Solar SailsA team of students working at Delft Technical
University (TU Delft), the Netherlands, are preparing an exciting
experiment to test graphene in space-like microgravity, for potential
future use as a light sail in space-craft propulsion.
The GrapheneX team successfully submitted their experiment proposal to ESA
Education’s Drop Your Thesis! Programme in October 2016. The team
members – Santiago Cartamil-Bueno, Rocco Gaudenzi, Davide Stefani and
Vera Janssen – travelled to Bremen, Germany between 6-17 November 2017
to perform their experiment at the 146 m ZARM Drop Tower.
sails can be used in space as a method of propelling spacecraft using
light from the sun or from Earth-based lasers. When light is reflected
from or absorbed by a surface, it exerts a force that pushes the surface
away from the light source. This radiation pressure can be used to
propel objects into space without using fuel or gases.
thrust generated by radiation pressure is very low. For effective
propulsion, the light sail must have a large surface and be as light as
possible. Graphene is very light and strong, and could be a good
candidate for solar sails. The GrapheneX team plan to investigate how
graphene could work as a light sail in an experiment that simulates the
low-gravity and high-vacuum conditions of space.
The sails to be
tested by the GrapheneX team are graphene membranes, supplied by
Graphene Flagship partner Graphenea. The radiation pressure from shining
high-power laser light onto the graphene membranes should cause the
sails to move approximately 2mm. This displacement will be measured
with a simple microscope to determine the thrust on the graphene sails.
The team plan to use different colours of laser light, to investigate
the exact mechanism of how momentum is transferred to the graphene from
At the ZARM Drop Tower, the experiment – including graphene
sails, lasers and cameras - will be loaded into a capsule and
catapulted the height of the tower. Inside the tower, vacuum conditions
allow the capsule to rise and fall without friction or air resistance,
so that the capsule experiences apparent weightlessness down to
one-millionth of the Earth’s gravitational force. As the capsule
accelerates, the graphene sails will be released into almost
gravity-free free-fall. At this point, the laser will be allowed to
shine onto the graphene chip, and the pressure generated by the laser
falling onto the graphene will be detected. A key challenge of this
experiment is automating the experiment procedures to initiate and
record the results in the 9.3 seconds of free fall.
preparatory work for this experiment is being carried out by the
GrapheneX team at TU Delft, with support from Herre van der Zant (TU
Deflt), Angelo Cervone (TU Delft) and Jian Rong Gao (Delft Space
Institute, the Netherlands). As part of the Drop Your Thesis! programme,
the team are also mentored by Pekka Janhunen (Finnish Meteorological
Institute, Finland). This experiment is supported by ESA Education, the
Graphene Flagship, and the Delft Space Institute.
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