Space Plasma Physics
Team pages (restricted)
| INSTITUTET FÖR RYMDFYSIK
|| Space Plasma Physics programme, UPPSALA
| Swedish Institute of Space Physics
|| (59o50.272'N, 17o38.786'E)
is an ambitious project catching up with a comet, following it in its
orbit for two years (2014-2016), putting a lander (Nov 2014) and finally
itself onto the surface of the comet nucleus. Our onboard space weather station
LAP was active from start to end!
Back to Rosetta LAP home page
Science with LAP
The basic goal
of Rosetta is to study the origin of comets, the relationship between
interstellar material and its implications with regard to the origin of
the Solar System. The main task of LAP is to investigate, together with
all the other
sensors of the Rosetta
Plasma Consortium (RPC), the
plasma environment of the
comet, to solve riddles related to the comet nucleus itself as well as
to its interaction with the solar wind. The basic parameters measured
by LAP are the density,
of the plasma,
but other parameters can also be estimated (read more on LAP
capabilities below). We fly a similar
instrument, though with one probe only, on the Cassini
spacecraft now orbiting Saturn.
A plasma is a gas of consisting of charged particles. The
basic idea of
a Langmuir probe is to determine the density of a plasma in the
only density can be measured, but
also temperature, drift speed, effective particle mass, electric field,
- Put a conducting probe in
contact with the plasma (we use nitrified titanium spheres).
- Apply a voltage on the probe
(a bias voltage).
- Measure the
current flowing to the probe from the plasma. The denser the plasma,
the higher the current. Voila!
There is still a long way to go to the comet, but we already have some results published:
- When Rosetta flew by Mars in February 2007, we observed the bow shock forming around the planet when the solar wind flows by. The same bow shock was almost simultaneously observed also by Mars Express. The work was published by
Niklas Edberg in Planetary and Space Science (2009).
- We have also published an instrument description in Space Science Reviews (2007).
- Various aspects of comets, Rosetta and LAP have been studied in a series of undergraduate projects: