CERES WAS CLOSER TO THE EARTH ON 2009 FEB 25 AT 6:36 PM EST THAN IT HAD BEEN SINCE 1857

AND WAS WITHIN 148 MILLION MILES UNTIL EARLY ON 2009 MARCH 6

LOOK AT THE FOLLOWING CHART SHOWING THE MINIMUM DISTANCES FOR 3 SPECIAL YEARS:

1857 FEB 14 3:50 PM EST - DISTANCE FROM EARTH - 1.5814695 AU = 147.0007 MILLION MILES

2009 FEB 25 6:36 PM EST - DISTANCE FROM EARTH - 1.5831978 AU = 147.1674 MILLION MILES

2032 FEB 24 4:50 PM EST - DISTANCE FROM EARTH - 1.5847773 AU = 147.3143 MILLION MILES

CERES' PERIOD AROUND THE SUN IS 4.59984 YEARS SO THAT 5 REVOLUTIONS OF CERES IS LESS THAN 2 DAYS SHORT OF 23 EARTH YEARS.

THE CLOSE PASS OF CERES IN 2032 IS 22 YEARS FROM 2010.

HOWEVER, CERES WILL NOT BE AS CLOSE TO EARTH AS IN 2009 UNTIL THE YEAR 4164!

BUT AN EVEN BRIGHTER PASS (MAGNITUDE 6.7) THOUGH MORE DISTANT AT 1.6843 AU WILL OCCUR

ON 2012 DECEMBER 20 DUE TO A MORE DIRECT ALIGNMENT SINCE CERES IS INCLINED 10.607 DEGREES TO OUR ORBIT.

ACTUALLY AFTER ONLY 2 CYCLES YIELDS A VERY NICE VIEW OF CERES IN 2018 CLOSEST ON FEB 1st

1.601857513 AU = 148.902 MILLION MILES. ALSO, IN JEAN MEEUS's BOOK - ASTRONOMICAL TABLES OF

THE SUN, MOON AND PLANETS - on p. 50 LISTS CERES AT A BRIGHTER MAGNITUDE (ONLY 6.7) THAN IN 2009 FOR THE CLOSE PASS ON

2012 DECEMBER 20 - DISTANCE OF 1.6843 AU (156.57 MILLION MILES).

Charts showing the path of Ceres during 2009. Ceres was too close to the Sun for observation from late September to almost the end of the year 2009.

Late 2008 to mid 2009 June and July 2009 August and September 2009

Positions of Ceres in 2009 Other Asteroids

Ceres was at opposition on 25 February 2009 when it was at its brightest, magnitude 6.9. Due to the inclination of its orbit, it was not due north at local midnight until a few days later on 2 March 2009. The asteroid is in conjunction with the Sun on October 2009 Oct 31, and too close to the Sun for observation for about a month or more either side of this date.

On 17 January 2009, Ceres reaches a stationary point in Leo. In the days that follow, Ceres will start moving in a retrograde sense to the west leading up to its opposition. It reaches a second stationary point 3 months later on 2009 April 17 when the westerly movement of Ceres will cease and it will recommence moving in a forward direction to the east.

At the end of October, Ceres is at conjunction with the Sun. As a result the minor planet will not be observable from late September when it will set shortly after the Sun in the evening. After conjunction Ceres will rise in the morning sky before the Sun, but will remain lost in the morning twilight until the very end of December 2009.

At opposition, Ceres will be well north of the equator and so low in the sky for southern hemisphere observers. By the end of March the minor planet will be moving to the south and so get higher in southern skies during the rest of the year. It crosses the celestial equator into the southern hemisphere early in September.

As its number implies, Ceres was the first Minor Planet or Asteroid to be discovered. It was discovered by G. Piazzi at Palermo in Sicily being first seen by him on 1801 January 1st. His biography is just below.

Ceres has a diameter of 932.6 km (573.5 miles) and is easily the largest inner asteroid, although recently a number of larger Kuiper Belt Objects have been discovered. At its 2006 meeting in Prague, the IAU voted that Ceres should be one of the group of "Dwarf Planets". It is the only asteroid that is large enough to be pulled into a spherical shape by its gravity.

Ceres's orbital period is 4.599 years, its distance from the Sun varying between 2.55 and 2.98 AU. The orbit is inclined at 10.6° to the ecliptic.

RASNZ home page

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The Orbit of Ceres

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Astrobiologists hope to find life elsewhere in the universe, or possibly even in our own cosmic neighborhood, the solar system. Their efforts are usually concentrated on worlds such as the planet Mars, or icy moons like Europa. However, there are other, less conventional locations in the solar system where scientists think life may be found.

