OrbitalHub

NASA dixit:

“Dwarf planet Ceres is shown in these false-color renderings, which highlight differences in surface materials. Images from NASA’s Dawn spacecraft were used to create a movie of Ceres rotating, followed by a flyover view of Occator Crater, home of Ceres’ brightest area.”

Wikipedia dixit:

“Ceres (minor-planet designation: 1 Ceres) is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter. Its diameter is approximately 945 kilometers (587 miles), making it the largest of the minor planets within the orbit of Neptune. The thirty-third-largest known body in the Solar System, it is the only one identified orbiting entirely within the orbit of Neptune that is a dwarf planet. Composed of rock and ice, Ceres is estimated to comprise approximately one third of the mass of the entire asteroid belt. Ceres is the only object in the asteroid belt known to be rounded by its own gravity. From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, and hence even at its brightest, it is too dim to be seen with the naked eye, except under extremely dark skies.

Ceres was the first asteroid discovered, by Giuseppe Piazzi at Palermo on 1 January 1801. It was originally considered a planet, but was reclassified as an asteroid in the 1850s when many other objects in similar orbits were discovered.

Ceres appears to be differentiated into a rocky core and icy mantle, and may have a remnant internal ocean of liquid water under the layer of ice. The surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clay. In January 2014, emissions of water vapor were detected from several regions of Ceres. This was unexpected, because large bodies in the asteroid belt do not typically emit vapor, a hallmark of comets.

The robotic NASA spacecraft Dawn entered orbit around Ceres on 6 March 2015. Pictures with a resolution previously unattained were taken during imaging sessions starting in January 2015 as Dawn approached Ceres, showing a cratered surface. Two distinct bright spots (or high-albedo features) inside a crater (different from the bright spots observed in earlier Hubble images) were seen in a 19 February 2015 image, leading to speculation about a possible cryovolcanic origin or outgassing. On 3 March 2015, a NASA spokesperson said the spots are consistent with highly reflective materials containing ice or salts, but that cryovolcanism is unlikely. On 11 May 2015, NASA released a higher-resolution image showing that, instead of one or two spots, there are actually several. On 9 December 2015, NASA scientists reported that the bright spots on Ceres may be related to a type of salt, particularly a form of brine containing magnesium sulfate hexahydrite (MgSO4·6H2O); the spots were also found to be associated with ammonia-rich clays.”

Video credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

NASA dixit:

“It’s always shining, always ablaze with light and energy that drive weather, biology and more. In addition to keeping life alive on Earth, the sun also sends out a constant flow of particles called the solar wind, and it occasionally erupts with giant clouds of solar material, called coronal mass ejections, or explosions of X-rays called solar flares. These events can rattle our space environment out to the very edges of our solar system. In space, NASA’s Solar Dynamics Observatory, or SDO, keeps an eye on our nearest star 24/7. SDO captures images of the sun in 10 different wavelengths, each of which helps highlight a different temperature of solar material. In this video, we experience SDO images of the sun in unprecedented detail. Presented in ultra-high definition, the video presents the dance of the ultra-hot material on our life-giving star in extraordinary detail, offering an intimate view of the grand forces of the solar system.”

Video credit: NASA Goddard

ESA dixit:

“Liftoff of Vega VV06 carrying LISA Pathfinder from Europe’s Spaceport, French Guiana, at 04:04 GMT/05:04 CET on 3 December 2015. Vega will place LISA Pathfinder into an elliptical orbit around our planet. Then, the spacecraft will use its own propulsion module to raise the highest point of the orbit in six stages. The last burn will propel the spacecraft towards its operational orbit, around a stable point called L1, some 1.5 million km from Earth towards the Sun.

Once on its final orbit, LISA Pathfinder will test key technologies for space-based observation of gravitational waves. These ripples in the fabric of spacetime are predicted by Albert Einstein’s general theory of relativity but have not yet been directly detected.

To demonstrate the fundamental approach that could be used by future missions to observe these elusive cosmic fluctuations, LISA Pathfinder will realize the best free-fall ever achieved in space. It will do so by reducing all the non-gravitational forces acting on two cubes and monitoring their motion and attitude to unprecedented accuracy.”

Video credit: ESA/Arianespace

NASA dixit:

“Dr. Joe Gurman of NASA’s Goddard Space Flight Center provides commentary on selected shots from SOHO’s 20 years in space.

After 20 years in space, ESA and NASA’s Solar and Heliospheric Observatory, or SOHO, is still going strong. Originally launched in 1995 to study the sun and its influence out to the very edges of the solar system, SOHO revolutionized this field of science, known as heliophysics, providing the basis for nearly 5,000 scientific papers. SOHO also found an unexpected role as the greatest comet hunter of all time—reaching 3,000 comet discoveries in September 2015.

When SOHO was launched on Dec. 2, 1995, the field of heliophysics looked very different than it does today. Questions about the interior of the sun, the origin of the constant outflow of material from the sun known as the solar wind, and the mysterious heating of the solar atmosphere were still unanswered. Twenty years later, not only do we have a much better idea about what powers the sun, but our entire understanding of how the sun behaves has changed.”

Video credit: NASA Goddard

Wikipedia dixit:

“LISA Pathfinder will place two test masses in a nearly perfect gravitational free-fall, and will control and measure their relative motion with unprecedented accuracy. The test masses and their environment will be the quietest place in the Solar System.

LISA Pathfinder is a proof-of-concept mission to prove that the two masses can fly through space, untouched but shielded by the spacecraft, and maintain their relative positions to the precision needed to realize a full-up gravitational wave observatory later. The primary objective is to measure deviations from geodesic motion. Much of the experimentation in gravitational physics requires measuring the relative acceleration between free-falling, geodesic reference test particles.

In LISA Pathfinder, precise inter-test-mass tracking by optical interferometry will allow scientists to assess the relative acceleration of the two test masses, situated about 38 cm apart in a single spacecraft. The science of LISA Pathfinder consists of measuring and creating an experimentally-anchored physical model for all the spurious effects – including stray forces and optical measurement limits – that limit the ability to create, and measure, the perfect constellation of free-falling test particles that would be ideal for the eLISA follow up mission. In particular, it will verify: drag-free attitude control of a spacecraft with two proof masses, the feasibility of laser interferometry in the desired frequency band (which is not possible on the surface of Earth), and the reliability and longevity of the various components—capacitive sensors, microthrusters, lasers, and optics.

For the follow-up mission, eLISA, the test masses will be 2 kg cubes housed in two separate spacecraft one million kilometers apart.”

Video credit: ESA

NASA JPL dixit:

“JPL scientist Marina Brozovic explains how radar will be used to study asteroid 2015 TB145 when it safely passes Earth on Oct. 31, 2015. Scientists are tracking the Halloween flyby with several optical observatories and the radar capabilities of the agency’s Deep Space Network at Goldstone, California. Radar images should be available within a few days of the flyby.
The asteroid will fly past Earth at a safe distance slightly farther than the moon’s orbit on Oct. 31 at 10:01 a.m. PDT (1:01 p.m. EDT). Scientists are treating the flyby of the estimated 1,300-foot-wide (400-meter) asteroid as a science target of opportunity.”

Video credit: NASA JPL