XOExtraterrestrial launch (e.g. launch from lunar surface)

The next part of the launch profile code indicates what measures are taken to dispose of each upper stage which reaches orbit, or is close to reaching orbit. This section has one,two or three letters, depending on the number of upper stages reaching orbit.

Disposal codes are not included for extraterrestrial launches.

For example, OL means that one upper stage was left in orbit with no orbit change, and a second one was left in orbit with a perigee lowering burn carried out after payload deployment.

Disposal codeMeaning
AStage left in Earth orbit, but remains attached to payload by design.
BStage made depletion burn which boosted it to higher Earth orbit.
DActively deorbited to destructive reentry
EStage placed in Earth escape orbit
LSmall perigee lowering burn to reduce orbit lifetime (but not meeting criterion for P)
OLeft in Earth orbit for later uncontrolled reentry
PPerigee lowered to 180 km or less for rapid decay, or stage left in orbit with that low a perigee to start with.
RRecovered intact for possible reuse (so far, space shuttles only, considered as upper stages).
SStage left in marginally suborbital trajectory for targeted reentry on first orbit. Stages with perigees above -1000 km are included.

The S cases are typically ones involving disposing of a large core stage by leaving it slightly suborbital and making the payload or a small insertion stage complete the orbit insertion (for this purpose, the Shuttle External Tank is counted as a stage). This is a standard way of avoiding leaving a big stage with a non-restartable engine in low orbit, and is included to highlight this responsible strategy (and as a contrast to cases such as the CZ-5B).

Finally the number of other launch vehicle-related intentional debris objects is listed. Accidental debris, such as from upper stage breakups, is not included here. Typically the objects noted are tumble weights, multi-payload adapters such as Ariane Sylda5, or payload release hardware such as Starlink tension rods.

For example, 'Sat GTO SO 1' indicates that the launch was targeted for geotransfer orbit, that one stage was marginally suborbital and another was left in orbit for uncontrolled decay, and one additional debris object was left in orbit.