At the International Society for the Study of the Origin of Life conference in Florence, Italy, Joop Houtkooper from the University of Giessen divulged a theory that life could have originated on the Asteroid Ceres.

The distant world Ceres, the smallest known dwarf planet in the solar system, lies within the asteroid belt. It was called a planet after its discovery in 1801, then later downgraded to asteroid status. With the latest planet definition from the International Astronomical Union, the round object is now considered a dwarf planet. Is there a chance that this exotic world is home to extraterrestrial organisms?

"This idea came to me when I heard a talk about all the satellites in the solar system that consist of a large part of ice, much of which is probably still in a liquid state," says Houtkooper. "The total volume of all this water is something like 40 times greater than all the oceans on Earth."

This reminded Houtkooper of a theory about how life originated. Organisms may have first developed around hydrothermal vents, which lie at the bottom of oceans and spew hot chemicals. Many icy bodies in our solar system have rocky cores, so they may have had or still have hydrothermal vents. Houtkooper realized, "if life is not unique to the Earth and could exist elsewhere, then these icy bodies are the places where life may have originated."

Looking at the Evidence

Early in the history of the solar system was a period known as Late Heavy Bombardment, a turbulent time when cataclysmic asteroid impacts were common. If there was life on Earth before this dangerous era, it was most likely eradicated and had to begin again after much of this cosmic debris had cleared out of the inner solar system. Interestingly, evidence indicates that Ceres avoided being pummelled by devastating impacts during this time. If it had been bombarded, it would have completely and forever lost its water mantle, as its gravitational force is too weak to recapture it. This is probably what happened to the asteroid Vesta, which has a very large impact crater and no water.

"The evidence points to Ceres having remained relatively unscathed during the Late Heavy Bombardment," states Houtkooper. He says this means Ceres still could have "a water ocean where life could have originated early in the history of the solar system."

This leads to an interesting hypothesis. If the Earth was sterilized by colossal impacts, but Ceres hosted life which survived, could the dwarf planet have reseeded our world with life, via rock fragments that chipped off Ceres and then crashed into Earth? Are all organisms on Earth, including humans, descendants of Ceres? This is an idea that Houtkooper had to pursue.

"I looked at the different solar system bodies which either had or currently have oceans," he explains. "The planet Venus probably had an ocean early in its history, but the planet's greater mass means that more force is needed to chip off a piece of the planetary crust and propel it in the direction of the Earth. Smaller objects like Ceres have lower escape velocities, making it easier for parts of it to be separated."

Houtkooper then calculated the orbital paths of candidate planets, moons and asteroids to see which were in the best positions to have pieces successfully reach the Earth, without being intercepted by other objects. Ceres fared favorably in these calculations.

Life on Ceres

Finally, Houtkooper considered the possibility of organisms still being present on Ceres. "In the ocean, there could be life," he suggests. "On the surface, it would be more difficult. But there are some possibilities. There could be hydrogen peroxide-based life, able to withstand the low temperatures." It's not currently known whether hydrogen peroxide is present on Ceres, but nothing rules it out, either.

The thought of Earth being seeded with life from Ceres and creatures existing there today is certainly fascinating, but Houtkooper admits that it is more science fiction than science fact until evidence can be provided. This is naturally difficult to obtain, as Ceres is a small and distant world. Even the best current images contain very little detail, and just show that there are some surface features; what these features are exactly is a mystery. Spectral analyses indicate the presence of clay-like minerals, and Ceres' slightly flattened shape is what we would expect from a world with a rocky core below a layer of water or ice. Ceres is a dwarf planet with many secrets.

Fortunately, this will soon change thanks to NASA's Dawn mission. Launched in 2007, the probe is due to arrive at Ceres in 2015. Once there it will shed light on the mysterious world, and perhaps take photographs of geysers of water erupting from the surface. Its close-up view could indicate whether Ceres really does have the potential for life.

• Video - NASA's Dawn Asteroid Probe Revealed

• Dawn to Split Asteroid Differences

• Defining Planets

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RASNZ home page

NOTE THAT THE CHARTS BELOW ARE DESIGNED FOR THE SOUTHERN HEMISPHERE

SO SOUTH IS UP

THE CHARTS SHOULD BE TURNED UPSIDE DOWN FOR NORTHERN HEMISPHERE USERS

(1) Ceres during 2011

Ceres is at conjunction with the Sun at the end of January and will remain too close to the Sun for viewing until well into March, when it will first be visible in the morning sky shortly before sunrise. Opposition is on September 16 when the asteroid will have a magnitude 7.6 making it an easy binocular object

After opposition Ceres will be visible throughout the evening for the rest of the year, although it will fade to 9th magnitude.

