International Ultraviolet Explorer (IUE)

Ultraviolet observations of the Universe

  • Completed
  • Launched 26 January 1978
  • Ended September 1996
The International Ultraviolet Explorer (IUE) has been one of the most productive satellites ever built. IUE provided invaluable information about stars located millions of kilometres away as well as objects much closer to home, such as comets approaching our part of the Solar System.

IUE was originally planned as a three to five year mission to analyse ultraviolet light from the stars. By the time it was eventually shut down, more than 18 years later, it had lasted six times as long as originally planned.

The International Ultraviolet Explorer did not produce images but measured the energies of ultraviolet rays coming from celestial objects, giving insight into the physical conditions in those objects.

IUE's best known observation was of Halley's Comet when it visited Earth in 1986. The satellite was also central to the extensive programme of observations of Jupiter’s atmosphere during the impact of Comet Shoemaker-Levy in 1994.

Although it did not capture the public imagination in the way that Hubble has, IUE remains one of the most successful missions of all time. Scientists still use data gathered by the satellite, more than a decade after the mission ended.

Mission facts

  • IUE was a joint mission between ESA and NASA with UK involvement.

  • For 18 years, the satellite made one hour long observation every 90 minutes, making it one of the most productive missions in the history of space exploration.

  • The mission was the precursor of more recent observatories in space, such as Hubble.

  • Archived data from IUE was the first from any mission to be made available online. This was back in 1985, before the invention of the World Wide Web.


Each of the three partners was responsible for a key part of IUE

NASA provided the spacecraft, two of the instruments and one ground observatory. ESA provided the solar panels and the second observatory. The UK supplied detectors and sensors.

The reliability of IUE's operation throughout its 18 years in space was remarkable. Although the back-up cameras developed a fault, the primary cameras remained fully operational. And despite the failure of four of its six gyroscopes, control of the satellite’s position remained precise to the last.

UK involvement

As one of the three main partners, the UK had strong involvement in the design, instruments and science of the mission.

Apollo Relic Reveals its Secrets

Imagine landing on the Moon, climbing down the ladder of your spacecraft, and looking around the harsh lunar landscape—to see another, older spacecraft standing only 200 yards away.

That's exactly what happened in November 1969, when astronauts Pete Conrad and Alan Bean stepped out of the Apollo 12 lunar module. There, within walking distance on the edge of a small crater, stood Surveyor 3, an unmanned U.S. spacecraft that had landed in April 1967.

Apollo 12's landing site had been chosen deliberately near Surveyor 3. The little lander had spent two and a half years exposed to the worst the Moon had to offer: harsh vacuum, intense cosmic radiation, meteoritic bombardment, extreme temperature swings. Back on Earth, NASA engineers wanted to know how metals, glass and other spacecraft building materials held up to that kind of punishment. Inspecting Surveyor 3 first hand seemed a good way to find out.

On their second four-hour EVA, Bean and Conrad walked over to Surveyor 3, took dozens of photographs and measurements, and began snipping off parts of metal tubing and electrical cables. They retrieved a camera. The very last thing they removed was a small scoop at the end of Surveyor's extendable arm, which had dug into the dry moon dust and gravel to make mechanical measurements of lunar soil.

The little scoop, the camera, and other artifacts returned to Earth were analyzed and then put in storage. At some point in the intervening four decades, the scoop, owned by Johnson Space Center, was transferred on permanent loan to a space museum in Kansas. And there matters quietly lay ... until recently when researchers at NASA's Glenn Research Center (GRC) realized that that little scoop could hold big secrets.

Namely, the secrets of digging on the Moon.

NASA is returning to the Moon with plans to establish an outpost--and this will inevitably require some digging. The rocky, dusty lunar soil or "regolith" contains many of the natural resources humans need to live. For instance, there is plentiful oxygen bound up in ordinary moon rocks and, in polar regions, deposits of frozen water may lie hidden in the soil of shadowed craters. All that's required is a little excavation.

"To design lunar digging equipment, we need to predict the forces required to move a scoop or other implement through lunar regolith," says Allen Wilkinson, team leader of the ISRU (In-Situ Resource Utilization) Regolith Characterization team at the Glenn Research Center.

Surveyor 3 and a sister ship Surveyor 7 actually dug into the Moon and measured how hard their drive motors had to work to scoop, press, and scrape the soil. To interpret those measurements more than 40 years later, however, Wilkinson's team needs to know the dimensions of the Surveyor scoops. Unfortunately, they learned, the blueprints had been lost! Only a scoop itself could provide the answer.

That sent Wilkinson to Hutchinson, Kansas, in April 2007 to borrow the Surveyor 3 scoop from the Kansas State Cosmosphere in order to make detailed measurements.

Measuring the scoop, however, would prove to be no simple matter. You can't just lay a ruler along the scoop and read off the dimensions. Indeed, you can't touch it at all. The Surveyor 3 scoop is in an airtight triangular container, and NASA curators do not wish the scoop to be removed because handling in air will degrade the historical fidelity of the unique artifact.

So the Glenn team borrowed photogrammetry apparatus from the Kennedy Space Center. Photogrammetry is a technique of measuring objects strictly from photographs. They have a photographic studio setup with a white background. GRC team member Juan Agui, an expert in digging force experiments, photographed the scoop in its container next to a standard photogrammetry cube, which has a precise checkerboard pattern on it. Then, using software, Robert Mueller of the Kennedy Space Center extracted dimensions using mathematical triangulation, measuring from points on the scoop to points where corners of dark checks meet on the cube. The software was developed for the Columbia Accident Investigation Board activity.

"Photogrammetry is pretty good," Agui remarks. "We got measurements of the scoop accurate to 0.030 or 0.040 inch (~1 mm)."

They've since constructed a replica of the scoop and now they are using it to dig into simulated lunar regolith.

