Dawn (from English - "Breaking Dawn", pronounced Don ) - automatic interplanetary station (AMC), launched by NASA on September 27, 2007for the study of the asteroid Vesta and the dwarf planet Ceres .
Dawn | |
---|---|
AMC Dawn in interplanetary flight (computer graphics) | |
Customer | NASA |
Manufacturer | Orbital Sciences Corporation |
Operator | Jet Propulsion Laboratory , University of California, Los Angeles |
Tasks | study of Vesta and Ceres |
Span | Mars |
Launch pad | SLC-17 , US Air Force Base at Cape Canaveral , Florida |
Carrier rocket | Delta-2 7925H |
Launch | September 27, 2007 11:34:00 UTC |
Going into orbit | July 16, 2011 - Vesta [1] [2] , March 6, 2015 - Ceres [3] [2] |
Flight duration | in flight 11 years, 9 months, 23 days |
Descent from orbit | September 5, 2012 - Vesta [2] [4] |
NSSDC ID | 2007-043A |
SCN | 32249 |
Specifications | |
Weight | at the time of launch 747.1 kg + fuel: 425 kg - xenon , 45.6 kg - hydrazine [2] |
Dimensions | 1.64 x 1.27 x 1.77 m. + Solar panels - 8.3 x 2.3 m., Antenna diameter - 1.57 m. [2] |
Power | 10.3 kW at the time of launch in 1 AU from the Sun, 1.3 kW in 3 AU from the sun [5] |
Power sources | 2 solar panels [5] [2] |
Orientation | reactive control system + [5] |
Active life | 10 years |
Target equipment | |
Transmission speed | 7.8 bps - 2.0 kb / s - sending data, 10 bps - 124 kb / s - receiving data [5] |
Mission logo | |
Project site | |
“Dawn” was the first mission to research from the orbit of more than one celestial body, the first apparatus to work in the orbit of the main belt asteroid (from 2011 to 2012) and the first in the orbit of the dwarf planet (from 2015 to the present) [2] .
Overall project management is provided by the Jet Propulsion Laboratory . The contract for the development and manufacture of the device was concluded with Orbital Sciences Corporation ( Dallas , VA , USA), where project manager Michael Mook was responsible for it. The research program of the mission is the responsibility of the University of California at Los Angeles (project supervisor ), whose partners are the Los Alamos National Laboratory , ( Katlenburg-Lindau , Germany), Institute of Planetary Research of the German Center for Aviation and Aerospace (DLR) ( Berlin ), Institute of Computer and Communication Engineering, Braunschweig Technical University , ( Rome ) and the Italian Space Agency ; the launch vehicle was supplied by the United Launch Alliance ( Denver , Colorado ) [6] [5] .
The cost of the mission is $ 373 million for the construction and launch of the device, then by 2015 - $ 99 million for the subsequent support - work and data analysis [2] .
Aims and Objectives
The name AMC is English. Dawn, Zarya is not associated with any particular person, but is a simple way of describing the main goal - obtaining information that will help to better study the early stages of the formation of the Solar System [7] . Vesta and Ceres are the most massive asteroids [8] , which almost completely survived the entire evolution of the Solar system and therefore retained evidence of the physico-chemical conditions “at the dawn” of the formation of our planetary system. At the same time, Vesta and Ceres, although they were formed and evolved so closely from each other, are opposite types of large asteroids: Vesta is anhydrous achondrite , which in the early stages underwent differentiation and melting of the core and the main part of the mantle , while Ceres contains a huge amount of ice, significantly slowed down thermal processes in it. Thus, the Dawn mission to study these asteroids links the study of the stone bodies of the inner solar system and the ice in the outer part [5] . It consists in achieving the following goals [2] [5] :
- Investigate the internal structure, density (determine the bulk density with an accuracy of at least 1%) and the homogeneity of the two protoplanets
- Determine surface relief and cratering
- Determine the mass distribution, build a gravitational field (with a half-wave resolution of at least 90 km and 300 km, respectively), set the location of the main axes, rotation axes (with an accuracy of at least 0.5%), obtain inertia moments for both bodies
- Establish the exact shape, size, composition and mass of Vesta and Ceres
- To study the role of water in the process of evolution of asteroids
- Check out the theory that Vesta is the source of stone meteorites like ( , and diogenites ), and describe them from a geological point of view, as well as determine which meteorites originate from Ceres.
For this, the following tasks must be performed [2] [5] :
- Obtain images of at least 80% of the surface of Vesta and Ceres with a resolution of no worse than 100 m / pixel and 200 m / pixel, respectively, with a signal / noise ratio of at least 50 without a filter and at least 3 color filters
- Make a mapping of the surface using a spectrometer in the wavelength range with a length of 0.4-5.0 microns
- Topographicize at least 80% of Vesta's surface with a horizontal resolution of no worse than 100 m and vertical - no worse than 10 m, and Ceres - with a horizontal resolution no worse than 200 m and vertical - no worse than 20 m
- To carry out radio sounding to determine the parameters characterizing Vesta and Ceres from the point of view of the dynamics of a solid body
- Obtain neutron and gamma spectra for mapping the chemical composition of surface relief components, including the distribution of the contents of the main rock-forming elements ( oxygen , magnesium , aluminum , silicon , calcium , titanium and iron ), trace elements ( gadolinium and samarium ) and long-lived radioactive elements ( potassium , thorium and uranium ), as well as Hydrogen in the entire surface layer (1 m thick) of both protoplanets with an accuracy of at least 20% and a resolution of about one and a half distances equal to the height of the shooting.