Ceres is stationary on August 1 when it is in Cetus and again on November 12 when in Aquarius. Between these two dates Ceres will move in a retrograde direction, that is to the west, through the stars. This apparent backwards movement is due to the faster moving Earth overtaking the asteroid. Ceres does not of course reverse its orbital direction round the Sun, it moves to the east at all times. The apparent reversal is shown in the second chart. point in Sagittarius. In the days that follow, it will be moving in a retrograde sense to the west leading up to its opposition. After opposition in June, Ceres will become an evening object. It reaches a second stationary point 3 months later on 9 August by which date it will have returned to Ophiuchus. Ceres will then cease moving to the west and recommence moving in a forward direction to the east to re-enter Sagittarius on September 25.

For the rest of the year, Ceres will be moving to the east across Sagittarius. It will pass through the handle of "the teapot" mid November. By the end of December it will set shortly after then Sun and so become lost in the twilit sky.

As its number implies, Ceres was the first Minor Planet or Asteroid to be discovered. It was discovered by G Piazzi at Palermo in Sicily being first seen by him on 1 January 1801.

Ceres has a diameter of 932.6 km and is easily the largest inner asteroid, although recently a number of larger Kuiper belt objects have been discovered. At its 2006 meeting in Prague, the IAU voted that Ceres should be one of the group of "Dwarf Planets". It is the only asteroid that is large enough to be pulled into a spherical shape by its gravity.

Ceres's orbital period is 4.60 years, its distance from the Sun varying between 2.55 and 2.98 AU. The orbit is inclined at 10.6° to the ecliptic.

RASNZ home page

Chart showing the path of Ceres from March to May 2011.

The chart shows the path of Ceres whilst in the morning sky from March to May 2011. in Libra and then Ophiuchus in December 2009 and January 2011. At this time it will be a morning object rising a little before the Sun.

The chart is a southern hemisphere view with north at the bottom and east to the right. Stars to magnitude 9.0 are shown, which is about the limiting magnitude of 50 mm aperture binoculars. Magnitudes are marked (without a decimal point) for stars brighter than 6.5.

The circle on the chart represents a field of view 5° in diameter, a fairly typical field of view for binoculars.

Chart showing the path of Ceres from late May to the end of 2011.

The chart shows the path of Ceres in Aquariues and Cetus from May onwards in 2011. This period includes the time it will be moving in a retrograde sense and when it is at opposition on September 16.

The chart is a southern hemisphere view with north at the bottom and east to the right. Stars to magnitude 9.0 are shown, which is about the limiting magnitude of 50 mm aperture binoculars. Magnitudes are marked (without a decimal point) for stars brighter than 6.5.

The circle on the chart represents a field of view 5° in diameter, a fairly typical field of view for binoculars.

Chart prepared using GUIDE 8.0. Program produced by Project Pluto.

Positional data for Ceres during 2011

Other Asteroids for 2011 RASNZ Home Page

Top of Page Other Asteroids RASNZ Home Page

THE PAGE BELOW IS FROM THE WEBSITE: http://home.comcast.net/~eliws/ceres/

Why? - Documents and Files - Images - Size Comparisons - Other Main Belt Dwarfs - Links - Contact

from Space.com

This web page is a collection of information regarding the Dwarf Planet Ceres. It compiles documents and images from a variety of sources to try and create the most informative website about Ceres on the net. We hope that through this information you will be as informed about Ceres as any professional.

Why should you care about Ceres?

As far as we know, life needs water to survive — and lots of it to thrive. Ceres is the closest large celestial body to Earth which is thought to have an abundance of fresh water. It is also closest to the sun of any large icy body, which along with possible interior heat might warm it enough for subsurface liquid water to exist.

Important criteria for a human outpost in space are available resources. Dozens of probes have been tasked with finding water deposits on the Moon and Mars. Ceres may in fact have more water than we would ever need.

Thus, Ceres would not only be a great place to search for life, but a possible future destination for manned missions and outposts as well.