"Measurements of digging forces are underway," he says. The replicated scoop plunges into a rectangular "soil bed" filled with JSC-1a, a man-made moondust substitute that closely matches the known properties of lunar regolith, while a computer monitors bearing forces. "Our team is quite pleased to find that the measurements appear to be close to reproducing [the best] Surveyor 7 data from the Moon."

With this test bed in place, the team can, e.g., move forward to test alternate scoop designs and refine theories of lunar soil mechanics. "Obtaining the Surveyor replica really made the difference," says Agui.

The secrets of digging on the Moon are being revealed.Read more...>

International GammaRay Astrophysics Lab (INTEGRAL)

Detecting high energy radiation

  • In operation
  • Launched 17 October 2002
  • Due to end 31 December 2012
The International Gamma Ray Astrophysics Laboratory (INTEGRAL) is providing new insights into the most violent and exotic objects of the Universe, such as black holes, neutron stars, active galactic nuclei and supernovae. The mission is led by the European Space Agency (ESA) in co-operation with Russia, the United States, the Czech Republic and Poland.

INTEGRAL is the most sensitive gamma ray observatory ever launched and continues to change the way astronomers think of the cosmos. It is the first space observatory that can see visible light, X-rays and gamma rays at the same time.

Gamma rays are even more energetic than X-rays and much more penetrating. Fortunately, the Earth's atmosphere acts as a shield to protect us from any harmful effects of gamma rays. The downside of this is that we can only see them from space.

Gamma rays can also appear as brief explosions of radiation, known as gamma ray bursts. These short bursts create vast amounts of radiation but at the moment scientists don't know what is exploding. INTEGRAL and NASA’s Swift mission are helping us to understand these phenomena.

Thanks to INTEGRAL, we now know that more than 400 objects in space emit detectable gamma rays. After more than five years in space, INTEGRAL’s other achievements include the discovery of more than 100 ‘super-massive’ black holes and stars so deeply enveloped in dust and gas that other telescopes cannot see them. With more than 70% of the sky now observed by the spacecraft, astronomers have been able to construct a catalogue of celestial gamma ray sources.

Mission facts

  • INTEGRAL employs much of the same spacecraft engineering as ESA's X-ray satellite XMM-Newton. This meant considerable amounts of money were saved in building the satellite.

  • The satellite orbits Earth once every 72 hours. It spends most of its orbit at least 40,000 kms outside Earth's radiation belts. This reduces interference from background radiation.

  • In November 2007, because the mission has been so successful, ESA’s Science Programme Committee unanimously approved an extension of the mission from 2010 to 2012.


Gamma rays from distant objects are relatively rare and difficult to observe. With their penetrating power they cannot be focused by conventional mirrors or lenses so special detectors and imaging systems had to be designed.

The four scientific instruments in INTEGRAL’s payload weigh a massive 2,000 kg. Two instruments are designed to both create images and measure the energy of gamma rays. Two other instruments provide simultaneous imaging of the same sky region in X-rays and optical light.

UK involvement

Researchers at the University of Southampton were among those who originally proposed the mission. They are also leading the compilation of the celestial gamma ray catalogue.

Infrared Space Observatory (ISO)

Exploring the hidden depths of space

  • Completed
  • Launched 17 November 1995
  • Ended in 1998
When it was launched in 1995, the Infrared Space Observatory (ISO) was the most sensitive infrared satellite ever sent into space. ISO has enabled us to peer into regions of space invisible to other telescopes, penetrating dust clouds to observe new stars as they form and detect distant young galaxies.

The satellite made important studies of cool objects in the Universe that emit infrared radiation but no visible light. Infrared radiation is primarily heat, or thermal radiation. Even objects that we think of as being very cold (such as an ice cube) emit infrared radiation.

During its 28 months in orbit, the satellite completed 900 revolutions of the Earth and made 30,000 different scientific observations. Data from the mission is still being used by scientists today.

Mission facts

  • ISO was originally designed to last 18 months but a combination of some world-class engineering and a bit of luck meant it actually lasted for 28 months, and generated far more data than expected.

  • On average, ISO made 45 scientific observations each time it went around the Earth. Each orbit lasted just under 24 hours.

  • To observe the cool part of the Universe, ISO's instruments needed to work at -269 °C, close to absolute zero (-273 °C). Scientists used a coolant of liquid helium to maintain these temperatures throughout the mission. This made ISO one of the coldest objects in the universe.

  • The mission ended soon after the coolant ran out in April 1998. The satellite is now heading towards the Earth’s atmosphere, where it will burn up in about 2014.


Scientists from 11 European countries helped to design the four scientific instruments used by ISO.

A telescope with a 60 cm diameter primary mirror fed infrared light via a pyramidal mirror to the four instruments.

Between them, the instruments made observations at a wide range of wavelengths. This meant they could measure and produce images of many different types of astronomical object.

UK involvement

UK scientists led the development of one instrument and were involved in the development of three of the four instruments used by ISO. The STFC Rutherford Appleton Laboratory was involved in collating the data from the mission.

Hipparcos, The Space Mission

Europe’s pioneering star mapping mission
  • Completed
  • Launched 8 August 1989
  • Ended August 1993
  • Results updated 2007
During its three and a half year mission, Hipparcos pinpointed the positions, and measured distances, of more than 100,000 stars with an accuracy that had never been achieved before.

Hipparcos was the first mission dedicated to measuring the positions and motions of stars. This branch of astronomy is known as astrometry. In the process, Hipparcos also measured the brightness and colours of the stars it mapped. It is the predecessor of ESA's Gaia mission, due for launch in 2011.

As well as giving a 3-D picture of the distances between stars close to our Solar System, data from the satellite was also used to confirm the value of a basic parameter in Einstein’s Theory of General Relativity, describing the bending of light around the Sun.

The data from Hipparcos was originally published in a catalogue released in May 1997. Thanks to recent advances in computational processing power and extensive investigations of the Hipparcos data, it has been possible to revisit the original data and significantly improve the accuracy of the derived catalogue.