The design of the device
The AMS “Dawn” was made by Orbital Sciences based on the platform , created for small geostationary communications satellites [6] . The station is based on a cylinder made of graphite composite material . Inside it are tanks for fuel - xenon in the form of gas for ion engines and hydrazine for conventional ones. Outside the cylinder, aluminum panels with aluminum coating are mounted, on which most of the remaining equipment is installed. The main antenna is mounted on one side of the case, and the solar battery drives are mounted on the other two. The quick access panel and other panels are made of aluminum and have an aluminum or composite coating. The temperature of the device is controlled by thermal insulating screens, radiators on the surface of the case, its polishing coating, as well as more than 140 electric heating elements [2] [6] .
An 8 × 8 mm silicon wafer is installed onboard Dawn, bearing the names of 365,000 people on Earth who have submitted an application [6] [9] .
Ion engine
The AMC is equipped with three xenon ion engines manufactured by L-3 Communications , developed on the basis of a sample tested on a Deep Space 1 probe. They are installed in the lower part of the device: one along the axis, two more - on the front and rear panels.
The principle of operation is the acceleration in the electric field of xenon fuel ions (up to a speed almost 10 times greater than in conventional chemical engines). Each engine measuring 33 cm (length) by 30 cm (nozzle diameter) and weighing 8.9 kg has a thrust of 19–92 mN and a specific impulse of 3200–1900 s. Acceleration and braking are provided by adjusting the electric power (from 0.5 to 2.6 kW, which are supplied directly from solar panels at a voltage of from 80 to 160 V) and the fuel supply level. The movement is carried out through the work of one of the three engines. In normal operation, the Dawn Ion engines provide a speed increase of 97 km / h (60 mph) every 4 days. The regular mode of spacecraft acceleration is a weekly one with a break of several hours to “communicate” with the Earth. The total estimated duration of operation of the three engines is approximately 2000 days, including 1885 days before the arrival of Ceres in orbit [6] .
Xenon was chosen as a fuel because it is chemically inert, easily stored in a compressed form, and has a sufficiently large atomic mass to provide greater traction compared to other substances. The fuel is consumed economically - 3.25 mg per second (or about 10 ounces (280 g) per day) at the maximum intensity of work. At the time of launch, xenon in gaseous form was stored in the fuel tank at a density of 1.5 times the greater density of water. Out of 425 kg of the working body (xenon) available on board, it was supposed to spend 275 kg on the Earth-Vesta flight, 110 kg on the West-Ceres flight [2] [5] .
Research Tools
Name | Appearance | Purpose | Description | Developer |
---|---|---|---|---|
Frame Camera ( Eng. Framing camera (FC) ) | Obtaining detailed optical images, as well as navigation when approaching targets | Two (separately placed) cameras are installed on the probe, each with its own set of optics and electronics, and one of them is used during the shooting - the main one or the reserve one. Each camera is equipped with a black and white CCD sensor (1024 × 1024 pixels ), a lens with a diameter of 19 mm, a relative aperture of f / 7.9 and a focal length of 150 mm, a set of 7 narrowband (6 with a half width of 40 nm and 1 with a half width of 80 nm; the widest - from 450 to 920 nm) color filters + empty field; has a field of view of 5.5 × 5.5 degrees; holding time can be set from 0.001 s to 3.5 hours. In addition to visible light, cameras are capable of detecting waves in the near infrared range. They also have their own digitization system and an 8 GB internal memory. | The cameras were created by with the participation of the Institute of Planetary Studies of the German Aviation and Cosmonautics Center (DLR) and the Institute of Computer Engineering and Communication Networks of the Technical University of Braunschweig ; is run by the German Center for Aviation and Cosmonautics (DLR) and the Max Planck Society Institute for Solar System Research [2] [10] [11] [5] | |
Detector of neutrons and gamma-quanta ( eng. Gamma Ray and NeutronDetector (GRaND) ) | Determination of the chemical composition of the surface layer of Vesta and Ceres to a depth of 1 m. | The design is based on a gamma-spectrometer and a neutron spectrometer onboard an AMS Lunar Prospector , also launched as part of the Discovery program, and a gamma-ray spectrometer installed on a Mars Odyssey apparatus. The device is equipped with 21 sensors (in 4 main channels) for recording the energies of gamma rays and neutrons reflected from the surface of the test body or emitted by it, and this signal is separated from the background. A photomultiplier detects scintillations caused by the interaction of gamma rays with a crystal, as well as the creation of free charge carriers in a semiconducting crystal. Peripheral and fast neutrons are detected by their interaction with scintillators of borated plastic; the gamma rays formed there are recorded by BGO and CdZnTe crystals. The scintillators are optically coupled to photomultipliers to enable registration of low-energy photons. The same photomultipliers associated with lithiated glass scintillators serve to register thermal neutrons . GRaND has a very wide field of view , but the sensitivity is not the same everywhere, the half-width of the minimum soluble surface area is about one and a half distances equal to the height of the shooting. However, knowing the location of geological objects, determined by other devices, it is possible to obtain the spatial distribution of chemical elements with a resolution that is 3 times better than the intrinsic resolution of the neutron detector and gamma quanta [5] . Unlike other tools, the detector does not have its own internal storage device. | The instrument is manufactured by the Los Alamos National Laboratory , and the working group at the US Planetological Institute is responsible for it [2] . | |
Visible and Infrared Mapping Spectrometer (VIR) spectrometer | Mineralogical analysis of the surface of Vesta and Ceres | The device is a modification of spectrometers used on the Rosette and Venus Express space probes , and also inherited a number of structural elements from a similar instrument on board the Cassini apparatus. The instrument registers the intensity of illumination of each pixel of the CCD array for wavelengths of 0.25–1 μm, or an array of photodiodes HgCdTe at a temperature of 70 K for wavelengths of 0.95–5 μm — a total of 400 different wavelengths in the visible and infrared ranges — then from comparing the resulting picture with known laboratory data can draw conclusions about the mineralogical composition of the surface of Vesta and Ceres. The spectrometer has a slit length of 64 mrad, the amount of internal memory is 6 GB, which can be used as 2 GB of data backup. | The device was created by , a subsidiary of the Leonardo holding company, funded by the Italian Space Agency under the supervision of the , which is responsible for his work [2] [5] [6] . |
In addition to special tools, the radio complex apparatus should be used to study the gravitational field of Vesta and Ceres. Taking signals from the probe using antennas on Earth (constantly tracking the speed of spacecraft and recording radio eclipses), small variations in the gravitational field can be observed, giving information about the mass distribution inside the studied bodies, based on which one can, in turn, draw conclusions about their internal structure [6] . The NASA Jet Propulsion Laboratory [2] [5] is responsible for the gravitational experiment.
Solar Panels
The electric power plant provides with power supply all the systems onboard the apparatus, including the ion engine during periods of its active work, as well as the thermal control system. Each of the two 5-section solar cells measuring 8.3 by 2.3 m and weighing 63 kg is covered with 5,740 InGaP / InGaAs / Ge photocells, which convert about 28% of the solar radiation incident on them into electricity. On Earth, they together would generate more than 10 kW, and at a distance of 3 a. e. from the Sun the maximum power is 1.3 kW. The panels are installed on opposite sides of the probe with the help of the Cardan suspension of the system, which allows them to be oriented perpendicular to the solar flow. A 35 amp-hour nickel-hydrogen battery and a charging electronics kit provide continuous power even when the panels do not catch solar radiation [2] [5] [6] .
Orientation and Stabilization System
In the usual mode of movement , the orientation system determines the station position using 2 star sensors and 16 solar coarse sensors, in separate operation modes 3 gyros are additionally used. The orientation of the device, especially solar panels on the Sun, can be carried out using a reactive control system and 4 , and both methods can be used in combination with an ion engine in the mode of its active work. The reactive control system consists of 12 micro- LREs MR-103G with 0.9 N hydrazine fuel and can be used both for direct orientation control and for unloading flywheels. The same system is responsible for tracking the sun with the sun and for turning the ion engines in the gimbal suspension (so that as the tanks empty out, the thrust vector passes through the center of mass of the spacecraft) [6] . In addition, a certain amount of hydrazine is provided for maneuvers to adjust the orbit, if in the thrust mode of an ion engine it is necessary to quickly gain the necessary change in speed [5] .
Data Management System
The on-board data management system is based on the RAD6000 processor, the C software is used under the control of the VxWorks OS . The control module also includes 8 GB of memory for storing engineering and scientific data. The system receives telemetry data from all sensors of the orientation system and sends commands to its drives thanks to the installed drivers for them [5] .
The onboard cable network of the spacecraft consists of approximately 9000 wires with a total length of about 25 km, with the weight of cables together with connectors reaching 83 kg [6] .
Communication
Telecommunication with the Earth is made in the X-band using a , also successfully proven to work on the Deep Space 1 probe and used on most NASA missions beyond the orbit of the Moon, beginning with Mars Odyssey . 100-watt amplifiers on a traveling-wave tube are similar to those installed on a Mars Reconnaissance Orbiter . Data transmission is mainly carried out using a parabolic antenna with a high gain with a diameter of 1.52 m, or, when it is not directed towards the Earth, one of the three antennas with a low gain. The transfer speed is from 10 bps to 124 kb / s, receiving (from the earth) from 7.8 bps to 2 kb / s [2] [5] .
Flight plan
The flight plan, designed for 8 years, provides for a diverging spiral trajectory describing three revolutions around the sun .
- September - October 2007 - starting from the Earth.
- February 2009 - a maneuver in the gravitational field of Mars with a set of speed.
- August 2011 - Arrival in the area of Vesta and the transition with the help of xenon ion engines into the orbit of the asteroid satellite.
- August 2011 - August 2012 - the study of the asteroid Vesta.
- August 2012 - departure along the unwinding spiral from the gravitational field of Vesta and transfer to the flight orbit to Ceres.
- March 2015 - arrival to Ceres and the transition to its orbit.
- July 2016 - completion of the main mission [12] .
According to the original plan [5], the device should have been in orbit around Vesta until May 2012, but this period was extended until August, with the aim of more fully mapping some areas that remained in the shadows. This did not affect the time of arrival to Ceres.
On July 1, 2016, the leadership of NASA decided to leave the probe in orbit at Ceres, although the leadership of the Dawn mission suggested using the remaining fuel from the spacecraft to fly to the asteroid (145) Adeona [13] [14] . On October 19, 2017, the expanded mission was again extended until the second half of 2018, when the fuel resource was exhausted [15] .
Mission History
AMS “Dawn”, the ninth mission of the , was accepted by NASA in November 2002 [16] .
The mission was at least three times frozen or completely canceled (2003, 2005, 2006). However, after the last public statement on the refusal of the flight to Ceres in March 2006, this decision was officially canceled, and on March 27, 2006, Dawn received a go-ahead for launch. In September 2006, AMC was already in a state of readiness for launch. On April 10, 2007, the satellite was delivered to the installation workshop of the launching contractor, SPACEHAB, Inc in Florida . The launch was originally scheduled for June 20, but then it was postponed until June 30 and July 7 due to the missile’s unavailability, and then until July 15 due to problems with aircraft and sea measurement points to accompany the launch; it could be completed before July 19, since only before this date there were conditions for a meeting with Mars. However, on July 7, it was announced that the launch was postponed to autumn, to the next astronomical window - in order to avoid the overlap in time of the launch and the first phases of the flight of Dawn and AMC Phoenix (which took place on August 4, 2007). Because of the Phoenix apparatus, it was necessary to partially disassemble the rocket to launch Dawn in order to minimize the risk of possible problems with the Phoenix launcher in the immediate vicinity.
Finally, on September 11, 2007, the 3rd stage of the AMC launch vehicle on it was again delivered to the launch complex 17-V at the launch site at Cape Canaveral . The launch of the device was carried out on September 27, 2007 [17] . After almost three months of testing the on-board systems in Earth orbit [18] , on December 17, 2007, Dawn went to Mars [6] [19] , the orbit of which the device reached on February 17 [20] [21] . Having completed the gravitational maneuver around the planet [21] , the device rushed to the asteroid belt.
Learning Vesta
On May 3, 2011, the probe made the first photograph of Vesta from a distance of about 1.21 million km [22] [23] , and the stage of active study of the asteroid began [24] . During May, a series of navigation pictures of the asteroid were taken from a distance of about 640 thousand - 1 million km. [25] .
By June 27, the device reduces speed, getting closer to Vesta [26] [27] [28] . On July 16, having made almost two rotations around the Sun , Dawn reached Vesta and moved to its circular orbit with an altitude of 16,000 km. [1] [28] [29] . All July, the device was engaged in shooting the surface of Vesta [30] .
On August 11, the main stage of research and information gathering ( Survey ) began with the help of all three instruments from an orbit of 2,700 km in height, to which Dawn successfully passed on August 2 [31] [32] [33] [34] . By August 31, more than 2,800 images and more than 3 million spectra in the visible and IR ranges were obtained, which far exceeded the plan [35] [34] .
On September 18, the device went down even lower - to an orbit of 680 km - “High Cartographic Orbit”, High altitude mapping orbit , abbr. HAMO [36] [37] . On September 29, the second stage of work (the most intensive) began in HAMO orbit for 30 days, during which about 60 revolutions should be completed - 6 shooting cycles at different angles of 10 revolutions, during which detailed surface mapping was performed to study geological processes on the asteroid, as well as the study of its gravitational field [38] [39] [37] . The Dawn camera took more than 7,000 photographs that formed the basis of Vesta’s photo archive in terms of coverage and detail; VIR-spectrometer shot more than 15,000 frames, which allowed to build a detailed geological map of the asteroid; The GRaND detector also began collecting data.
On December 8, the device switched to “Low Cartographic Orbit”, Low altitude mapping orbit , abbr. LAMO [34] altitude of 210 km. [40] [41]
- December 12 - Launch of LAMO in orbit for at least 10 weeks [42] . The main objectives of this stage of the flight were precise measurements of the gravitational field to determine the mass distribution in the depths of the asteroid; registration by the GRaND detector of the neutron spectrum and gamma quanta generated by the interaction of cosmic rays with the surface of Vesta, to determine the elemental composition of matter on the surface of the asteroid [43] [44] . On December 13, the probe sent the first photos of Vesta to Earth with the highest possible resolution (up to 23 megapixels , which is 3 times better than in the previous orbit). It took more than a week to process the data. All collected photos are used to create a high resolution map of Vesta [45] [46] .
Dawn's main research program was completed, it was extended on April 18th until August 26th. The probe remained in a low orbit to collect additional data on the composition of the surface and the gravitational field, then move to a higher (680 km) for a more detailed study of the northern hemisphere, not previously illuminated by the Sun. On June 5, the device completed the transition to an orbit of 680 km with a 12-hour circulation period [47] . Having completed the expanded program (a total of 31 thousand photos were obtained with a conventional camera and 20 million spectra in the visible and IR ranges), on September 5, 2012, the device left the Vesta orbit and headed for the next object of research - Ceres [48] [4] [49 ] , the transition to which took two and a half years.