Ceres is also interesting historically. First it was a Planet, then it was an Asteroid, and now it is a Dwarf Planet. The one mission to Ceres, NASA’s Dawn Mission, was cancelled, reinstated, told to "Stand Down", "Indefinitely Postponed", publicly cancelled, placed under review, and finally reinstated and given a go for launch in June 2007. While Ceres may be one of the gems of our solar system, its nomenclature and single planned mission have had a turbulent past.

Documents and Files

Ceres Hubble Rotation Model (QuickTime Movie)

Dawn Mission Faq (PowerPoint)

Diversity of C-Class Asteroids (PDF)

Keck II AO Ceres (PowerPoint)

Light Curve Models of 20 Asteroids (PDF)

Light Curve Models of 30 Asteroids (PDF)

Reconstructing HST Images of Asteroids (JPEG)

Typical Old Astronomy Book Page (JPEG)

VLT AO Ceres (PDF)

Images (Click on Small Images to Enlarge them)

The first image of Ceres clearly showing its nearly round shape were Ultraviolet Hubble Space Telescope images with 50 km resolution taken in 1995. These showed an enigmatic dark spot which was nicknamed Piazzi after Ceres discoverer.

Better images were obtained in 2002 through use of the Keck II telescope using adaptive optics. Clearly notable are what appears to be a large crater with bright central peak, and a large dark spot. (See Keck II AO Ceres PowerPoint)

Hubble again imaged Ceres in 2003 and 2004. These images were used to create rotational videos and a rotational model. These images show a prominent white spot the nature of which is unknown. (Rotational videos in order: Mid-Ultraviolet, Visible Light, Near-Ultraviolet. See Ceres Hubble Rotation Model movie for model based on this data)

In 2004, Hubble was also able to acquire a color image of Ceres. This shows the prominent crater with central peak in the Northern hemisphere of Ceres seen in the Keck II images as well as the 2004 Hubble rotational videos. (See Color View of Ceres)

In 2004 the Very Large Telescope (VLT) using adaptive optics imaged Ceres. These images show a dark spot in the approximate location the Piazzi feature would be, as well as large brightness asymmetry. (See VLT AO Ceres PDF)

Reconstructed HST Wide-Field/Planetary Camera-2 images of Ceres show a possible water of hydration feature. (See Reconstructing HST Images of Asteroids JPEG)

Artists Conception of Ceres possible differentiated interior. (See article "Largest asteroid might contain more fresh water than Earth")

Size Comparisons

Here we have several size comparisons of Ceres vs. other objects of the solar system. Size charts such as these provoke questions: Could Ceres be geologically active? Miranda, a moon of Uranus is thought to have been active in the past, and Saturn's moon Enceladus is geologically active at present time. Both of these are icy bodies, as is Ceres, and both are smaller than Ceres.

Other Main Belt Dwarf Planets?

If other main belt asteroids could be proven to have attained a nearly round shape, then they too could be considered dwarf planets. This is unlikely however. 4 Vesta perhaps was round at some point in its past, but is now clearly un-spherical with an enormous crater dominating a vast area of its surface. While reconstructed Hubble images of asteroid 10 Hygiea seemed to point to it being spherical, newer light curve models point to a typical "potato asteroid". Light curve shape models of 2 Pallas and 511 Davida indicate distinctly un-spherical bodies, with 2 Pallas being egg-shaped and 511 Davida being potato shaped. Thus based on current available information, all asteroids (other than Ceres) large enough to theoretically pull themselves into a nearly round shape have not, and therefore do not meet the criteria for being classified as a "Dwarf Planet". Many have complained that the requirement of a body being "nearly round" is ambiguous, but clearly objects as irregularly shaped as Vesta, Pallas, Hygiea, and Davida appear to be, could never qualify as "nearly round".

Hubble Space Telescope models of 4 Vesta

Light Curve Models of 2 Pallas (See Light Curve Models Of 30 Asteroids PDF)

Reconstructed HST Image of 10 Hygiea (See Reconstructing HST Images of Asteroids JPEG)

Light Curve Models of 10 Hygiea (See Light Curve Models Of 20 Asteroids PDF)

Light Curve Models of 511 Davida (See Light Curve Models Of 30 Asteroids PDF)

Links

Bad Astronomy and Universe Today Forum (best astronomy forum out there)

The Encyclopedia of Astrobiology, Astronomy, and Spaceflight's entry on Ceres

HubbleSite: Color View of Ceres

Largest asteroid might contain more fresh water than Earth

NASA's Dawn mission to Vesta and Ceres

Selected Asteroids (lots of good information)

The Planetary Society: Asteroid 1 Ceres (an up-to-date summary of knowledge about Ceres)

Solar system's damp start written in asteroid's rock

Squashed asteroid has planet-like qualities

The Symbols and Names of the Asteroids

When Did the Asteroids Become Minor Planets?

