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Rosetta - Powered by Terma

Terma has delivered the power supply unit for the spectacular ESA comet chaser.

Powered by Terma

On 20 January 2014, the Rosetta spacecraft came to life after 2½ years in hibernation. Terma has delivered the power supply for the spectacular ESA comet chaser that was launched in 2004.

Throughout the hibernation, Terma’s power supply, a Power Conditioning Unit (PCU), as the only instrument on board the space craft was active mainly to keep the satellite warm. In August 2014 Rosetta orbited its final destination Comet 67P/Churyumov-Gerasimenko, and on November 12, Philae’s spectacular landing on the comet was conducted. Until present, Rosetta continued to orbit the comet and to carry out numerous scientific experiments and measurements.

Rosetta finale set for 30 September
Rosetta is set to complete its mission in a controlled descent to the surface of its comet on 30 September 2016. The mission is coming to an end as a result of the spacecraft’s ever-increasing distance from the Sun and Earth. It is heading out towards the orbit of Jupiter, resulting in significantly reduced solar power to operate the craft and its instruments, and a reduction in bandwidth available to downlink scientific data.

Combined with an ageing spacecraft and payload that have endured the harsh environment of space for over 12 years – not least two years close to a dusty comet – this means that Rosetta is reaching the end of its natural life.

Throughout the entire mission, Terma’s Power Conditioning Unit has worked continuously to adapt and regulate the power that is extracted from the solar panels to the constant need of the spacecraft’s electrical equipment. Especially during the phases of preparing Philae’s journey and positioning Rosetta correctly for the release of Philae it has been challenging, as Rosetta's solar panels are often not in an optimum position relative to the sun. Everything has been carried out excellently.

The PCU (as seen below) has the size of a shoebox and a mass of 8.3 kg. It is designed so that whatever single failure may occur, it will continue to supply all the power that can be extracted from the solar panels when required.

To extract all solar array power, the PCU is designed with a unique Maximum Power Point Tracking (MPPT) technology, which along with three batteries secures sufficient and constant power for the scientific instruments. The MPPT is an electronic function that constantly regulates the solar array loading to the exact point where the optimum level of electric power is achieved, a loading point that depends on the amount of solar radiation to which the 65 m2 panels are exposed.

Besides the advanced PCU, Terma has also supplied the checkout system which was used for a complete functionality test of the satellite prior to launch. Further, Terma has supplied the so-called software validation facility which was used prior to launch for an independent test of the software in Rosetta’s critical sub-systems.

About the mission

Rosetta's main objective was to rendezvous with, and enter orbit around, comet 67P/Churyumov-Gerasimenko and to perform observations of the comet's nucleus and coma. During the period that Rosetta orbits the comet, 67P/Churyumov-Gerasimenko reached perihelion (the closest point to the Sun in its orbit), allowing for the resulting increase in activity to be measured.

The lander, Philae, was deployed and became the first first probe to perform a controlled landing on a comet. Philae was meant to take samples of the comet’s surface, analyze the material, and send the results of these analyses back to Earth via Rosetta., This could help understand the origin and evolution of the Solar System, in particular investigating the role that comets may have played in seeding Earth with water, and perhaps even life. The lander’s planned mission ended after about 64 hours when its batteries ran out, but not before it delivered a full set of results to be analysed by scientists across Europe.

On 2 March 2004, the Rosetta mission was launched on an Ariane 5 rocket. Rosetta is the first spacecraft ever designed to orbit a comet and release a small lander onto its surface. Since launch in 2004, Rosetta followed a clever route including a number of so-called ”swingbys” around Mars and Earth, where the satellite has used the gravity from the planets to achieve its travelling speed of 60,000 km/h. During the spacecraft’s complicated 7.1-billion kilometer long journey to the merely 3x5 kilometer Comet 67P/Churyumov-Gerasimenko, these swingby maneuvers have been vital for the positioning of Rosetta in the correct orbit during which it gradually sneaks up on the comet, in order to finally release the small lander with its scientific instruments. 

Rosetta calls home after 957 days in hibernation (image courtesy: ESA-C.Carreau)

After 957 days in hibernation and a 10 year journey, the Rosetta satellite started the wake-up procedure on 20 January 2014. At that time, the spacecraft was 825 million kilometers away from Earth and 675 million kilometers away from the Sun.

On 27 March 2014, the Rosetta spacecraft caught a first glimpse of its destination comet since waking up from deep-space hibernation on 20 January.

On 6 August 2014, Rosetta reached its destination, the comet 67P/Churyumov-Gerasimenko, and on 12 November, it dispatched the lander Philae. 


