Speaker
Description
Cubesat missions are often driven by small teams focusing on a
single goal. There is generally only one instrument on-board,
performing one specific measurement, in contrast with large
Earth Observation platforms that hosts half a dozen instruments
provided by several laboratories in an internationally coordinated
project.
The small team main interest is gathering the data. Its members are often
by themselves the end users of their own system, just as in open-source
the developers of a program are users "scratching their own itch", as
the saying goes. Flight dynamics is a necessary chore for the success
of the mission, but not a goal by itself. There are generally no resources
available for this topic, neither in terms of skills nor in terms of
tools. As a result, many cubesat projects end up using the public TLE
provided by SpaceTrack and some on-line path predictors to schedule their
connection to spacecraft for telemetry retrieval. TLE are notoriously low
accuracy (it is a simplified analytical model, and measurements for a given
object are not refreshed as often as the owner would like). This is sufficient
(and widely used) for simple access prediction, but clearly not enough
for more ambitious missions.
As cubesat missions address more and more needs, they reach a state where
spacecraft location should be known with better accurary, for example to
improve the geo-location of the measurements performed by the instrument,
and therefore improving the scientific model resulting from the mission.
Orekit is a free software space flight dynamics library that has been
available under the terms of the Apache License V2 since 10 years. It
is widely used by many major space actors, including agencies, industry,
research and academics. It is used for operational systems, mission analysis,
studies and training. As an open-source library, it can be used to build any
kind of system, from simple ones performing only prediction using TLE to
highly accurate ones managing constellations with station keeping maneuvers
and precise orbit determination. As cubesat now can have on-board GNSS
receivers, it is possible for a cubesat project to perform its own orbit
determination by downloading the data (either high level position-velocity
or low level pseudo-range or carrier-phase) and processing it on ground
with a small Orekit-based program. Orekit as a large community of space flight
dynamics experts that can help smaller teams to set up their own systems.
This talk will present a selection of the features in Orekit that can be
used for cubesat missions with limited resources.