Wikipedia Encyclopedia page for Ceres (very helpful)

Wikipedia list of noteworthy asteroids

Wikipedia entry for the Dawn Mission

Website design © 2006 esdesign - Last updated 2006.09.20

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WIKIPEDIA BIOGRAPHY OF GIUSEPPE PIAZZI - THE DISCOVERER OF CERES

Giuseppe Piazzi (July 7, 1746 - July 22, 1826) was an Italian Theatine monk, mathematician, and astronomer. He was born in Ponte in Valtellina, and died in Naples. He established an observatory at Palermo, now the Osservatorio Astronomico di Palermo – Giuseppe S. Vaiana^[1].

Biography

No documented account of Piazzi's scientific education is available in any of the biographies of the astronomer, even in the oldest ones. Piazzi certainly did some studies in Torino, quite likely attending Giovan Battista Beccaria's lessons. In the years 1768-1770 he was resident at the Theatines' Home in S. Andrea della Valle, Rome, whilst studying Mathematics under Francesco Jacquier. In July 1770 he took the chair of Mathematics at the University of Malta. In December 1773 he moved to Ravenna as "prefetto degli studenti" and lecturer in Philosophy and Mathematics at the Collegio dei Nobili, where he stayed until the beginning of 1779. After a short period spent in Cremona and in Rome, in March 1781 Piazzi moved to Palermo as lecturer in Mathematics at the University of Palermo (at the time known as "Accademia de' Regj Studi"). He kept this position until 19 January 1787, when he became Professor of Astronomy. Almost at the same time he was granted permission to spend two years in Paris and London in order to undergo some practical training in astronomy and also to get some instruments to be specially built for the Palermo Observatory, whose foundation he was in charge of. In the period spent abroad, from 13 March 1787 until the end of 1789, Piazzi became acquainted with the major French and English astronomers of his time and was able to have the famous altazimuthal circle made by Jesse Ramsden, one of the most skilled instrument-makers of the XVIII century. The circle was the most important instrument of the Palermo Observatory, whose official foundation took place on 1 July 1790. In 1817 King Ferdinand put Piazzi in charge of the completion of the Capodimonte (Naples) Observatory, naming him General Director of the Naples and Sicily Observatories.

Astronomy Career

Star Cataloguing

He supervised the compilation of the Palermo Catalogue of stars, containing 7,646 star entries with unprecedented precision^[2], including the star names "Garnet Star" from Herschel, and the originalRotanev and Sualocin. The work on this catalogue was started in 1789, enabling Piazzi and collaborators to observe the sky methodically. The catalogue wasn't finished for first edition publication until 1803.

Spurred by the success discovering Ceres (see below), and in the line of his catalogue program, Piazzi studied the proper motions of stars in order to find parallax measurement candidates. One of them, 61 Cygni, was specially appointed as a good candidate for measuring a parallax, which was later performed by Friedrich Wilhelm Bessel^[3]. The star system 61 Cygni is sometimes still called variously Piazzi's Flying Star and Bessel's Star.

The Asteroid Ceres

Piazzi discovered the Ceres, today known as the largest member of the asteroid belt. On January 1, 1801, Piazzi discovered a "stellar object" that moved against the background of stars. At first he thought it was a fixed star, but once he noticed that it moved, he became convinced it was a planet, or as he called it, "a new star".

In his journal, he wrote: "The light was a little faint, and of the colour of Jupiter, but similar to many others which generally are reckoned of the eighth magnitude. Therefore I had no doubt of its being any other than a fixed star. In the evening of the second I repeated my observations, and having found that it did not correspond either in time or in distance from the zenith with the former observation, I began to entertain some doubts of its accuracy. I conceived afterwards a great suspicion that it might be a new star. The evening of the third, my suspicion was converted into certainty, being assured it was not a fixed star. Nevertheless before I made it known, I waited till the evening of the fourth, when I had the satisfaction to see it had moved at the same rate as on the preceding days."

In spite of his assumption that it was a planet, he took the conservative route and announced it as a comet. In a letter to astronomer Barnaba Oriani of Milan he made his suspicions known in writing:

"I have announced this star as a comet, but since it is not accompanied by any nebulosity and, further, since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet. But I have been careful not to advance this supposition to the public."

