Solar Impulse 2


Solar Impulse is a Swiss long-range, experimental, solar-powered aircraft project which has been running for a number of years and is used to promote the use of alternative renewable energy sources related to new technologies to allow decreased dependence on fossil fuels.

( )

Solar Impulse 2 (SI2) has been built in an attempt to achieve the first round-the-world flight powered solely by energy from the sun.

SI2 is a single seater aircraft made from carbon fibre and has a wingspan of 72m, which is wider than a Boeing 747 jet. It has a compact cockpit space of only 3.8 cubic metres to accommodate a single pilot. The overall weight of the aircraft is 2300kg.

A total of 17,248 solar cells are built into the wings, fuselage and horizontal tailplane covering a total surface area of 269.5 m2. They collect up to 340kWh of solar energy per day to drive 4 electric motors and to charge the lithium polymer batteries. The batteries are used to allow SI2 to fly during the night.

The four engines, each generating a maximum power of 17.5hp, are mounted below the wings and each have a 2 blade propeller with a diameter of 4m. The entire system has an efficiency of 94%.

There are 4 batteries which have an energy density optimized to 260 Wh/kg and are insulated using high density foam. They are mounted in the four engine housings and weigh a total of 633kg which is slightly more than 25% of the overall aircraft weight.

SI2 flies at a speed between 20 and 77 kts. Energy usage is optimised by using a combination of solar energy with the potential energy created from the aircraft height.

During the day the pilot slowly ascends to a high altitude using solar energy to drive the aircraft and charge the batteries. As the sun sets, the pilot reduces the power to the engines and begins a gentle descent of around 0.4m/s to an altitude of between 1000-1500m where level flight is maintained at around 25kts. This cycle is repeated for each day and night of flight.

The driving force behind the project are also the 2 pilots.

Bertrand Piccard, a doctor, psychiatrist, explorer and aeronaut, who made the first non-stop round-the-world balloon flight, is the initiator and chairman.

André Borschberg, an engineer and graduate in management science, a fighter pilot and a professional airplane and helicopter pilot, is the co-founder and CEO.

SI2 set off from Abu Dhabi in March 2015 in a multi-leg attempt to fly around the world powered by the sun’s energy.

The flight started from Abu Dhabi, on March 9 2015. The route includes stop-overs in Oman, India, Myanmar and China. Crossing the Pacific Ocean with a stopover in Hawaii then flying across the U.S.A. and over the Atlantic Ocean, before heading back to Abu Dhabi.

Andre has just completed one of the most challenging legs of the round-the-world flight consisting of a journey which was to last 5 days and nights

SI2 left Nagoya (Japan) on June 28 2015 at 18:03 (UTC) and arrived in Hawaii on July 3 2015 at 15:55 (UTC). The total flight time was 4 days 21 hours and 53 minutes travelling 7212km at a maximum altitude of just over 23000ft and an average ground speed of 38 mph.

Full details about this leg of the journey can be found at

During maintenance and checks after landing in Hawaii it was discovered that the batteries had suffered irreversible damage caused by overheating. Repairs will take several months and the round-the-world trip has been postponed until spring 2016.

Latest news and updates can be found at


Rosetta – A Milestone in Space Travel

Image: ESA/NASA – SOHO/LASCO Acknowledgment: The image of the comet was taken with the navigation camera on Rosetta (ESA/Rosetta/NavCam).

Rosetta is the first space mission in history to rendezvous with a comet, escort it as it orbits the Sun, and deploy a lander to its surface.

It is an ESA (European Space Agency) mission with contributions from its member states and NASA. The Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI.

Complete details of the project can be found at

Rosetta was launched on board an Ariane-5 rocket on 2 March 2004 and arrived at Comet 67P/Churyumov-Gerasimenko, around 675 million km from the Sun, on 6 August 2014. It actually travelled for a total of 6.4 billion km on a journey which included circling the Sun 4 times on wide loops in the inner Solar System and passing through the asteroid belt twice.

The spacecraft dimensions are 2.8 x 2.1 x 2.0 metres and there are two 14-metre-long solar panels with a total area of 64 square metres. From tip to tip, the spacecraft spans 32 metres. Rosetta’s total launch mass was 3,000 kilograms, the orbiter being 2,900 kg of which 1,670 kilograms was propellant. The lander weighs 100 kilograms.

Commands are sent periodically from Earth to readjust the spacecraft’s trajectory. At its furthest point from Earth, these take 50 minutes to reach the spacecraft. On reaching the comet, messages from Earth take about 28 minutes.

The comet is about 4km across and its shape has been likened to a “rubber duck”.

This image shows the comet from about 102km away on 11 Aug 2014.


This image shows the comet from about 83km away on 20 Aug 2014.


The 7 hour descent began on 12 Nov 2014. Touchdown takes place at walking speed which is less than one metre per second.

This image was taken by Philae’s down-looking descent ROLIS imager when it was about 40 m above the surface of Comet 67P/Churyumov-Gerasimenko. It shows that the surface of the comet is covered by dust and debris ranging from mm to metre sizes.


The large block in the top right corner is 5 m in size. In the same corner the structure of the Philae landing gear is visible.

The aim of the ROLIS experiment is to study the texture and microstructure of the comet’s surface. ROLIS (ROsetta Lander Imaging System) has been developed by the DLR Institute of Planetary Research, Berlin.

Philae completed a successful landing on the surface of the comet confirmed at 16:03 GMT on the 12th November 2014. Later analysis of data returned from the lander showed that it touched down 3 times having initially bounced off the surface a couple f times, the first time travelling for about 1km at a speed of 38 cm/s for about 1 hour 50 minutes and the second time travelling at about 3cm/s landing 7 minutes later.

Although the initial touch down appears to have been inside the predicted landing area, the final resting place of the lander is reported to be close to a rocky wall with one of its 3 feet in open space. Due to the location of the lander, it is also reported that the solar panels are only receiving 1.5 hours of sunlight per 12.4 hour comet day.

The battery lifetime of the lander is about 64 hours and with limited re-charging available it may not be possible to achieve results from all of the planned experiments.

On the 14th November 2014 Philae has managed to return all of its housekeeping data, as well as science data from the targeted instruments, including ROLIS, COSAC, Ptolemy, SD2 and CONSERT. This completed the measurements planned for the final block of experiments on the surface.

In an attempt to receive more solar energy, the lander’s body was lifted by about 4 cm and rotated about 35° but as the last science data fed back to Earth, Philae’s power rapidly depleted. Scientists hope that at a later stage of the mission, as the comet gets nearer to the Sun, there may be enough solar illumination to wake up the lander and re-establish communication.

The Rosetta orbiter will continue to orbit the comet and continue to capture data for further analysis.

Experiments on the mission consist of the following packages:

Orbiter science instrument packages:

  • ALICE Ultraviolet Imaging Spectrometer
  • CONSERT Comet Nucleus Sounding Experiment by Radio wave Transmission
  • COSIMA Cometary Secondary Ion Mass Analyser
  • GIADA Grain Impact Analyser and Dust Accumulator
  • MIDAS Micro-Imaging Dust Analysis System
  • MIRO Microwave Instrument for the Rosetta Orbiter
  • OSIRIS Optical, Spectroscopic, and Infrared Remote Imaging System
  • ROSINA Rosetta Orbiter Spectrometer for Ion and Neutral Analysis
  • RPC Rosetta Plasma Consortium
  • RSI Radio Science Investigation
  • VIRTIS Visible and Infrared Mapping Spectrometer

Philae lander science instrument packages:

  • APXS Alpha Proton X-ray Spectrometer
  • ÇIVA / ROLIS Panoramic and Microscopic Imaging System
  • CONSERT Comet Nucleus Sounding Experiment by Radio wave Transmission
  • COSAC Cometary Sampling and Composition experiment
  • PTOLEMY Evolved Gas Analyser
  • MUPUS Multi-Purpose Sensor for Surface and Subsurface Science
  • ROMAP Rosetta Lander Magnetometer and Plasma Monitor
  • SD2 Sample and Distribution Device
  • SESAME Surface Electrical Sounding and Acoustic Monitoring Experiment

Philae is the island in the river Nile on which an obelisk was found that had a bilingual inscription including the names of Cleopatra and Ptolemy in Egyptian hieroglyphs. This provided the French historian Jean-Francois Champollion with the final clues that enabled him to decipher the hieroglyphs of the Rosetta Stone and unlock the secrets of the civilisation of ancient Egypt.