“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.”
“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.”
“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.”
“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.”
“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.”
“The AIM spacecraft will be launched in October 2020 on board a Soyuz-Fregat launch vehicle from Kourou. After launch and one or more deep-space manoeuvres, AIM will arrive at Didymos in June 2022, some months before DART’s impact.After arrival, the AIM spacecraft will transition into a heliocentric co-flying orbit, from which it will observe the binary system to derive a high-resolution 3D model of the asteroid, determine its mass and dynamical state, and characterise its surface and shallow sub-surface properties by means of a thermal infrared imager and high-frequency radar. This first characterisation phase would last for a couple of months and be conducted from a distance of between 35 to 10 km from the asteroid. Following this, the AIM spacecraft will release a number of CubeSats and a lander which is based on DLR’s MASCOT lander used for the JAXA Hayabusa-2 mission. The lander will carry out a detailed characterization of the deep-interior structure of the asteroid by means of a low-frequency bistatic radar. Approximately two weeks before DART impact, the AIM spacecraft would be moved to an orbit about 100 km from the asteroid to safely conduct impact observations. After the impact, a second characterisation phase would conclude the mission.
The AIM spacecraft is based on a very simple design with fixed solar arrays and a fixed high-gain antenna. The baseline propulsion system uses a bi-propellant (MMH/MON) fuel with 24 thrusters each capable of producing 10 N of thrust. A separate Helium tank would keep the four 60 l propellant tanks pressurized. Power is generated by two deployable, fixed solar arrays with an output of 165 W each at a distance of 2.2 AU from the Sun, and a total panel surface of 5.6 m². The total spacecraft dry mass would be about 420 kg and the propellant mass about 292 kg.
The target of the AIM mission is asteroid 65803 Didymos (1996 GT), an Apollo-type near-Earth orbit (NEO) with a perihelion that is just below the aphelion radius of Earth orbit. Didymos is a binary body; the primary body has a diameter of around 750 m and a rotation period of 2.3 hours, while the secondary body had a diameter of around 170 m and rotates around the primary at a distance of 1.2 km in 12 hours. Study of the Didymos moon should offer valuable insights into the origins of our Solar System, and help scientists develop planetary defence strategies against any incoming asteroids in the future. Informally called ‘Didymoon’, the asteroid is nearly three times larger than the body thought to have caused the 1908 Tunguska impact in Siberia, the largest impact in recorded history. An equivalent asteroid striking Earth would be well into the ‘city-killer’ class, leaving a crater of at least 2.5 km diameter and causing serious regional and climate damage. The 2013 Chelyabinsk airburst, whose shockwave struck six cities across Russia, is thought to have been caused by an asteroid just 20 m in diameter.”
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