He was not able to observe it long enough as it was soon lost in the glare of the Sun. Unable to compute its orbit with existing methods, the renowned mathematician Carl Friedrich Gauss developed a new method of orbit calculation that allowed astronomers to locate it again. After its orbit was better determined, it was clear that Piazzi's assumption was correct and this object was not a comet but more like a small planet. Coincidentally, it was also almost exactly where the Titius-Bode law predicted a planet would be.

Piazzi named it "Ceres Ferdinandea", after the Roman and Sicilian goddess of grain and King Ferdinand IV of Naples and Sicily. The Ferdinandea part was later dropped for political reasons. Ceres turned out to be the first, and largest, of the asteroids existing within the Asteroid Belt. Ceres is today called a dwarf planet.

Posthumous Honors

In 1923, the 1000th asteroid to be numbered was named 1000 Piazzia in his honor. The lunar crater Piazzi was named after him in 1935. More recently, a large albedo feature, probably a crater, imaged by the Hubble Space Telescope on Ceres, has been informally named Piazzi.

See Also

• Niccolò Cacciatore, his assistant and successor on the post as director

References

1. ^ Osservatorio astronomico di Palermo – Giuseppe S. Vaiana

2. ^ DavidDarling.com: Piazzi, Giuseppe (1746-1826)

3. ^ On the history of the Palermo Astronomical Observatory by Giorgia Foderà Serio

• Cunningham, C. J. (2001). The First Asteroid. Star Lab Press. ISBN 0-9708162-2-7.

• Foderà Serio, G.; Manara, A.; Sicoli, P. (2002). "Giuseppe Piazzi and the Discovery of Ceres". in W. F. Bottke Jr., A. Cellino, P. Paolicchi, and R. P. Binzel (PDF). Asteroids III. Tucson, Arizona: University of Arizona Press. pp. 17–24. http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3027.pdf.

External Links

• Catholic Encyclopedia entry for Giuseppe Piazzi

• Works by or about Giuseppe Piazzi in libraries (WorldCat catalog)

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November 16th, 2009 from UniverseToday.com

Dawn Takes up Residence in Asteroid Belt

Written by Nicholos Wethington

FOR MORE INFORMATION GO TO: http://dawn.jpl.nasa.gov/mission/live_shots.asp

THE DAWN MISSION TO VESTA AND CERES

FROM WIKIPEDIA.COM

Dawn is a robotic spacecraft sent by NASA on a space exploration mission to the two most massive members of the asteroid belt: the asteroid Vesta and the dwarf planet Ceres. Launched September 27, 2007, Dawn is scheduled to explore Vesta between 2011 and 2012, and Ceres in Feb. 2015. It will be the first spacecraft to visit either body.

Dawn is innovative in that it will be the first spacecraft to enter into orbit around a celestial body, study it, and then re-embark under powered flight to proceed to a second target. All previous multi-target study missions—such as the Voyager program—have involved rapid planetary flybys.

The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington.

Launch

Dawn was scheduled to launch from pad 17-B at the Cape Canaveral Air Force Station on a Delta 7925-H rocket.^[2] On April 10, 2007, Dawn arrived at the Astrotech Space Operations subsidiary of SPACEHAB, Inc. in Titusville, Florida, where it was prepared for launch.^[3][4] Launch was originally scheduled for June 20, but was delayed until June 30 due to delays with part deliveries.^[5] A broken crane at the launch pad, used to raise the solid rocket boosters, delayed the launch for a week, until July 7, but on June 15 the second stage was successfully hoisted into position.^[6][7] A mishap at the Astrotech Space Operations facility, involving slight damage to one of the solar arrays, did not have an effect on the launch date, however bad weather caused the launch to slip to July 8. Range tracking problems then delayed the launch to July 9, and then July 15, before the launch was delayed further to avoid knock-on delays with the Phoenix mission to Mars, which was successfully launched on August 4.

Launch of Dawn was then rescheduled for September 26, 2007.^[8][9] However the launch was then delayed to September 27, due to bad weather delaying fuelling of the second stage, the same problem which had earlier delayed the July 7 launch attempt. The launch window extended from 7:20 a.m. - 7:49 a.m. EDT (11:20 - 11:49 GMT).^[10] During the final built-in hold at T-4 minutes, a ship entered the exclusion area offshore, the sea strip where the rocket boosters are likely to fall after separation. The ship was commanded to leave the area, then the launch had to wait for the end of a collision avoidance window with the ISS.^[11]The spacecraft finally launched on Sept 27 at 7:34 a.m. EDT from pad 17-B on a Delta II launch vehicle.^[12][13][14]

The launch rocket propelled Dawn to 11.46 kilometers per second (25,600 miles per hour) relative to earth.^[15] Thereafter Dawn's ion thrusters took over.