The latest catalogue from the mission went online in January 2008.

Mission facts

  • The satellite was named after Hipparchus of Rhodes, a Greek mathematician and astronomer who lived from 190 to 120 BC. Hipparchus is known as a ‘father’ of astronomy for his work in classifying stars into six categories of brightness known as Magnitudes.

  • At its time of operation, the Hipparcos spacecraft gathered more data than any previous project in the history of astronomy. Its successor, the Gaia mission, is designed to produce data 10 to 100 times more accurate, and for 10,000 more objects, collecting altogether over one thousand times more data during its five year mission.


While in orbit, the 1.1 tonne satellite turned slowly on its axis to see every part of the sky at least twice every six months, scanning it in at least two different directions.

Each star was measured on average 115 times over the mission.

By observing the sky through two telescope apertures simultaneously, it was possible to derive accurate positions for more than 50,000 stars.

UK involvement

Representatives from the Royal Greenwich Observatory, now based within the Institute of Astronomy, part of the University of Cambridge, were an essential part of one of the two data processing consortia that worked on the original data and contributed to the Hipparcos data catalogue released in 1997.

Hinode, Japanese mission.

Japanese mission to investigate the Sun
  • Launched on 22 September 2006
  • Mission due to end in 2009
  • UK and international involvement
The Japanese Hinode mission is studying the processes involved in solar flares and Coronal Mass Ejections. These events send billions of tonnes of particles spewing out into space and can have a major effect on the Earth.

Solar flares are tremendous explosions in the atmosphere of the star. They can directly affect the Earth’s upper atmosphere disrupting radio communications.

Coronal Mass Ejections can trigger a disturbance of the Earth's magnetic field called a geomagnetic storm. Large geomagnetic storms can knock-out orbiting satellites. Coronal Mass Ejections drive shock waves of energetic particles outwards from the Sun that could injure astronauts working in orbit.

Designed and built by teams in the US, Japan and the UK, Hinode has key involvement from University College London’s Mullard Space Science Laboratory (MSSL) and the STFC Rutherford Appleton Laboratory (RAL).

For more information, visit the ESA Hinode pages.

Mission facts

  • Hinode was originally known as Solar-B but was renamed Hinode, meaning sunrise in Japanese, after its launch.

  • The spacecraft can distinguish between steady movements on the Sun's surface and the changes that take place in the build-up to a solar flare.

  • The mission is operating in conjunction with SOHO and STEREO. Together with Ulysses these three missions are providing an unprecedented examination of our nearest star.


There are three instruments on board Hinode, designed to explore the trigger for solar flares.

The Solar Optical Telescope is the first large optical telescope flown in space dedicated to observing the Sun.

The UK is leading the EUV Imaging Spectrometer (EIS) science team. EUV stands for Extreme Ultraviolet. This instrument was designed and developed by an international team led by MSSL.

The primary function of the EIS is to measure the speed, density and temperature of particles coming from the Sun.

The third instrument, an X-ray telescope, is providing images of the Sun’s outer layer, the corona, at different temperatures.

Through the Science and Technology Facilities Council, the UK has invested almost £5 million in developing and building the EIS. Led by a team from MSSL, RAL provided the calibration and observing software. The University of Birmingham was also involved in the build.

Gaia, A mission to map the stars and their movements.

A mission to map the stars and their movements

  • In development since 2007
  • Due to launch in 2011

The European Space Agency’s Gaia mission will examine the Milky Way in unprecedented 3-D detail.

The spacecraft will survey more than one billion stars to make the largest, most precise map of our Galaxy to date. Gaia will be scanning the sky continuously for five years. This will enable each object to be observed on average about 80 times. Gaia will log the position, brightness and colour of every celestial object of sufficient brightness that falls within its field of view. Gaia will be using the same principle of measurements that was successfully employed by the Hipparcos mission.

The repeated observations will allow astronomers to calculate positions, distances and velocities relative to the Sun for the objects that are observed. Any variations in brightness will also be followed and analysed. With this wealth of data, astronomers will be able to get a better understanding of the history and evolution of our Galaxy.

Gaia will also be able to detect large numbers of double stars throughout the Milky Way, as well as nearby planets that are the same size - or bigger - than Jupiter. It will do this by measuring small disturbances in the positions of stars caused by a planet's gravitational field. Scientists predict Gaia could find up to 50,000 planets during its five-year mission!

Mission facts

  • Gaia originally stood for Global Astrometric Interferometer for Astrophysics. As the project evolved, the double-interferometer concept was replaced with different instruments. However, the mission name remained even though it no longer uses an interferometer as part of its telescope design.

  • The measurement accuracy expected for Gaia will be about 10 to 100 times greater than what was achieved for the Hipparcos mission. The number of objects observed will be 10,000 times greater.

  • As part of its mission, Gaia is expected to detect tens of thousands of stars that failed to ignite. These are known as brown dwarves. The information gathered will help scientists understand the formation of stars.


Gaia will be equipped with two telescopes, projecting images onto a single integrated instrument. This will be able to record the position, brightness and colour of the objects under observation.

The spacecraft will be equipped with a ‘micro propulsion’ system, allowing fine adjustments to be made to its position.

UK involvement

The data processing for the mission involves pan-European collaboration, with significant leadership from the UK.

Within the UK, the Universities of Cambridge, Leicester, Edinburgh and Brunel are involved in data processing, along with the STFC Rutherford Appleton Laboratory and University College London’s Mullard Space Science Laboratory (MSSL).

A number of UK research groups and industrial partners such as MSSL and the Universities of Leicester and Cambridge have been involved in the design phase of the instruments on board Gaia.

ExoMars, Europe’s mission to Mars

ExoMars is part of ESA’s Aurora programmeand lays the foundation for future human exploration of the Solar System.

Its aim is to examine the biological environment on Mars in preparation for other robotic missions and possible human exploration. Data from the mission will also provide invaluable input for broader studies of geochemistry, environmental science and exobiology-the search for life on other planets.

ExoMars will consist of an orbiter, a descent module and a six wheeled rover. The first European rover on Mars will carry a drill that can burrow up to 2 m into the Martian surface allowing its scientific instruments to analyse and sample the soil and search for mineral content, composition and traces of past and present life.

Mission facts

  • The rover’s Pasteur payload will be devoted to exobiology - the search for evidence of life on Mars, past or present - and geochemistry.

  • The lander will include a package RPT devoted to studies of geophysics and environmental science.

  • Mission control will be at the European Space Agency Operations Centre (ESOC) in Darmstadt, Germany.

  • ExoMars will influence whether Europe contributes to the future Mars Sample Return mission.


The rover will roam around the Martian surface by using electrical power generated from its solar arrays.

The rover’s software will have a degree of ‘intelligence’ and autonomy to make certain decisions on the ground and will navigate using optical sensors.

PanCam (The Panoramic Camera System) will provide 3-D imagery of the surface and provide context for the life detection experiments.

The GEP (Geophysical and Environmental Package) will characterise the Martian environment at the landing site.

An environmental package will provide data on the planet’s UV and ionising radiation, dust, humidity and meteorology.

UK involvement

Astrium Limited is building the rover and there is considerable involvement from a number of academic institutions with the on board instruments.

UK involvement on the rover is considerable:

PanCam is led by the UK with scientists from University College London’s Mullard Space Science Laboratory (MSSL) working with the University of Aberystwyth, Birkbeck College and Leicester University. The wide angle stereo camera will provide stereo information and enable the concentration of water vapour to be measured.

Brunel University, Bradford University and BNSC partner, STFC Rutherford Appleton Laboratory, are key players in the development of the CCD camera on the Raman-LIBS (Laser-Induced Breakdown Spectrometer) which can detect the presence of past or present life on Mars.

Scientists from Brunel and Leicester Universities also provided the X-ray CCD detectors on the X-Ray Diffractometer which will identify the mineral content of rock samples.

Imperial College London is developing techniques for sample extraction and analysis that will help with the design of the Mars Organics and Oxidants Detector.

The UK-led LMC (Life Marker Chip) instrument will search for specific molecules associated with life. Scientists from Cranfield University and the University of Leicester helped develop the chip. UVIS (the UV-VIS Spectrometer for ultra violet and visible light) is also UK-led at The Open University. It is part of the GEP and will measure the UV and visible spectrum on the planet.

AEP, the Meteorological or Advanced Environmental Package, is suite of UK-led instruments involving the Open University together with the University of Oxford. These instruments will measure pressure, temperature, wind speed, direction and sound.

SEIS (Seismic System) contains a microseismometer element provided by Imperial College London (ICL). The instrument will explore the internal structure of the planet and examine whether there is seismic activity within the large volcanic regions of Mars.

ICL is also providing the software for the magnetometer’s on board analysis and magnetic field detection.

Deep Impact, Mission

The first mission to look inside a comet

  • Launched 12 January 2005
  • The spacecraft’s impactor smashed into comet Tempel 1 on 4 July 2005
  • Deep Impact will fly-by comet Hartley 2 in December 2010
Deep Impact originally consisted of two spacecraft, one inside the other. It made a rendezvous with comet Tempel 1. Once in position, the smaller impactor craft separated from the larger spacecraft and was put on a collision course with the comet.

The resulting crash was not powerful enough to change the comet’s course. Instead it produced a large crater and scattered material from the comet into space. This allowed the fly-by craft and its on board instruments to successfully investigate beneath the surface of a comet for the first time.

Scientists are using these observations to better understand comets, the formation of our Solar System and also the possible implications of a comet on a collision course with Earth.

In July 2007, NASA gave both Deep Impact and Stardust new assignments and extended their missions. Deep Impact is now part of the EPOXI mission (Extrasolar Planet Observation and Deep Impact Extended Investigation).

Deep Impact is currently observing nearby bright stars and their giant orbiting planets. Direct observations will also allow scientists to find smaller, more Earth-like planets if gravity from these unseen alien worlds, or extrasolar planets, pulls on these transiting giant planets and affects their orbits.

Mission facts

  • Tempel 1, discovered by Ernst Tempel in 1867, orbits the Sun. It passes through the inner Solar System every five and a half years.

  • The washing machine-sized impactor travelled ten times faster than a speeding bullet shortly before it slammed into Tempel 1.

  • During Deep Impact’s fly-by of Earth, on 31 December 2007, the spacecraft observed the Moon, calibrated its instruments and used our planet’s gravity to assist it towards comet Hartley 2.


The fly-by craft used opitical imaging and infrared mapping technologies to analyse both the comet’s interior and the resulting debris from the crash. The instruments discovered water, microscopic dust, hydrocarbons and carbon dioxide ice.

HRI (High Resolution Instrument), MRI (Medium Resolution Instrument) and ITS (Impactor Targeting Sensor) guided the spacecraft towards the comet and took data readings before and after impact.

The impactor was made from 49 per cent copper to minimise the corruption of spectral emission lines used to analyse the comet nucleus or centre.

A camera on the impactor relayed images of the comet nucleus until seconds before the collision.

UK involvement

UK scientists from the University of Leicester, the Mullard Space Science Laboratory (MSSL) and the University of Cardiff were part of an international team that helped observe and study material ejected from the comet on impact.

The team used the Isaac Newton telescope on La Palma, Spain, to monitor the debris. The UK Schmidt telescope in Australia examined the colours of light emitted during the impact and NASA’s Swift satellite also watched the collision. Both Leicester and MSSL led instruments on Swift.

Chandrayaan-1, India’s first mission to the moon

India’s first mission to the moon

  • Due for launch 2008
  • An Indian Space Research Organisation (ISRO) mission

Chandrayaan-1 is India’s first unmanned mission to the Moon. It will spend two years performing high resolution mapping of the lunar surface in visible light, near infrared, low energy and high energy X-rays.

The spacecraft will also assess the Moon’s mineral resources and the distribution of elements such as silicon, iron and titanium.

Chandrayaan-1 is a 1.5 m cube and its scientific package contains two NASA, three European and seven Indian instruments. This includes a 30 kg Moon Impact Probe (MIP) which will be released from orbit to penetrate the lunar surface.

Its X-ray spectrometer (C1XS) is a further technical development on the D-CIXS instrument on-board the European Space Agency’s SMART-1.

NASA is providing the Moon Mineralogy Mapper (M3) and the Miniature Synthetic Aperture Radar (MiniSAR), which will be able to detect water ice up to a depth of several metres.

Mission facts

  • Chandrayaan-1 will be launched from a Polar Satellite Launch Vehicle in India.

  • The spacecraft weighs 523 kg and has similar design to the Kalpansat meteorological satellite.

  • There are 11 science payloads on board.

  • Chandrayaan is Hindi for ‘moon craft’.


A solar array will provide power for the spacecraft and generates 750 Watts.

The initial orbit will be 1,000 km, reducing to an eventual circular polar orbit of 100 km.

The Chandrayaan-1 Imaging X-ray Spectrometer (C1XS) is an X-ray fluorescence spectrometer which will be used to determine the composition of the Moon’s surface. Its main scientific objective is to map the amount of major rock-forming elements - such as magnesium, aluminium, silicon, titanium, calcium and iron - in the lunar crust.

The Terrain Mapping Camera (TMC) has a 5 m resolution.

UK involvement

The STFC Rutherford Appleton Laboratory designed and built the Chandrayaan-1 Imaging X-ray Spectrometer (C1XS) in collaboration with the Indian Space Research Organisation and the University of Helsinki.

The science team is chaired by Dr Ian Crawford from Birkbeck College, London, and the Principal Investigator is Prof Manuel Grande of the University of Wales, Aberystwth.

Cassini to Earth: 'Mission Accomplished, But New Questions Await!'

NASA's Cassini mission is closing one chapter of its journey at Saturn and embarking on a new one with a two-year mission that will address new questions and bring it closer to two of its most intriguing targets—Titan and Enceladus.

On June 30, Cassini completes its four-year prime mission and begins its extended mission, which was approved in April of this year.

Among other things, Cassini revealed the Earth-like world of Saturn's moon Titan and showed the potential habitability of another moon, Enceladus. These two worlds are primary targets in the two-year extended mission, dubbed the Cassini Equinox Mission. This time period also will allow for monitoring seasonal effects on Titan and Saturn, exploring new places within Saturn's magnetosphere, and observing the unique ring geometry of the Saturn equinox in August of 2009 when sunlight will pass directly through the plane of the rings.

"We've had a wonderful mission and a very eventful one in terms of the scientific discoveries we've made, and yet an uneventful one when it comes to the spacecraft behaving so well," said Bob Mitchell, Cassini program manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We are incredibly proud to have completed all of the objectives we set out to accomplish when we launched. We answered old questions and raised quite a few new ones and so our journey continues."

A new addition to the Cassini science team is Bob Pappalardo who will step into the role of Cassini Project Scientist in July, taking over for Dennis Matson, a multi-year veteran on the project who will be working on future flagship mission studies to the outer solar system. "I am honored and humbled to be able to work with such a scientifically rich mission, and with the outstanding scientists and engineers who are the backbone of Cassini," said Pappalardo.

Pappalardo is a geologist whose research focuses on processes that have shaped the icy moons of the outer solar system, including processes that power the geysers of Saturn's moon Enceladus. He received his bachelor's degree from Cornell University, Ithaca, N.Y., and his Ph.D. in geology from Arizona State University, Tempe. He worked with the Galileo imaging team while a Postdoctoral Researcher at Brown University, Providence, RI. Prior to joining JPL in 2006, he was an assistant professor of planetary sciences at the University of Colorado at Boulder. Currently he resides in Venice, Calif. More information on Pappalardo is at

Cassini launched Oct. 15, 1997, from Cape Canaveral, Fla., on a seven-year journey to Saturn, traversing 3.5 billion kilometers (2.2 billion miles). The mission entered Saturn's orbit on June 30, 2004, and began returning stunning data of Saturn's rings almost immediately. The spacecraft is extremely healthy and carries 12 instruments powered by three radioisotope thermoelectric generators. Data from Cassini's nominal and extended missions could lay the groundwork for possible future missions to Saturn, Titan or Enceladus.

Information about the Cassini Equinox Mission is at and

The Cassini Equinox Mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL.

Phoenix Poised to Deliver Sample for Wet Chemistry

NASA's Phoenix Mars Lander repositioned its robotic arm slightly today and is now poised to deliver Martian soil to its wet chemistry laboratory.

Sample delivery and analysis is planned as the science highlight tomorrow, June 25, the 30th Martian day of the mission. Phoenix is to perform the first-ever wet-chemistry experiment on polar Martian terrain, testing the soil for salts, acidity and other characteristics.

The wet chemistry laboratory is part of the suite of tools called the Microscopy, Electrochemistry and Conductivity Analyzer, or MECA.

The Phoenix mission is led by Peter Smith of The University of Arizona with project management at JPL and development partnership at Lockheed Martin, located in Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute. For more about Phoenix, visit:

Phoenix Scrapes to Icy Soil in Wonderland

NASA's Phoenix Mars Lander scraped to icy soil in the "Wonderland" area on Thursday, June 26, confirming that surface soil, subsurface soil and icy soil can be sampled at a single trench.

Phoenix scientists are now assured they have a complete soil-layer profile in Wonderland's "Snow White" extended trench.

By rasping to icy soil, the robotic arm on Phoenix proved it could flatten the layer where soil meets ice, exposing the icy flat surface below the soil. Scientists can now proceed with plans to scoop and scrape samples into Phoenix's various analytical instruments. Scientists will test samples to determine if some ice in the soil may have been liquid in the past during warmer climate cycles.

It's another encouraging step to meeting Phoenix mission goals, which are to study the history of Martian water in all its phases and determine if the Martian arctic soil could support life.

The Phoenix mission is led by Peter Smith of The University of Arizona with project management at JPL and development partnership at Lockheed Martin, located in Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute. For more information on the Phoenix mission, link to

Cassini-Huygens, The Mission

  • In operation
  • Launched 1997
  • Arrived at Saturn July 2004
  • Huygens probe landed on Titan 14 January 2005

Cassini-Huygens is the first mission to make a long-term study of Saturn, its moons, rings and complex magnetic environment. A joint NASA/European Space Agency (ESA)/Italian Space Agency project, Cassini-Huygens involves UK scientists on both the orbiter (Cassini) and probe (Huygens).

Since entering Saturn’s orbit, the spacecraft has transformed our understanding of the ringed planet. Achievements include the discovery of new rings and several new moons. Cassini has also witnessed a massive hurricane-like storm and found evidence that the planet’s rotation appears to be slowing. The spacecraft recently sent back views of the planet from high above and below these rings – a perspective never seen before.

Remarkable discoveries have been found among Saturn’s moons. The tiny moon, Enceladus, has spectacular jets of ice particles erupting from its south pole. Another moon, Phoebe, has turned out to be older than Saturn itself! The ‘black and white’ moon, Iapetus, was found to have a ridge along its equator higher than any mountain on Earth. The latest moon – the 60th – has been nicknamed ‘Frank’. It was spotted by Carl Murray from Queen Mary, University of London in collaboration with the Cassini imaging team.

Saturn’s largest moon, Titan, is a major focus of the mission. Titan has a very thick atmosphere - similar to Earth's when it was a very young planet. By studying Titan, scientists hope to gain an insight into how life might have first become established on Earth.

In January 2005, the Huygens probe descended by parachute through Titan’s atmosphere and survived for several hours on the surface. No-one knew whether to expect a hard or soft landing. In fact it was somewhere in between.

In March 2007, instruments on board Cassini found evidence of seas in the northern parts of Titan that might be filled with liquid methane or ethane. Results based on data from Huygens also suggest there is liquid methane rain on the planet.

Mission facts

  • The Cassini spacecraft is named after the Italian-French astronomer Jean-Dominique Cassini (1625 - 1712) who discovered four of Saturn's moons: Iapetus, Rhea, Tethys and Dione.

  • Huygens is named after the Dutch scientist Christiaan Huygens (1629 - 1695) who explained the nature of Saturn's rings and discovered its largest moon, Titan, in 1655.

  • Cassini-Huygens is as tall as a two-storey house and weighed 5,574 kg when it left the Earth.

  • The spacecraft travelled 3.5 billion km to reach its destination. Due to its weight and the distance it had to travel, Cassini-Huygens used a series of ‘gravity assists’ or ‘fly-bys’ on route to Saturn.

  • Gravity assist is a manoeuvre in which a spacecraft flies passed a planet. It works because of the mutual gravitational pull between the moving planet and a spacecraft. The planet pulls on the spacecraft but the spacecraft's own mass also pulls on the planet. This permits an exchange of energy. The fly-bys with Venus (twice) and Earth saved the equivalent of 68,000 kg of rocket fuel.


Cassini-Huygens has a total of 18 instruments equipped to investigate many different aspects of the Saturn system.


The Cassini Plasma Spectrometer (CAPS) measures the energy and electrical charge of particles like electrons and protons, to help us understand the nature of Saturn's magnetic field.

The Cosmic Dust Analyser (CDA) determines which elements make up the small dust particles around Saturn and how they interact with the planet's rings, moons and magnetic field.

The Composite Infrared Spectrometer (CIRS) provides vital information about Saturn and Titan's atmospheres. It has also been helping scientists identify the molecular composition of Titan's surface.

The Ion and Neutral Mass Spectrometer (INMS) is used to study Saturn's magnetic field and find out how gases around the planet's moons interact with the solar wind - the stream of charged particles coming from the Sun.

The Imaging Science Subsystem (ISS) has two optical cameras that have sent back tens of thousands of spectacular images.

The Dual Technique Magnetometer, or MAG, measures the interior structure and internal magnetic fields of Saturn and its moons, showing us how they interact with the particles that make up the solar wind.

The Magnetospheric Imaging Instrument (MIMI) has been taking images of Saturn’s hot plasmas: gases made up of ions, electrons and neutral particles.

The Radio Detection and Ranging Instrument (RADAR) is being used to create a map of Titan.

The Radio and Plasma Wave Science (RPWS) instrument measures radio and plasma waves given off by the solar wind as it comes into contact with Saturn's atmosphere and magnetic field. This is another experiment that helps scientists build up a clear picture of the planet, and what effect the Sun has on it.

The Radio Science Subsystem (RSS) measures how radio signals from Cassini change as they are sent through objects, such as Saturn's rings. This will give scientists detailed information on the structure of these objects.

The Ultraviolet Imaging Spectrograph (UVIS) measures the ultraviolet light being emitted from, and reflected off, Saturn's atmosphere, surfaces and rings. It will also tell scientists which elements make up the planet's atmosphere.

The two cameras on the Visible and Infrared Mapping Spectrometer (VIMS) are helping scientists determine the weather patterns on Saturn and Titan as well as the composition of the rings and moons.


As Huygens reached Titan, it switched itself on, activated its radio link to Cassini and began its descent into the atmosphere at around 20,000 km per hour.

As the first readings were collected, three sets of parachutes deployed to control its descent. Two and a half hours later, the first man-made object touched the Titanian surface.

Instruments on board Huygens measured the physical and electrical properties of the atmosphere and surface while a camera sent back images of the alien landscape.

