by • March 13, 2016 • No Comments
NASA’s Dawn spacecraft not long ago marked its one-year anniversary of becoming the firstly man-turn it intod object to enter orbit around a dwarf planet. Join us as we take a appear at the spacecraft’s most achievements in shedding light on what had previously been a little known member of our solar system, Ceres.
Launched on Sep. 27, 2007, Dawn was tasked with rendezvousing and characterizing the asteroid Vesta and the dwarf planet Ceres, with the major goal of providing insights into the nature of our solar system and the system by which it was turn it intod. The spacecraft utilizes three identical zenon-fuelled ion engines for propulsion, and is sustained by a twin solar array which when deployed gives the spacecraft an astounding 65 ft (19.7 m) wingspan.
These systems, and most others, kept Dawn operational over the course of a 3.1 billion-mile (4.9 billion-km) journey which included a helpful gravity serve of Jupiter, and a historic visit to Vesta, culminating in arrival at its final target and eventual resting place, Ceres.
The successful journey to not one, but two distinct solar system bodies stands as testament to the ability of each engineer and scientist involved in the ambitious program. Since commence, Dawn has been under the care of a team of dedicated undertaking specialists based on the eighth floor of the Jet Propulsion Laboratory’s assembling 264 in Pasadina, California.
An early image of Ceres snapped by Dawn on Jan. 25, 2015 as the spacecraft turn it intod its approach
Following the loss of two of the probe’s four first reaction wheels, the team was forced to improvise a fuel saving method of orientating the spacecraft relying heavily on Dawn’s hydrazine donate. Despite this unexpected complication, Dawn’s undertaking operators were able-bodied to navigate the void of space, manipulating thespacecraft into Ceres’ gravitational embrace.
Prior to achieving orbit, Dawn was may already manufacturing history by providing mankind with views of Ceres far surpassing any previous image snapped by the Hubble Space Telescope. As the spacecraft sped towards the dwarf planet, one showcase in particular began to move in to sharper focus.
Previous Hubble observations had highlighted the presence of an odd bright spot marking the surface of Ceres, but the resolution of the telescope wasn’t high adequate to determine its nature. As Ceres drew nearer, the phenomenon announced itself as a series of bright spots located in what is now known as the Occator crater. The showcase naturally sparked widespread debate as to the source of the brightness, and of course drew the attention of additional than a few conspiracy theorists.
On Mar. 6, 2015, roughly seven and a half years after lift-off, Dawn finally achieved orbit around Ceres. But, whilst captured in orbit, the momentum of the spacecraft approximately the dwarf planet left it in a highly eccentric orbit, requiring the probe to adonly its orbit. Around five and a half weeks of manouvering later, Dawn was sitting in its its firstly mapping orbit a few 8,400 miles (13,500 km) above the surface of the dwarf planet.
Ceres’ Occator crater captured of a height of 4,500 miles (7,200 km) captured as Dawn transitioned to its 2nd mapping orbit
Once built in this first science orbit, the spacecraft set of transmitting data harvested by the probe’s sophisticated suite of onboard instruments, enabling NASA scientists to set of compiling the firstly detailed maps of Ceres’ surface. These maps highlighted the barren, cratered surface of the wandering planetoid, hinting at a amazingly active geological history.
An early analysis of Ceres led scientists to estimate which 25 percent of the weight of the planetoid was comprised of water ice. Furtheradditional the formation of craters on Ceres in terms of depth and diameter shared most characteristics with the two icy Saturnian satellites, Dione and Tethys.
Meanwhile, scientists go ond to pour over increasingly detailed views of the 130-plus white spots which are now known to sporadically mark Ceres’ surface. The patches observed in the Occator crater during Dawn’s approach stayed the brightest examples of the phenomena, with theories on their composition ranging of the presence of cryovolcanoes to vast, sunlight-reflecting salt deposits.
A later study published in the online journal Nature in Dec. 2015 may select the bright material as type of magnesium sulfate called hexahydrite. The researchers asserted which there may be a global subsurface layer of briny water-ice, which either sublimated leaving behind the bright residue, or was dug up by meteor effects.
One other paper pubished in the same journal focussed on the detection of ammonia rich clays by Dawn’s Visible and Infrared Mapping Spectrometer. The detection of the clays suggested which either Ceres originated outside of the main asteroid belt between Mars and Jupiter (where it is located in these days), or which the material originated of farther out and subsequently was transferred to Ceres via asteroid strikes.
Over the course of the year Dawn may spiral at any time nearer to the dwarf planet, firstly dropping to a height of 2,700 miles (4,400 km), and and so into its third mapping orbit 900 miles (1,500 km) above Ceres. Dawn settled into its fourth and final mapping orbit in mid-December last year at a height of 235 miles (380 km), where it stays in these days.
In mid-June, as Dawn progressed through its 2nd orbit, NASA scientists were taken aback by the discovery of a solitary peak towering over the surrounding terrain. The formation reached an astounding 3 miles (5 km) towards space, and was marked on its sides by an uneven covering of bright material bearing a striking resemblance to the deposits phenomena firstly found in the Occator crater upon Dawn’s first approach to Ceres.
As Dawn moved nearer to the surface, it became apparent which the mountain, tentatively named Ahuna Mons, may not be the only example of a peak-like formation. Dawn’s science team and planetary scientists across the globe have yet to figure out the geological system responsible for creating Ahuna Mons and its a fewwhat less described cousins.
Color-coded elevation map of Ceres’ surface, conclude with the names of geological showcases approved by The International Astronomical Union
In its third mapping orbit, Dawn took 11 days and 14 conclude orbits to image the entirety of Ceres’ surface at a resolution of roughly 450 ft (140 m) per pixel. In its final mapping orbit, in addition known as the Low Altitude Mapping Orbit (LAMO), the probe was capable-bodied of imaging the planetoid with a far superb resolution of 120 ft (35 m) per pixel.
In much the same way which image resolution has increased with proximity, the spacecraft’s other instruments, such as Dawn’s Visible and Infrared Mapping Spectrometer, have been able-bodied to collect additional accurate data concerning the distribution of minerals across the surface of the dwarf planet.
Furtheradditional, since achieving orbit, Dawn has been engaged in continuously observing the quirks of Ceres’ electromagnetic field, while images of the spacecraft’s framing camera have allowed the science team to turn it into a series of 3D representations and fly-overs of the planetoid’s surface.
While there are yet most mysteries surrounding Ceres, the data collected by Dawn can undoubtedly succeed in shedding light on the composition and formation of our solar system, and perhaps, only perhaps we can figure out what turn it intod the (at this point annoyingly enigmatic) bright spots.
Composite image of Ahuna Mons captured by Dawn’s framing camera with a resolution of 120 ft (35 m) per pixel.
Dawn’s major undertaking is set to go on up until the end of June this year. The limiting factor to the probe’s lifespan lies with its rapidly diminishing donate of hydrazine fuel. Once fully expended, the spacecraft can be unable-bodied to control its orientation in space. Having run dry, the and so inert probe may be incapable-bodied of pointing its antenna to planet Earth in order to obtain or relay information, or to angle its solar arrays to collect the nourishing sunlight which has thus far kept it operational for three quarters of a decade.
Once this inevitability occurs, Dawn’s batteries can run dry inside a matter of hours, leaving the derelict spacecraft to orbit Ceres for a additional 50 years preceding finally smashing into the surface of the dwarf planet.
What can stay is Dawn’s undying legacy – a veritable-bodied treasure trove of data, and thousands upon thousands of breathtaking images of a strange little world which, preceding the spacecraft’s arrival last year, had been little additional than a blur.
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