Status

After initial checkout, during which the ion thrusters accumulated more than 11 days of thrust, Dawn began long-term cruise propulsion on December 17, 2007.^[16] On October 31, 2008, Dawn completed its first thrusting phase to send it on to Mars for a gravity assist flyby in February 2009. During this first interplanetary cruise phase Dawn has spent 270 days, or 85% of this phase using its thrusters. It has expended less than 72 kilograms (158 pounds) of Xenon propellant for a total change in velocity of 1.81 kilometers per second (4050 miles per hour). On November 20, 2008, Dawn performed its first trajectory correction maneuver (TCM1), firing its #1 thruster for 2 hours, 11 minutes. Following Dawn's solar conjunction, an originally scheduled course correction maneuver in January 2009 was determined not necessary.

Dawn made its closest approach (549 km) to Mars on February 17, 2009 during a successful gravity assist.^[17][18] On this day the spacecraft placed itself in safe mode resulting in some data acquisition loss. The spacecraft was reported to be back in full operation two days later with no impact to the subsequent mission. The root cause of the event was reported to be a software programming error.^[19]

Mission

The mission's goal is to characterise the conditions and processes of the solar system's earliest epoch by investigating in detail two of the largest protoplanets remaining intact since their formation. Ceres and Vesta have many contrasting characteristics that are thought to have resulted from them forming in two different regions of the early solar system; Ceres is theorized to have experienced a "cool and wet" formation that may have left it with subsurface water, and Vesta is theorised to have experienced a "hot and dry" formation that resulted in a differentiated interior and surface volcanism.

Using two redundant framing cameras,^[20] a visual and infared spectrometer, and a Gamma Ray and Neutron Spectrometer,^[21] Dawn will take pictures and measure the chemical composition of Ceres and Vesta.^[22]

To cruise from Earth to its targets it will travel in a long outward spiral.

• CURRENT ESTIMATED CHRONOLOGY IS AS FOLLOWS:^[23]

• September 27, 2007: launch

• February 17, 2009: Mars gravity assist

• July 2011: Vesta arrival

• July 2012: Vesta departure

• February 2015: Ceres arrival

• July 2015: End of operations

NASA posts the Current Location of Dawn on the Web.^[24]

An extended mission in which Dawn explores other asteroids after Ceres is also possible, although unlikely, as greater return is expected by spending the available time at Vesta and Ceres.^[25]

Mission Team

The Dawn mission team is led by UCLA space scientist and Dawn Principal Investigator Christopher T. Russell. NASA's Jet Propulsion Laboratory provided overall planning and management of the mission, the flight system and scientific payload development, and provided the Ion Propulsion System. Orbital Sciences Corporation provided the spacecraft, its first interplanetary mission. The German Aerospace Center (DLR) and the Max Planck Institute for Solar System Research provided the framing cameras, the Italian Space Agency provided the mapping spectrometer, and the DOE Los Alamos National Laboratory provided the gamma ray and neutron spectrometer.^[26]

Motivation

Dawn is intended to study two large bodies in the asteroid belt in order to answer questions about the formation of the solar system.

Ceres and Vesta were chosen as two contrasting protoplanets, one apparently "wet" (that is, icy) and the other "dry" (or rocky), whose accretion was terminated by the formation of Jupiter. They provide a bridge in our understanding between the formation of rocky planets and the icy bodies of our solar system, and under what conditions a rocky planet can hold water.

The IAU adopted a new definition of planet on August 24, 2006, and thus, if the IAU's definition stands and the spacecraft experiences no delays, Dawn will become the first mission to study a dwarf planet, arriving at Ceres five months prior to the arrival of New Horizons at Pluto.

Ceres is a dwarf planet whose mass comprises about one-third of the total mass of the bodies in the asteroid belt and whose spectral characteristics suggest a composition similar to that of a water-rich carbonaceous chondrite. Smaller Vesta, a water-poor achondritic asteroid, has experienced significant heating and differentiation. It shows signs of a metallic core, a Mars-like density and lunar-like basaltic flows.

Both bodies formed very early in the history of the solar system, thereby retaining a record of events and processes from the time of the formation of the terrestrial planets. Radionuclide dating of pieces of meteorites thought to come from Vesta suggests that Vesta differentiated quickly, in only three million years. Thermal evolution studies suggest that Ceres must have formed a little later, more than three million years after the formation of CAIs (the oldest known objects of Solar System origin).

