Case study

Rosetta

One of the most challenging space missions ever undertaken, this spacecraft studied a comet at close quarters.

Rosetta spacecraft.

Artist's impression of Rosetta. Credit: ESA.

Overview

The European Space Agency (ESA) mission comprised a large orbiter - designed to operate for a decade at large distances from the Sun - and a small lander called ‘Philae’. Each of these carried a comprehensive suite of scientific experiments designed to complete the most detailed study of a comet ever attempted. After releasing its lander, Rosetta spent 22 months orbiting Comet 67P Churyumov-Gerasimenko as the comet orbited the Sun.

The Rosetta spacecraft:

  • launched 2nd March 2004
  • flew by asteroid Steins in September 2008 and asteroid Lutetia in July 2010
  • was put into hibernation as it travelled away from the Sun in June 2011
  • successfully awoke from its 31-month hibernation on 20th January 2014
  • an attempted soft landing of Philae which took place 12th November 2014
  • mission ended on 30th September 2016

Through this challenging mission scientists were able to gather new information and gain further insight on the formation of the Solar System. Comets hold clues to the origins of life on Earth and much of the water on Earth was brought here by comets. The Rosetta mission made unexpected and exciting discoveries, for example, the water detected on the comet was found to be substantially different to the water on Earth and the lander instruments detected the molecules that form the basis for life in the cometary dust.

During the cruise to Comet 67P Churyumov-Gerasimenko, Rosetta helped with research into another comet and studied two asteroids. In July 2005, Rosetta monitored the collision of an ‘impactor’ probe, released from the Deep Impact mission, with the surface of Comet 9p/Tempel 1.

On 5th September 2008 the spacecraft flew past asteroid Steins, collecting a wealth of information about this rare type of Solar System body.

On 10th July 2010 the spacecraft flew close to asteroid, Lutetia. The observations of Lutetia will inform Solar System formation models by determining whether it is an object originating from the outer Solar System and whether it has an exosphere (the outer layer of an atmosphere resulting from a high volatile content).

The Lutetia fly-by was the last opportunity to operate the instruments before the spacecraft entered hibernation for 3 years. The spacecraft’s orbit took it far from the Sun (over 4.6 times the distance of the Earth from the Sun) where power limitations made normal operations impossible.

The spacecraft was successfully awoken from its 31-month hibernation mode in January 2014. On the 6th of August the spacecraft rendezvoused with Comet 67P Churyumov-Gerasimenko and on the 12th of November the mission deployed its Philae probe to the comet; the first time in history that such an extraordinary feat was achieved. During the main phase of the mission, Rosetta accompanied the comet through perihelion (13 August 2015) until the end of the mission (30 September 2016).

Mission facts

Rosetta is named after the Rosetta stone, which helped scholars decipher hieroglyphics used in ancient Egypt. Just like its namesake, the spacecraft helped to unravel the mysteries of the past.

The Rosetta mission involved a number of significant ‘firsts’. It was the first spacecraft to:

  • orbit a comet’s nucleus
  • fly alongside a comet as it heads towards the inner Solar System
  • examine from close proximity how a frozen comet is transformed by the warmth of the Sun
  • use the gravitational pull of Earth (three times) and Mars (once) to propel itself towards its final destination
  • the second Earth swing-by took place in November 2007, and its final Earth swing-by occurred in November 2009
  • many of the manoeuvres Rosetta performed during its journey are so complex that there was absolutely no room for error for the team controlling the spacecraft

Technology

The Rosetta mission consisted of an orbiter and a small lander. Between them, they carried a total of 20 scientific instruments.

Orbiter

The orbiter was centred around a large aluminium structure (2.8 x 2.1 x 2 m). It contained 11 instruments which enabled scientists to build up a clear picture of the comet’s nature. The mission ended when the orbiter was put into a controlled impact onto the comet.

Lander

The small (100kg) Philae lander was carried on the side of the orbiter until it arrives at Comet 67P Churyumov-Gerasimenko.

Once the orbiter was aligned correctly, the lander was commanded to self-eject from the main spacecraft and unfold its three legs to prepare for a gentle touchdown.

Immediately after touchdown, the lander was unable to secure itself to the hard cometary surface and bounced coming to rest in a different location to the one planned. This left Philae at an angle by a cliff and the solar panels were unable to power the lander. Although not all of the planned science was carried out, all of the 10 instruments did operate and returned new and exciting data.

UK involvement

Rosetta had significant UK involvement from industry and academia.

One of the main challenges for all the companies designing instruments for Rosetta has been to ensure the components remain intact for ten years, while the spacecraft makes its way to the comet, and then work perfectly when it gets there. Not an easy task!

Airbus Defence and Space, based in Stevenage, was the major subcontractor for the Rosetta platform. AEA Battery Systems Limited provided innovative batteries for the spacecraft and lander. These are smaller, lighter and much more reliable than the traditional nickel-cadmium batteries.

AEA Technology, European Space Tribology Laboratory (ESTL) developed the Micro-Imaging Dust Analysis System (MIDAS).

Technology created by Logica helped to explore some of the issues involved in such a long mission. The company was also involved in the development of the Rosetta on board software. Polyflex Space Ltd provided tanks to store the helium used by the lander.

SciSys UK Ltd was responsible for the spacecraft Mission Control System development and maintenance. In recognition of this work on the Rosetta and the Beagle 2 missions, SciSys were awarded the title of “Innovator of the Year” by the UK Computing Awards for Excellence 2004.

Surrey Satellite Technology Limited (SSTL) designed a wheel that will stabilise the probe as it descends and lands on the comet.

VEGA Group plc was involved in many aspects of the Rosetta mission, from the overall design of the spacecraft to the on board software.

UK scientists were involved in ten of the 21 experiments that Rosetta and Philae carried out during the mission. The Open University leading the team for Ptolemy, a gas analyser instrument on the lander. Together with the Science & Technology Facilities Council (STFC) Rutherford Appleton Laboratory, they managed to reduce a lab full of chemistry equipment to enable it to fit into a space the size of a shoebox.

Imperial College London and University College London’s Mullard Space Science Laboratory (MSSL) supplied a team studying the comet’s plasma as part of the Rosetta Plasma Consortium (RPC) on the orbiter. The RPC examined the structure of the comet, monitored its behaviour and studied how it interacts with particles in the solar wind - the stream of charged particles coming from the Sun.

Armagh Observatory helped to analyse the results from the OSIRIS instrument.

Scientists at Oxford University were part of the science team for VIRTIS.

Queen Mary College at the University of London investigated the results of the CONSERT instrument.

Published 28 April 2014
Last updated 21 December 2018 + show all updates
  1. Mission information updated.
  2. First published.