On January 13, from a distance of 383 thousand km, an image of Ceres 27 pixels in size was obtained. Elements of the surface structure, such as craters, are distinguishable in the photographs [50] . From this moment begins the taking of pictures of the approaching Ceres [51] [52] [53] [54] [53] [55] [53] [56] [53] .
[57] .
Exploring Ceres
Code name | Working hours | Height above the surface, km | Period of treatment | Shooting resolution, m / pix |
---|---|---|---|---|
RC3 | 04/23/15 - 05/09/15 | 13,600 | 15 days | 1,300 |
Survey | 06.06.15 - 06.30.15 | 4,400 | 3.1 days | 410 |
HAMO | 08/17/15 - 10/23/15 | 1,470 | 19 hours | 140 |
LAMO / XMO1 | 12/16/15 - 09/02/16 | 385 | 5.4 hours | 35 |
Xmo2 | 16.10.16 - 04.11.16 | 1,480 | 19 hours | 140 |
XMO3 [59] [60] | 12/05/16 - 02/22/17 | 7 520 - 9 350 | ~ 8 days | ~ 700 [61] |
XMO4 [62] | 04/17/17 - | 13,830 [63] - 52,800 [64] | 59 days [62] |
March 6, 2015, having overcome a total of 4.9 billion km, the device was captured by the gravitational field of the dwarf planet at a distance of 60,600 km from it [65] [3] [66] [57] .
On April 23, “Dawn” successfully switched to a circular scientific orbit RC3 of 13.6 thousand kilometers, new pictures of the dwarf planet were made [67] [68] [69] [70]
On June 6 and 9, the first photographs from the second scientific orbit (4,400 km) were obtained. The bright areas inside the crater with a diameter of 90 km still cause the greatest interest - a large spot with a diameter of about 9 km and at least 8 smaller spots next to it (besides ice, it is also suggested that it may be salt); as well as craters - there is a large number of cavities in the center. In addition, you can see a mountain with a height of about 5 km and many craters with central peaks, these and other elements provide information about the processes on the surface of a dwarf planet in the past (there is evidence of geological activity) and its internal structure [71] [72] [73 ] .
On August 17, the device switched to the third scientific orbit of 1,470 km for mapping the surface of Ceres and studying the internal distribution of the mass of Ceres using radio waves [74] [75] [76] On August 19, images of the surface of Ceres were obtained from the third scientific orbit with a resolution of 140 m / pixel (which almost 3 times better than in the previous orbit) - a mountain in the southern hemisphere with a height of 6 km [77] . September 9 - detailed pictures of the crater, which contains bright spots, called Occator [74] [78]
On December 8, the probe completed its descent to an altitude of 385 km [79] . After a small planned adjustment of the trajectory of December 11-13, a detailed survey (with a resolution of 35 m / pixel) of surface details, especially the Occator crater, is outlined in the fourth orbit; the study of gamma rays and neutron fluxes to determine the content of certain chemical elements; analysis of the content of various minerals using a VIR spectrometer, as well as studies of the gravitational field over the next three months - until May 2016. In order to maximize the life of the device, the engineers will try to translate the hybrid orientation system using the two remaining flywheels [80] [81] . December 10 - the first photos of the surface (Gerber chains ) taken by the backup camera for testing purposes. Such complex structures on the surface of Ceres are of particular interest, since they indicate a complex surface structure inherent in larger bodies, such as Mars [80]. The first half of 2016, the device takes pictures of the surface of an asteroid.
Further study
On June 30, the device completed its main mission, during which it flew a total of 5.6 billion km, completed 2,450 revolutions around Vesta and Ceres, sent 69,000 images of these two bodies to Earth, and the ion engine worked for 48,000 hours [82] .
July 6, NASA adopted the expanded mission program. Theoretically, the unit could be directed to one of more than 65,000 known objects, but the most promising could be the study of one of the Adeona family asteroids, while the fuel would be spent even more economically. However, after evaluating all the factors, it was decided to leave "Dawn" in the orbit of Ceres for further study [83] [84] .
On October 19, the extended mission for the study of Ceres was extended for the second time until the second half of 2018 [15] [85] .
On November 1, 2018, the vehicle exhausted all supplies of maneuvering and orientation fuel, the Dawn mission, which lasted 11 years, was officially completed [86] .
Summary
The data obtained by “Dawn” revealed an extremely diverse morphology of the surface of Vesta: depressions, ridges, cliffs, hills and a very large mountain were found. A strong dichotomy has been registered, that is, a fundamental difference between the northern and southern hemispheres. The northern one is older and stronger is dug by craters, while the southern one is brighter and smoother, has basalt lithology and at least twice as young as the northern one: its age is estimated at 1-2 billion years, whereas for the oldest elements of the northern relief it is only slightly less than 4 billion years [ 34] . Anomalous dark spots and stripes on the surface correspond to dark inclusions found in meteorites from Vesta and having their origin, most likely, impact events in antiquity [2] . A detailed mineralogical analysis of the surface proved equivalence with the composition of meteorites of the type , which confirms the theory of the formation of the crust by melting the chondrite . Thus, it was finally confirmed that Vesta is the source of HED-meteorites (that is, one of the largest single sources of meteorites on Earth), and the corresponding surface areas were also established - the huge impact basins of Reiasilvius and Venenya near the south pole [87] . The clarification of their age (they turned out to be unexpectedly young) made it possible, in turn, to clarify the theory of the evolution of the solar system as a whole, especially the late heavy bombardment stage [88] . And “Dawn” was thus the first spacecraft to investigate the source of meteorites after their identification on Earth [89] .
Based on measurements of mass, shape, volume, and rotational parameters of Vesta, photographs and radio soundings were determined by Vesta’s dimensions [2] , and the exact distribution of the gravitational field was obtained, indicating early differentiation [87] . The probe data helped scientists reconstruct a picture of the formation and evolution of an asteroid, in particular, the formation of 4.56 billion years ago of a large (average radius from 107 to 113 km [87] ) iron core, just as it happened in the terrestrial planets and the Moon. However, other bodies that had at this stage of the evolution of the solar system were absorbed by these planets, but this did not happen with Vesta, which makes it unique in this respect [88] [89] .
Finally, with the arrival of “Dawn” for Vesta, a new coordinate system had to be developed, as it turned out that the previous one, based on the telescope observations, had an error of almost 10 ° [34] .
Further, these spacecraft data made it possible to clarify in the direction of decreasing the mass and size of Ceres: its equatorial diameter is 963 km, the polar diameter is 891 km, and the mass is 9.393⋅10 20 kg [90] . A gravitational map of Ceres was compiled and many detailed images of its surface were obtained. In addition, the researchers found on Ceres " " suitable for holding water ice for a long time, an ice volcano , traces of organic matter, unusual mountains, disappeared craters, glaciers and landslides, as well as mysterious , the composition of which for a long time could not be established [15] .
By the time the main mission was completed, the apparatus had covered a total of 5.6 billion km, having completed 2,450 revolutions in orbits around Vesta and Ceres. During this time, they collected 132 GB of data, in particular, 69,000 images were captured [82] .
Notes
- 2 1 2 NASA's Dawn Spacecraft Enters Orbit Around Asteroid Vesta , NASA (July 16, 2011). The appeal date is October 2, 2016.
- ↑ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Dawn at Ceres (eng.) . NASA Press Kit / 2015 (2015).
- 2 1 2 NASA Spacecraft Becomes First to Orbit a Dwarf Planet , NASA (March 6, 2015). The appeal date is October 2, 2016.
- 2 1 2 Dawn has Departed the Giant Asteroid Vesta , NASA (September 5, 2012). The appeal date is October 2, 2016.
- 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Marc D. Rayman, Thomas C. Fraschetti, Carol A. Raymond, Christopher T. Russell. Dawn: Vesta and Ceres asteroids; Acta Astronautica. - 2006. - V. 58 . - p . 605-616 . - DOI : 10.1016 / j.actaastro.2006.01.014 .
- ↑ 1 2 3 4 5 6 7 8 9 10 11 I. Lisov. Start AMC "Dawn" . Probe "Dawn" . Project "Exploration of the Solar System" (2007). The appeal date is November 19, 2016.
- ↑ Dawn Frequently Asked Questions (FAQs) (English) . NASA JPL. Archived March 3, 2012.
- ↑ At the time of planning the program of work, Dawn Ceres was officially considered an asteroid.
- ↑ Installation of the names microchip on Dawn (English) . The Bruce Murray Space Image Library . The Planetary Society (May 17, 2007). The appeal date is November 7, 2017.
- ↑ The Camera System - Dawn's Eyes (English) . Max Planck Institute for Solar System Research. The date of appeal is November 4, 2017.
- ↑ Spacecraft and Instruments
- ↑ Dawn Launch - Mission to Vesta and Ceres (English) . NASA Press Kit / September 2007. The date of appeal is July 25, 2016.
- ↑ Dawn probe will not fly to the asteroid
- ↑ Dawn will remain with Ceres
- ↑ 1 2 3 Alexander Voytyuk . The Dawn probe will remain in Ceres orbit forever , N + 1 (Oct 23, 2017). The appeal date is October 24, 2017.
- ↑ Dawn Mission Initiates Newsletter (English) (inaccessible link) . NASA (November 11, 2002). Archived March 3, 2012.
- ↑ Dawn Spacecraft Successfully Launched , NASA (September 27, 2007). The appeal date is October 2, 2016.
- ↑ Dawn Mission Status: Spacecraft Tests Ion Engine , NASA (October 9, 2007). The appeal date is October 2, 2016.
- ↑ NASA's Dawn Spacecraft Begins Interplanetary Cruise Phase , NASA (December 18, 2007). The appeal date is October 2, 2016.
- ↑ Dawn Images the Red Planet , NASA (February 20, 2009). The appeal date is October 2, 2016.
- ↑ 1 2 Dawn Finishes Mars Phase , NASA (February 26, 2009). The appeal date is October 2, 2016.