  • The Rosetta stone is discovered in Egypt and provides the key to the modern understanding of Egyptian hieroglyphs
  • The Philae obelisk is discovered in Egypt and becomes an additional key to understanding the hieroglyphs
  • European and American scientists first consider sending a spacecraft to a comet and landing on it
  • ESA initiates the development of the comet chaser mission and names it after the Rosetta stone and the Philae obelisk
Nov. 1993
  • Terma delivers Rosetta Power Conditioning Unit (PCU) proposal to Astrium UK, now Airbus Defence and Space
Feb. 1998
  • Terma wins the contract for development and manufacturing of the Rosetta PCU
May 1998
  • Terma supplies the PCU flight model to Astrium for integration on board the Rosetta spacecraft
Dec. 2001
  • Launch on an Ariane-5 from Europe’s spaceport in Kourou, French Guiana 2
March 2004
  • 1st Earth swing-by (distance from Earth: 1955 km)
4 March 2005
  • Mars swing-by (distance from Mars: 250 km)
25 Feb. 2007
  • 2nd Earth swing-by (distance from Earth: 5301 km) 
13 Nov. 2007
  • Asteroid Steins flyby (distance from Steins: 802.6 km)
5 Sept. 2008
  • 3rd Earth swing-by (distance from Earth: 2480 km)
13 Nov. 2009
  • Asteroid Lutetia flyby (distance from Lutetia: 3162 km)
10 July 2010
  • Enter deep space hibernation
8 June 2011
  • Exit deep space hibernation
20 Jan. 2014
  • Rosetta’s first sighting of its target – 67P/Churyumov-Gerasimenko 
March 2014
  • Comet rendezvous maneuvers (distance from comet: 600,000–100,000km)
May 2014
  • Arrival at P67/Churyumov-Gerasimenko comet
6 Aug. 2014
  • Philae lander delivery
12 Nov. 2014
  • Comet escort phase
From Dec. 2014
  • End of mission
30 Sept. 2016


Rosetta _ESA_ATG-medialab _464

Rosetta in the media

Danish TV 

6 November 2014: TV2 Østjylland: Terms skriver rumhistorie:


6 August 2014: TV2 Østjylland: Terma skriver historie:


1 April 2014: TV2 Østjylland: Et kig ud i rummet:


26 January 2014: TV2 Østjylland: Klar til Mars og Merkur:


20 January 2014: TV2 Østjylland: Rosetta vækkes fra sin dvale:


20 January 2014: TV2 Østjylland: Glæde hos Terma:


18 January 2014: TV2 Østjylland: Hele vores fortid er på spil:



Danish printed media 

9 November 2014: Århus Stiftstidende: Termas kometkarriere når målet:


8 November 2014: dr.dk/Nyheder: Nedtælling til historiens første kometlanding:


8 November 2014: Berlingske Tidende: Nu skal Europa skrive rumfartshistorie:


6 November 2014: TV2 Østjylland: Rosetta ved vejs ende:


12 August 2014: Berlingske Tidende: Meeen... hvor skal Rosetta lande på den forrevne komet?:


6 August 2014: Århus Stiftstidende: Rosetta nærmer sig sit mål:


5 August 2014: Ingeniøren: Efter 10 år og 6,4 mia. km: Nu ankommer Rosetta til komet:


31 March 2014: Jyllands-Posten: Rosetta-rumsonden har taget sine første billeder:


29 January 2014: Århus Stiftstidende: Rosetta har det godt og holder varmen:


21 January 2014: Århus Stiftstidende: Terma går aldrig i dvale:


21 January 2014: Århus Stiftstidende: Se billederne: Terma vækker Rosetta:


21 January 2014: Ingeniøren: Rumsonden Rosetta vågner efter 957 dages dvale:


20 January 2014: Århus Stiftstidende: Hul igennem til Rosetta kl. 19:19:


20 January 2014: Politiken: Rumsonde vågner af sin dvale efter fem ture rundt om solen:


20 January 2014: Politiken: Begejstrede forskere: Nu kan jagten på komet gå i gang:


20 January 2014: Berlingske Tidende: Hul igennem til satellit 825 mio. km væk:


20 January 2014: Jyllands-Posten: rumsonden Rosetta vågnet op fra sin dvale:


20 January 2014: Jyllands-Posten: Kometjæger genoptager historisk mission:


20 January 2014: Berlingske Tidende: I dag skal rumsonden Rosetta vækkes til eventyrlig mission:


20 January 2014: Politiken: I dag ringer vækkeuret 800 millioner km borte:


20 January 2014: Århus Stiftstidende: Lystrup kalder rummet:


19 January 2014: Ingeniøren: Terma-elektronik vækker rumsonde fra årelang dvale:


19 January 2014: Jyllands-Posten: Mandag vækkes en historisk rumsonde:

http://www.jyllands-posten.dk/protected/premium/indblik/ECE6414650/mandag-vaekkes-en-historisk-rumsonde/ (subscription required)

11 January 2014: Berlingske Tidende: Vågn op Rosetta!:



Morten Rahbek - Engineer, Space Electronics - He makes a difference - portrait by the Danish Society of Engineers


Kasper Rasmussen
Director, Communications
T: +45 8743 6091
E: kar@terma.com