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)
Rosetta LAP home page
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
Welcome to Rosetta
Our space weather station to a comet
Rosetta and LAP in a nutshell
Rosetta is an ESA (European Space Agency) mission to a comet, launched
in 2004 and arriving in 2014. We have built a "space weather station",
the Langmuir probe instrument (LAP) to investigate the cometary
environment. En route to the comet, we can do measurements in
interplanetary space and in the environments of Earth and Mars when we
pass by these planets.
The picture below shows Rosetta in space. The large bluish "wings" are
the solar panels which provide electricity for all systems onboard the
spacecraft. The red circles show the locations of the two sensors
of our instrument, LAP.
One of the two sensors is enlarged at the bottom of the picture. The
sensor itself is a titanium sphere 50 mm in diameter, looking goldish
because of its titanium nitride coating.
A Langmuir probe
is a device to measure weak electric currents flowing between the
spacecraft and the surrounding space. "Empty space" is never empty: it
always contains a tenuous gas of electrically charged particles, known
as a plasma. By measuring the current to the Langmuir probe while
varying its potential, we can find out quantities like the density,
temperature and flow speed of the plasma. As pressure is density times
temperature, we measure the three fundamental properties of all weather
stations: temperature, pressure and wind speed: hence we sometimes call
our instrument a "space weather station".
The main target of Rosetta is a comet known as 67
P/Churyomov-Gerasimenko. Comets have always been fascinating to
mankind. Nowadays, we understand that they are not only beautiful, but
that they also may hold important clues to the formation of the solar
system, as they are a sort of uncooked leftovers from the time when the
solar system was baked into its present shape, preserved in a kind of
cosmic freezer for some 4 billion years.
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: