OrbitalHub

NASA dixit:

“July 26, 2009. The Cassini spacecraft eyes a prominent crater on the moon Janus. The south pole lies on the terminator at the bottom left of the image. This view is centered on terrain at 16 degrees south latitude, 64 degrees west longitude. This view looks toward the leading hemisphere of Janus (179 kilometers, or 111 miles across). North on Janus is up and rotated 31 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 98,000 kilometers (61,000 miles) from Janus and at a Sun-Janus-spacecraft, or phase, angle of 58 degrees. Image scale is 586 meters (1,922 feet) per pixel.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

ESA dixit:

“The ExoMars Rover, developed by ESA, provides key mission capabilities: surface mobility, subsurface drilling and automatic sample collection, processing, and distribution to instruments. It hosts a suite of analytical instruments dedicated to exobiology and geochemistry research: this is the Pasteur payload.

The Rover uses solar panels to generate the required electrical power, and is designed to survive the cold Martian nights with the help of novel batteries and heater units. Due to the infrequent communication opportunities, only 1 or 2 short sessions per sol (Martian day), the ExoMars Rover is highly autonomous. Scientists on Earth will designate target destinations on the basis of compressed stereo images acquired by the cameras mounted on the Rover mast.

The Rover must then calculate navigation solutions and safely travel approximately 100 m per sol. To achieve this, it creates digital maps from navigation stereo cameras and computes a suitable trajectory. Close-up collision avoidance cameras are used to ensure safety.

The locomotion is achieved through six wheels. Each wheel pair is suspended on an independently pivoted bogie (the articulated assembly holding the wheel drives), and each wheel can be independently steered and driven. All wheels can be individually pivoted to adjust the Rover height and angle with respect to the local surface, and to create a sort of walking ability, particularly useful in soft, non-cohesive soils like dunes. In addition, inclinometers and gyroscopes are used to enhance the motion control robustness. Finally, Sun sensors are utilised to determine the Rover’s absolute attitude on the Martian surface and the direction to Earth.

The camera system’s images, combined with ground penetrating radar data collected while travelling, will allow scientists on-ground to define suitable drilling locations.The Rover subsurface sampling device will then autonomously drill to the required depth (maximum 2 m) while investigating the borehole wall mineralogy, and collect a small sample. This sample will be delivered to the analytical laboratory in the heart of the vehicle. The laboratory hosts four different instruments and several support mechanisms. The sample will be crushed into a fine powder. By means of a dosing station the powder will then be presented to other instruments for performing a detailed chemistry, physical, and spectral analyses.”

Video credit: ESA

NASA dixit:

“June 28, 2009. As Saturn’s equinox continues to approach, the moon Pan casts a slightly longer shadow on the A ring. The novel illumination geometry created as Saturn approaches its August 2009 equinox allows moons orbiting in or near the plane of Saturn’s equatorial rings to cast shadows onto the rings. These scenes are possible only during the few months before and after Saturn’s equinox, which occurs only once in about 15 Earth years. Three stars are visible through the rings. This view looks toward the unilluminated side of the rings from about 51 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 1.4 million kilometers (870,000 miles) from Pan and at a Sun-Pan-spacecraft, or phase, angle of 80 degrees. Image scale is 8 kilometers (5 miles) per pixel.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

NASA dixit:

“June 21, 2006. The slim crescent of the moon Rhea glides silently onto the featureless, golden face of Saturn in this mesmerizing color image. In an interplay of contrast and shadow, the moon goes dark against the planet, and then its crescent suddenly brightens as it slips in front of Saturn’s night side. This view looks down onto the unlit side of Saturn’s rings, which cast soft, linear shadows onto the planet’s northern hemisphere. The images were acquired by the Cassini spacecraft wide-angle camera on March 21, 2006, at a distance of approximately 221,000 kilometers (137,000 miles) from Rhea. The image scale is approximately 13 kilometers (8 miles) per pixel.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

NASA dixit:

“March 31, 2005. NASA’s Cassini spacecraft successfully flew by Saturn’s largest moon, Titan, at about 2,400 kilometers (1,500 miles) above the surface.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

ESA dixit:

“The JUpiter ICy moons Explorer (JUICE) is the first L-class mission within ESA’s Cosmic Vision programme. It aims at a comprehensive exploration of the Jovian system with particular emphasis on Jupiter, its environment, and Galilean moons Ganymede, Europa and Callisto by investigating them as planetary bodies and potential habitats.

Scheduled for launch in 2022, with arrival in the Jovian system in 2029, JUICE will spend three-and-a-half years examining the giant planet’s turbulent atmosphere, enormous magnetosphere, its set of tenuous dark rings and its satellites. It will study the large icy moons Ganymede, Europa and Callisto, which are thought to have oceans of liquid water beneath their icy crusts – perhaps even harbouring habitable environments. The mission will culminate in a dedicated, eight-month tour around Ganymede, the first time any moon beyond our own has been orbited by a spacecraft.

JUICE will be equipped with 10 state-of-the-art instruments, including cameras, an ice-penetrating radar, an altimeter, radio-science experiments, and sensors to monitor the magnetic fields and charged particles in the Jovian system. In order to ensure it can address these goals in the challenging Jovian environment, the spacecraft’s design has to meet stringent requirements. An important milestone was reached earlier this month, when the preliminary design of JUICE and its interfaces with the scientific instruments and the ground stations were fixed, which will now allow a prototype spacecraft to be built for rigorous testing. The review also confirmed that the 5.3 tonne spacecraft will be compatible with its Ariane 5 launcher.

Operating in the outer Solar System, far from the Sun, means that JUICE needs a large solar array: two wings of five panels each are foreseen, which will cover a total surface area of nearly 100 m², capable of providing 820 W at Jupiter by the end of the mission. After launch, JUICE will make five gravity-assist flybys in total: one each at Mars and Venus, and three at Earth, to set it on course for Jupiter. Its solar panels will have to cope with a range of temperatures such that when it is flying closer to the Sun during the Venus flyby, the solar wings will be tilted to avoid excessive temperatures damaging the solar cells.

The spacecraft’s main engine will be used to enter orbit around the giant planet, and later around Jupiter’s largest moon, Ganymede. As such, the engine design has also been critically reviewed at this stage. Special measures will allow JUICE to cope with the extremely harsh radiation that it must endure for several years around Jupiter. This means careful selection of components and materials, as well as radiation shielding. One particularly important topic is JUICE’s electromagnetic ‘cleanliness’. Because a key goal is to monitor the magnetic fields and charged particles at Jupiter, it is imperative that any electromagnetic fields generated by the spacecraft itself do not interfere with the sensitive scientific measurements. This will be achieved by the careful design of the solar array electrical architecture, the power distribution unit, and the reaction wheels – a type of flywheel that stabilizes the attitude.

[…]JUICE will meet strict planetary protection guidelines, because it is imperative to minimize the risk that the potentially habitable ocean moons, particularly Europa, might be contaminated by viruses, bacteria or spores carried by the spacecraft from Earth. Therefore, mission plans ensure that JUICE will not crash into Europa, on a timescale of hundreds of years.”

Video credit: ESA