- НА NASA probe "Dawn" made its first shot of the asteroid Vesta , RIA Novosti (May 11, 2011). The appeal date is May 12, 2011.
- ↑ NASA's Dawn Captures Near Image Of Asteroid , NASA (May 11, 2011). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Mission Status Updates 2011 (English) . Dawn Mission . NASA (May 3, 2011). The appeal date is October 3, 2016.
- ↑ Marc Rayman. Mission Status Updates 2011 (English) . Dawn Mission . NASA (May 10, 2011). The appeal date is October 3, 2016.
- ↑ Dawn Team Members Check out Spacecraft , NASA (July 7, 2011). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Mission Status Updates 2011 (English) . Dawn Mission . NASA (July 1, 2011). The appeal date is October 3, 2016.
- ↑ 1 2 Marc Rayman. Dawn Journal July 18, 2011 (Eng.) . NASA (July 18, 2011). The appeal date is October 13, 2016.
- ↑ Popov, Leonid Terrestrial reconnaissance arrived at the hardest asteroid . membrana.ru (July 15, 2011). Archived March 3, 2012.
- ↑ NASA's Dawn's Spacecraft Views Dark Side of Vesta , NASA (July 28, 2011). The appeal date is October 2, 2016.
- ↑ NASA's Asteroid Photographer Beams Back Science Data , NASA (August 11, 2011). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Mission Status Updates 2011 (English) . Dawn Mission . NASA (11 August 2011). The appeal date is October 3, 2016.
- ↑ Marc Rayman. Dawn Journal August 11, 2011 (Eng.) . NASA (11 August 2011). The appeal date is October 13, 2016.
- ↑ 1 2 3 4 5 A. Ilyin. New data on Vesta . Probe "Dawn" . galspace.spb.ru - Project "The Study of the Solar System." The appeal date is November 12, 2017.
- ↑ Marc Rayman. Mission Status Updates 2011 (English) . Dawn Mission . NASA (September 1, 2011). The appeal date is October 3, 2016.
- ↑ Marc Rayman. Mission Status Updates 2011 (English) . Dawn Mission . NASA (September 20, 2011). The appeal date is November 11, 2017.
- ↑ 1 2 Marc Rayman. Dawn Journal October 31, 2011 (Eng.) . NASA (September 27, 2011). The appeal date is October 13, 2016.
- ↑ NASA's Dawn Spacecraft Begins New Vesta Mapping Orbit , NASA (September 30, 2011). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Mission Status Updates 2011 (English) . Dawn Mission . NASA (September 29, 2011). The appeal date is October 3, 2016.
- ↑ Marc Rayman. Mission Status Updates 2011 (English) . Dawn Mission . NASA (December 8, 2011). The appeal date is November 12, 2017.
- ↑ Marc Rayman. Dawn Journal November 29, 2011 (Eng.) . NASA (November 29, 2011). The appeal date is November 12, 2017.
- ↑ Dawn reached the lowest orbit around Vesta , Lenta.ru (December 13, 2011). (Verified January 11, 2012)
- ↑ The American Dawn interplanetary probe approached the asteroid Vesta at 210 km , cybersecurity.ru (December 13, 2011). (Verified January 11, 2012)
- ↑ Jia-Rui Cook . NASA's Dawn Spirals Down to Lowest Orbit (eng.) , NASA (December 12, 2011). Archived July 22, 2012. (Verified January 11, 2012)
- ↑ Dawn probe sent the first pictures of Vesta from a low orbit , Lenta.ru (December 22, 2011). (Verified January 11, 2012)
- ↑ Jia-Rui Cook . First Low Altitude Images of Vesta ( NASA ) , NASA (December 21, 2011). (Verified January 11, 2012)
- ↑ Marc Rayman. Mission Status Updates 2012 (Eng.) . Dawn Mission . NASA (June 5, 2012). The appeal date is October 4, 2016.
- ↑ Dawn Gets Extra (Time to Explore Vesta NASA JPL (April 18, 2012). Archived June 5, 2012.
- ↑ Marc Rayman. Dawn Journal September 5, 2012 (Eng.) . NASA (May 9, 2012). The appeal date is October 15, 2016.
- ↑ Dawn Delivers New Image of Ceres , NASA (January 19, 2015). The appeal date is October 2, 2016.
- ↑ NASA's Dawn of Spacecraft Captures Best-Ever View of Dwarf Planet , NASA (January 27, 2015). The appeal date is October 2, 2016.
- ↑ Dawn Gets Closer Views of Ceres , NASA (February 5, 2015). The appeal date is October 2, 2016.
- ↑ 1 2 3 4 Marc Rayman. Dawn Journal February 25, 2015 (Eng.) . NASA (February 25, 2015). The appeal date is October 13, 2016.
- ↑ Dawn Captures Sharper Images of Ceres , NASA (February 17, 2015). The appeal date is October 2, 2016.
- Bright 'Bright Spot' on Ceres Has Dimmer Companion , NASA (February 25, 2015). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Mission Status Updates 2015 (Eng.) . Dawn Mission . NASA (February 28, 2015). The appeal date is October 4, 2016.
