Rosetta

                                ROSETTA 

                ESA's historic Rosetta mission concluded as planned, on 30 September 2016, with a controlled impact onto the comet it had been investigating for more than two years. The mission was launched on 2 March 2004, on a 10-year journey towards comet 67P/Churyumov-Gerasimenko. En route, it passed by two asteroids, 2867 Steins (in 2008) and 21 Lutetia (in 2010), before entering deep-space hibernation mode in June 2011. On 20 January 2014, it 'woke up' and prepared for arrival at the comet in August that year. On 12 November, the mission deployed its Philae probe to the comet, the first time in history that such an extraordinary feat was achieved. During the next phase of the mission, Rosetta accompanied the comet through perihelion (13 August 2015) until the end of the mission. 

 Mission to Catch a Comet!

Comets have inspired awe and wonder since the dawn of history. Many scientists today believe that comets crashed into Earth in its formative period spewing organic molecules that were crucial to the growth of life. Comets may have formed about the same time as the giant planets of our solar system (Jupiter, Saturn, Uranus, and Neptune) - about 4.6 billion years ago. Some scientists think that comets and planets were both made from the same clumps of dust and ice that spewed from our Sun’s birth; others think that these roving time capsules are even older than that, and that they may contain grains of interstellar stuff that is even older than our solar system!

Attempting New “Firsts” in Space

Rosetta is a spacecraft on a ten-year mission to catch the comet "67P/Churyumov-Gerasimenko" (C-G) and answer some of our questions about comets. Rosetta will be the first spacecraft to soft-land a robot on a comet! Rosetta will also be the first spacecraft to accompany a comet as it enters our inner solar system, observing at close range how the comet changes as the Sun’s heat transforms it into the luminous apparition that has frightened and inspired people for centuries.

Named after the Rosetta Stone

The Rosetta spacecraft is named after the ancient Rosetta Stone that you can visit today in London’s British Museum. The Philae lander is named after the Philae Obelisk which, together with the Rosetta Stone, provided the key to our first understanding of Egyptian hieroglyphs, or “picture words.” Scientists hope that the Rosetta spacecraft will enable us to translate the even older language of comets, as expressed by their thermal signatures, into new knowledge about the origins of our solar system and, perhaps, life on Earth.

An International Mission with U.S. Support

This daring international mission is spearheaded by the European Space Agency (ESA), with key support and instruments from NASA. NASA contributed three of the orbiter's instruments (ALICE, MIRO, and IES) and part of the electronics package for the Double Focusing Mass Spectrometer - one of two detectors on the Swiss ROSINA instrument. NASA is also providing science investigators for selected non-U.S. instruments. In all, NASA is involved to a greater or lesser degree in Alice, MIRO, IES, OSIRIS, Radio Science, ROSINA, and VIRTIS experiments. NASA's Deep Space Network provides support for ESA's Ground Station Network for spacecraft tracking and navigation.

Schedule of Events

ESA’s Science Programme Committee approved the International Rosetta Mission in November 1993 as a Cornerstone Mission in ESA's Horizons 2000 science program.
On March 2, 2004, Rosetta was launched into an orbit that enabled it to chase Earth around the Sun for about a year.

• On March 4, 2005, Rosetta caught up with Earth and executed the first of its four gravity assists (three from Earth and one from Mars). This first gravity assist hurled Rosetta toward Mars for its meeting in 2007.
• En route to Mars, Rosetta's instruments analyzed the collision between Deep Impact's impactor and comet Tempel-1 on July 4, 2005.
• In February 2007, Rosetta executed a close flyby of Mars, which provided the gravity assist it needed to loop back toward Earth for a second flyby in November 2007.
• In November 2007, Rosetta executed its second Earth flyby, gaining the gravity assist it needed to pass Mars' orbit and reach the asteroid belt.
• On September 5, 2008, Rosetta passed within 1700 km of asteroid Steins, enabling its instruments to closely observe the flying rock.
• In November, 2009, Rosetta swung back for a final boost from Earth’s gravity to return again to the asteroid belt.
• On July 10, 2010, Rosetta flew within 3000 km of asteroid Lutetia, and again used its instruments to observe at close range this asteroid, ten times larger than Steins.
• By May, 2011, Rosetta was coasting through areas in the outer solar system where the sun is almost a billion km away. At that distance, Rosetta’s solar panels are not able to gather much energy from the Sun, so the spacecraft shut down most electrical activities and will hibernate until comet C-G returns from its long transit in the outer solar system.
• In January 2014, Rosetta will fire its engine to position itself next to comet C-G in May 2014 as it comes hurtling by. Rosetta will release the Philae for a controlled soft landing on the comet. The Philae will then transmit critical data from the comet’s surface for relay back to Earth. Philae will use harpoons to anchor itself to the comet.
• After escorting comet C-G past its perihelion (closest point to the Sun), Rosetta will terminate its mission.