Once it had landed, the probe was only designed to last around half an hour (at the most) before its batteries ran out. However, it is a testament to its construction that the Earth-based Parkes radio telescope was still receiving a signal more than three hours later.

UK involvement

The UK has been at the forefront of the design, engineering and science of Cassini-Huygens.

The Huygens Surface Science Package is led by the Open University (OU) with contributions from the STFC Rutherford Appleton Laboratory (RAL) and Southampton University.

The very first part of Huygens to touch Titan’s surface was a British-built sensor. The OU also has prime responsibility for the instrument that measured the probe’s deceleration through the upper atmosphere.

Imperial College London led the construction of the Dual Technique Magnetometer and analyses scientific data from the instrument, with input from Leicester University.

Queen Mary, University of London, helped in the design of the Imaging Science Subsystem and has a key role in the analysis of the images it is returning.

Oxford University was heavily involved in developing the hardware for the Composite Infrared Spectrometer, and is helping to analyse the data.

Cardiff University and again Queen Mary, University of London, helped to develop the infrared filters on the Composite Infrared Spectrometer.

University College London worked with RAL to develop part of the Cassini Plasma Spectrometer.

UK industry has also played a significant role with software provided by Logica and electronic testing and procurement co-ordinated by IGG component Technology.

IRVIN-GQ worked on the descent control system under contract to Martin Baker Space Systems. The latter was responsible for the parachute systems and the mechanisms needed to control the probe’s descent.

SciSys developed and maintained Huygens’ mission control system which monitored the probe’s health and controlled it billions of kilometres away on Earth.

All this technology had to operate flawlessly after seven years in the harsh space environment.

Phoenix Returns Treasure Trove for Science

NASA's Phoenix Mars Lander performed its first wet chemistry experiment on Martian soil flawlessly yesterday, returning a wealth of data that for Phoenix scientists was like winning the lottery.

"We are awash in chemistry data," said Michael Hecht of NASA's Jet Propulsion Laboratory, lead scientist for the Microscopy, Electrochemistry and Conductivity Analyzer, or MECA, instrument on Phoenix. "We're trying to understand what is the chemistry of wet soil on Mars, what's dissolved in it, how acidic or alkaline it is. With the results we received from Phoenix yesterday, we could begin to tell what aspects of the soil might support life."

"This is the first wet-chemical analysis ever done on Mars or any planet, other than Earth," said Phoenix co-investigator Sam Kounaves of Tufts University, science lead for the wet chemistry investigation.

About 80 percent of Phoenix's first, two-day wet chemistry experiment is now complete. Phoenix has three more wet-chemistry cells for use later in the mission.

"This soil appears to be a close analog to surface soils found in the upper dry valleys in Antarctica," Kouvanes said. "The alkalinity of the soil at this location is definitely striking. At this specific location, one-inch into the surface layer, the soil is very basic, with a pH of between eight and nine. We also found a variety of components of salts that we haven't had time to analyze and identify yet, but that include magnesium, sodium, potassium and chloride."

"This is more evidence for water because salts are there. We also found a reasonable number of nutrients, or chemicals needed by life as we know it," Kounaves said. "Over time, I've come to the conclusion that the amazing thing about Mars is not that it's an alien world, but that in many aspects, like mineralogy, it's very much like Earth."

Another analytical Phoenix instrument, the Thermal and Evolved-Gas Analyzer (TEGA), has baked its first soil sample to 1,000 degrees Celsius (1,800 degrees Fahrenheit). Never before has a soil sample from another world been baked to such high heat.

TEGA scientists have begun analyzing the gases released at a range of temperatures to identify the chemical make-up of soil and ice. Analysis is a complicated, weeks-long process.

But "the scientific data coming out of the instrument have been just spectacular," said Phoenix co-investigator William Boynton of the University of Arizona, lead TEGA scientist.

"At this point, we can say that the soil has clearly interacted with water in the past. We don't know whether that interaction occurred in this particular area in the northern polar region, or whether it might have happened elsewhere and blown up to this area as dust."

Leslie Tamppari, the Phoenix project scientist from JPL, tallied what Phoenix has accomplished during the first 30 Martian days of its mission, and outlined future plans.

The Stereo Surface Imager has by now completed about 55 percent of its three-color, 360-degree panorama of the Phoenix landing site, Tamppari said. Phoenix has analyzed two samples in its optical microscope as well as first samples in both TEGA and the wet chemistry laboratory. Phoenix has been collecting information daily on clouds, dust, winds, temperatures and pressures in the atmosphere, as well as taking first nighttime atmospheric measurements.

Lander cameras confirmed that white chunks exposed during trench digging were frozen water ice because they sublimated, or vaporized, over a few days. The Phoenix robotic arm dug and sampled, and will continue to dig and sample, at the 'Snow White' trench in the center of a polygon in the polygonal terrain.

"We believe this is the best place for creating a profile of the surface from the top down to the anticipated icy layer," Tamppari said. "This is the plan we wanted to do when we proposed the mission many years ago. We wanted a place just like this where we could sample the soil down to the possible ice layer."

The Phoenix mission is led by Peter Smith of The University of Arizona with project management at JPL and development partnership at Lockheed Martin, located in Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute. For more information on the Phoenix mission, link to

BepiColombo Space Craft

BepiColombo will be only the third spacecraft to visit Mercury in the history of space exploration. Mercury’s harsh environment makes it a particularly challenging mission. The spacecraft will have to endure intense sunlight and temperatures up to 350°C while gathering data.

This joint venture between Europe and Japan is an ESA ‘Cornerstone’ mission. It will help our understanding of the formation of the Solar System and its inner rocky planets, including Earth.

The mission will build on the experience gained in using electric propulsion on the SMART-1 mission. BepiColombo’s journey will also be helped by the gravity of the Moon, Earth and Venus during fly-bys to help it on its way to Mercury. It is due to arrive at the planet in 2019.