- ↑ 1 2 Marc Rayman. Dawn Journal March 6, 2015 (English) (inaccessible link) . NASA (6 March 2015). The appeal date is October 15, 2016. Archived September 17, 2016.
- ↑ Marc Rayman. Dawn Journal November 28, 2016 (Eng.) . NASA (November 28, 2016). The appeal date is June 22, 2017.
- ↑ Marc Rayman. Dawn Journal December 29, 2016 (English) . NASA (December 29, 2016). The appeal date is June 22, 2017.
- ↑ Marc Rayman. Dawn Journal January 31, 2017 (English) . NASA (31 January 2017). The appeal date is June 22, 2017.
- ↑ Occator and Ahuna . Dawn Image Gallery . NASA (February 24, 2017). The date of circulation is June 24, 2017.
- ↑ 1 2 Marc Rayman. Dawn Journal April 25, 2017 (English) . NASA (25 April 2017). The appeal date is June 26, 2017.
- ↑ Marc Rayman. Mission Status Updates 2017 (English) . Dawn Mission . NASA (1 May 2017). The date of circulation is June 21, 2017.
- ↑ Marc Rayman. Mission Status Updates 2017 (English) . Dawn Mission . NASA (31 May 2017). The appeal date is June 22, 2017.
- ↑ Chris Gebhardt . Dawn completes historic arrival at Ceres (Eng.) (March 05, 2015). The appeal date is March 6, 2015.
- Month One Month After Ceres Arrival , NASA (April 6, 2015). The appeal date is October 2, 2016.
- ↑ Dawn Enters Science Orbit , NASA (April 24, 2015). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Mission Status Updates 2015 (Eng.) . Dawn Mission . NASA (April 23, 2015). The appeal date is October 4, 2016.
- ↑ Marc Rayman. Mission Status Updates 2015 (Eng.) . Dawn Mission . NASA (April 24, 2015). The appeal date is October 4, 2016.
- ↑ Composite image of Ceres from the Rassvet satellite
- ↑ Bright Spots Shine in Newest Ceres Images , NASA (June 10, 2015). The appeal date is October 2, 2016.
- ↑ Ceres Spots Continue to Mystify in Latest Dawn Images , NASA (June 22, 2015). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Dawn Journal June 29, 2015 . Bright Spots Aren't the Only Mysteries on Dwarf Planet Ceres (English) . NASA (June 29, 2015) . The appeal date is October 15, 2016.
- 2 1 2 Ceres' Bright Spots Seen in Striking New Detail , NASA (September 9, 2015). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Dawn Journal August 21, 2015 . A Sharper Focus on the Exotic World (English) . NASA (August 21, 2015) . The appeal date is October 15, 2016.
- ↑ Marc Rayman. Mission Status Updates 2015 (Eng.) . Dawn Mission . NASA (August 17, 2015). The appeal date is October 5, 2016.
- ↑ Marc Rayman. The Lonely Mountain (Eng.) . Dawn Image Gallery . NASA (August 25, 2015). The appeal date is October 15, 2016.
- ↑ New Names and Insights at Ceres , NASA (July 28, 2015). The appeal date is October 2, 2016.
- ↑ NASA: Dawn's probe came out to the last orbit over Ceres today
- 2 1 2 Lowdown on Ceres: Images From Dawn's Closest Orbit , NASA (December 22, 2015). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Dawn Journal November 30, 2015 . Dawn Begins Descent to Closest and Final Orbit at Ceres (Eng.) . NASA (November 30, 2015) . The appeal date is October 15, 2016.
- ↑ 1 2 Dawn Completes Primary Mission , NASA (June 30, 2016). The appeal date is October 2, 2016.
- ↑ Marc Rayman. Mission Status Updates 2016 (Eng.) . Dawn Mission . NASA (6 July 2016). The appeal date is October 15, 2016.
- ↑ Marc Rayman. Dawn Journal July 27, 2016 (Eng.) . NASA (July 27, 2016). The appeal date is October 15, 2016.
- ↑ Elizabeth Landau . Dawn Mission Extended at Ceres (Eng.) , NASA (Oct. 19, 2017).
- НА NASA's interplanetary station has failed . Lenta.ru (November 2, 2018). The appeal date is November 2, 2018.
- ↑ 1 2 3 CT Russell et. al. Dawn at Vesta: Testing the Protoplanetary Paradigm: [ eng ] // Science. - 2012. - Vol. 336, no. 6082 (11 May). - p. 684-686. - DOI : 10.1126 / science.1219381 .
- ↑ 1 2 Jonathan Amos . Asteroid Vesta , BBC (11 May 2012). The appeal date is November 13, 2017.
- ↑ 1 2 Tony Greicius . NASA Dawn - Mission Reveals Secrets of Large Asteroid (Eng.) , Dawn - A Journey to the Asteriod Belt , NASA (10/05/12). The appeal date is November 14, 2017.
- ↑ Marc Rayman. Dawn Journal May 28, 2015 . Mysteries Unravel as Dawn Circles Closer to Ceres (eng.) . NASA (May 28, 2015) . The appeal date is October 15, 2016.
Links
- Description of AMC "Dawn" on the official website of NASA
- Description AMC "Dawn" on the official site of JPL
- Mission dawn