Mission Goals

Primary Mission Goals

• Catch comet 67P/Churyumov-Gerasimenko in 2014 and accompany it into the interior solar system.
• Observe the comet's nucleus and coma from close range.
• Deploy Philae to make first controlled landing on a comet.
• Measure the increase in cometary activity during perihelion (position closest to the Sun).
• Observe the changes associated with the change in season as the comet leaves the inner solar system on its outbound leg. At that time a different pole will be exposed to the sun.

Other Goals En Route to Comet C-G

• Assist in observation of Deep Impact Mission (Comet Tempel-1) (2005)
• Observe Mars during Mars Gravity Assist maneuver (2007)
• Observe two asteroids: Steins (2008) and Lutetia (2010)

Mission Name

Rosetta is named after the Rosetta Stone, an incomplete stela of black basalt incised with the same priestly decree in three scripts (Egyptian Hieroglyphs, Egyptian Demotic and Greek) concerning Ptolemy V. The great significance of the Stone is that it provided the key to deciphering Egyptian hieroglyphs. The Rosetta Space Mission seeks to see if comet C-G can provide a key to deciphering the origins of the solar system and/or life on Earth.

 

NASA's Role

NASA has contributed three instruments to Rosetta - ALICE, MIRO, and IES - plus a significant portion of the electronics package for another instrument, ROSINA. ALICE , MIRO, and IES will provide information about the dynamics of comet C-G: how it develops its coma and tails, and how its chemicals interact with each other, and with radiation and the solar wind.

ALICE will map the comet’s nucleus for pockets of both dust and ice. MIRO and ROSINA will examine the vicinity for signs of water coming off the nucleus. MIRO will do it remotely, and ROSINA will do it by waiting for particles to actually hit the detectors. IES will look for examples of direct interaction between the solar wind and the nucleus.

ALICE may also help scientists learn more about the origin of the comet and what its interstellar material can tell us about the origin of our solar system. While ALICE and MIRO detect uncharged atoms and molecules, IES will detect their charged counterparts - ions - as well as electrons.

ALICE is an ultraviolet spectrometer, and MIRO is the Microwave Instrument for the Rosetta Orbiter. Both are remote-sensing instruments that will be used to explore the comet's physical characteristics, including how its structure and composition change over time as it travels toward the Sun. ALICE and MIRO can detect invisible electromagnetic waves (ultraviolet and microwave ranges) associated with objects far away, just as people can see visible light from stars light years away. En route to comet C-G in 2005, ALICE and MIRO explored comet Tempel-1 from about 46 million miles away, participating in NASA’s Deep Impact experiment. ALICE will also be the first ultraviolet spectrometer to study a comet at close range. ALICE can detect a wide range of molecules and atoms, but will leave the charged particles (ions and electrons) to IES.

MIRO is the first microwave instrument to fly in space and explore celestial bodies. As both spectrometer and radiometer, it can detect temperature as it identifies chemicals. Perhaps most important, MIRO can see and measure its target molecules even when ALICE and other instruments are blinded by dust. The microwaves that MIRO detects can penetrate dusty environments that block the visible and ultraviolet ranges of light.

IES (Ion and Electron Sensor) detects the presence and energy of ions and electrons in the comet and asteroid environments. It is an in situ (in place) instrument, meaning that it must directly contact ions and electrons to measure them, just as we must directly contact perfume molecules to identify their scent. For this reason, IES had no role in the Deep Impact experiment because it took place 46 million miles from Rosetta. ALICE and MIRO, being remote-sensing instruments, were able to observe Deep Impact. During the Earth and Mars flybys, however, IES collected data on both ion and electron masses and energies in those planets' magnetospheres, and it will be "in situ" for the asteroid flybys as well.

Working Together

The scientific missions for these instruments, and others on Rosetta, sometimes overlap. For example, ALICE and MIRO, and some other instruments will observe some of the same chemicals. Studying the same things with different instruments and at different wavelengths of light can lead to two outcomes: corroboration, when all the instruments agree on what they see, or conflict, when they disagree. Both outcomes are useful to scientists. Corroboration enables scientists to accept their results with greater confidence than if they used only one instrument. If conflicts arise, however, they must find the reason. And that can lead to the discovery of new science.