Mission facts

  • Mercury is the second smallest planet in the Solar System, larger only than Pluto (if you count Pluto as a planet) and not much bigger than our own Moon.

  • The surface is pock-marked with enormous craters caused by meteorites smashing into the planet’s surface in the early stages of the Solar System’s evolution some four billion years ago.

  • Although Mercury is only a third the size of Earth, it is almost as dense.

  • Scientists believe Mercury’s high density can be put down to the planet having a massive iron core.

  • The first mission to Mercury was NASA's Mariner 10 in 1974.

  • NASA's Mercury Messenger is currently on its way to Mercury and will arrive in 2011.

  • BepiColombo is named after Giuseppe ‘Bepi’ Colombo (1920-1984), a scientist who studied Mercury's orbital motion in detail as well as orbits and interplanetary travel in general.

  • It will take the BepiColombo spacecraft six years to reach its destination.

  • Although the temperature on Mercury can go as high as 462°C, the side of the planet facing away from the Sun is always very cold.

  • One of the key objectives for BepiColombo is to find out whether there is ice on the cold side of the planet.


BepiColombo will consist of three sections: a Mercury Transfer Module (MTM) – designed to get the spacecraft to the planet – and two orbiters: the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO).

Astrium Limited in the UK is responsible for the entire structure of the spacecraft.

ESA is responsible for the larger MPO. Its 11 scientific instruments will study Mercury from a low-polar-orbit.

UK space scientists, led by the University of Leicester, will develop one of the key instruments on board BepiColombo: MIXS (Mercury Imaging X-ray Spectrometer). MIXS will be used to help determine the composition of the planet’s surface.

MIXS will measure fluorescent X-rays that originate from the Sun and are reflected off the planet’s surface. Fluorescent X-ray measurements can be used to identify chemical elements while measurements at infrared wavelengths can be used to determine mineral composition.

Japan is developing the MMO. This will have five science instruments on board designed to examine Mercury’s magnetic field and magnetosphere – the magnetic ‘bubble’ surrounding a planet. Mercury intrigues scientists because it is hard to understand why such a small planet can have a magnetic field at all.

Once clear of Earth, BepiColombo will make its way to Mercury with an ion engine. This employs solar panels to generate electricity which is used to produce charged particles from xenon gas. A beam of these charged particles, or ions, is then expelled from the spacecraft. The engine will be used to slow the spacecraft down so that it can eventually be captured by the gravity of Mercury.

UK involvement

BepiColombo has significant UK involvement. Much of the spacecraft will be built in Britain in partnership with several UK science teams.

Astrium Limited has been appointed as the prime contractor to build the European components. In the UK, the company will provide all the spacecraft structures as well as the electrical and chemical propulsion systems for the MTM, the chemical propulsion system for the MPO (which will be the first dual mode propulsion system designed and built in Europe) and the systems which will separate the spacecraft modules on arrival at Mercury.

Scientists from the University of Leicester are leading work on the MIXS instrument. Researchers from STFC Rutherford Appleton Laboratory (RAL), the University of Lancaster, Open University and UCL's Mullard Space Science Laboratory are also involved in many aspects of the mission.

NASA Spacecraft Reveal Largest Crater in Solar System

New analysis of Mars' terrain using NASA spacecraft observations reveals what appears to be by far the largest impact crater ever found in the solar system.

NASA's Mars Reconnaissance Orbiter and Mars Global Surveyor have provided detailed information about the elevations and gravity of the Red Planet's northern and southern hemispheres. A new study using this information may solve one of the biggest remaining mysteries in the solar system: why does Mars have two strikingly different kinds of terrain in its northern and southern hemispheres? The huge crater is creating intense scientific interest.

The mystery of the two-faced nature of Mars has perplexed scientists since the first comprehensive images of the surface were beamed home by NASA spacecraft in the 1970s. The main hypotheses have been an ancient impact or some internal process related to the planet's molten subsurface layers. The impact idea, proposed in 1984, fell into disfavor because the basin's shape didn't seem to fit the expected round shape for a crater. The newer data is convincing some experts who doubted the impact scenario.

"We haven't proved the giant-impact hypothesis, but I think we've shifted the tide," said Jeffrey Andrews-Hanna, a postdoctoral researcher at the Massachusetts Institute of Technology in Cambridge.

Andrews-Hanna and co-authors Maria Zuber of MIT and Bruce Banerdt of NASA's Jet Propulsion Laboratory in Pasadena, Calif., report the new findings in the journal Nature this week. A giant northern basin that covers about 40 percent of Mars'surface, sometimes called the Borealis basin, is the remains of a colossal impact early in the solar system's formation, the new analysis suggests. At 5,300 miles across, it is about four times wider than the next-biggest impact basin known, the Hellas basin on southern Mars. An accompanying report calculates that the impacting object that produced the Borealis basin must have been about 1,200 miles across. That's larger than Pluto.

"This is an impressive result that has implications not only for the evolution of early Mars, but also for early Earth's formation," said Michael Meyer, the Mars chief scientist at NASA Headquarters in Washington.

This northern-hemisphere basin on Mars is one of the smoothest surfaces found in the solar system. The southern hemisphere is high, rough, heavily cratered terrain, which ranges from 2.5 to 5 miles higher in elevation than the basin floor.

Other giant impact basins have been discovered that are elliptical rather than circular. But it took a complex analysis of the Martian surface from NASA's two Mars orbiters to reveal the clear elliptical shape of Borealis basin, which is consistent with being an impact crater.

One complicating factor in revealing the elliptical shape of the basin was that after the time of the impact, which must have been at least 3.9 billion years ago, giant volcanoes formed along one part of the basin rim and created a huge region of high, rough terrain that obscures the basin's outlines. It took a combination of gravity data, which tend to reveal underlying structure, with data on current surface elevations to reconstruct a map of Mars elevations as they existed before the volcanoes erupted.