Moreover, Vesta is the source of many smaller objects in the solar system. Most (but not all) V-type near-Earth asteroids, and some outer main-belt asteroids have spectra similar to Vesta and are known as 'vestoids'. Five percent of the found meteoritic samples on Earth, the Howardite Eucrite Diogenite ("HED") meteorites, are thought to be the result of a collision or collisions with Vesta.

Mission Cancellations and Reinstatements

The status of the Dawn mission has changed several times. In December 2003, the project was first cancelled,^[27] and then reinstated in February 2004. In October 2005, work on Dawn was placed into "stand down" mode. In January 2006, Dawn's "stand down" was discussed in the press as "indefinitely postponed", even though NASA had announced no new decisions regarding the mission's status.^[28] On March 2, 2006, Dawn was publicly, but not formally cancelled by NASA headquarters.^[29]

However, the spacecraft's manufacturer Orbital Sciences Corporation appealed the decision and offered to build the spacecraft at cost, forgoing any profit in order to gain experience in a new market field. NASA then put the cancellation under review,^[30] and on March 27, 2006, it was announced that the mission would not be cancelled after all.^[31][32] In the last week of September 2006, the Dawn mission instrument payload integration reached a full functional status.

Propulsion System

The Dawn spacecraft is propelled by three DS1 heritage xenon ion thrusters (firing only one at a time). They have a specific impulse of 3100 s and produce a thrust of 90 mN.^[33] The whole spacecraft, including the ion propulsion thrusters, is powered by a 10 kW triple-junction photovoltaic solar array.^[34] To get to Vesta, Dawn will use 275 kg (606 lb) Xe and another 110 kg (243 lb) to get to Ceres,^[35] out of a total of 425 kg (937 pounds) of on-board propellant.^[36] All in all, it will perform a velocity change of over 10 km/s, far more than any other spacecraft has done.^[35] Dawn is NASA’s first purely exploratory mission to use ion propulsion engines.^[37]

The Dawn Microchip

Onboard Dawn is a small computer microchip bearing the names of more than 360,000 space enthusiasts.^[38] The names were submitted online as part of a public outreach effort between September 2005 and November 4, 2006.^[39] The microchip (about the size of a nickel) was installed above the forward ion thruster, underneath the spacecraft's High Gain Antenna, on May 17, 2007.^[40] More than one microchip was made, with a back-up copy on display at the 2007 Open House at the Jet Propulsion Laboratory in Pasadena, California.

References and Notes

• 1. ^ Dawn Spacecraft Successfully Launched Sept 27, 2007

  2. ^ "Expendable Launch Vehicle Status Report". NASA. 2007-05-11. http://www.nasa.gov/centers/kennedy/launchingrockets/status/2007/elvstatus-20070511.html.

  3. ^ NASA. "Dawn arrives in Florida". Spaceflight Now. http://www.spaceflightnow.com/news/n0704/10dawnarrival/.

  4. ^ "Dawn at Astrotech's Payload Processing Facility". Space and Astronautics News. http://www.space.gs/11-apr-2007-dawn.html.

  5. ^ "Launch of Dawn asteroid mission postponed again". NewScientistSpace. http://space.newscientist.com/article/dn12215-launch-of-dawn-asteroid-mission-postponed-again.html.

  6. ^ "Pad 17 crane to be fixed mid-week". Florida Today. http://www.floridatoday.com/floridatoday/blogs/spaceteam/2007/06/pad-17a-to-be-fixed-mid-week.html.

  7. ^ "Expendable Launch Vehicle Status Report". June 18, 2007. http://www.nasa.gov/centers/kennedy/launchingrockets/status/2007/elvstatus-20070618.html.

  8. ^ "NASA Mission to Asteroid Belt Rescheduled for September Launch". NASA. July 7, 2007. http://www.nasa.gov/mission_pages/dawn/news/HQ_07150_Dawn_postpone_Sep.html.

  9. ^ "Dawn Launch Date". NASA launch schedule. http://www.nasa.gov/missions/highlights/schedule.html. Retrieved 2007-09-01.

  10. ^ "Expendable Launch Vehicle Status Report". NASA. September 7, 2007. http://www.nasa.gov/centers/kennedy/launchingrockets/status/2007/elvstatus-20070907.html.

  11. ^ "NASA's Launch Blog". NASA. September 27, 2007. http://www.nasa.gov/mission_pages/dawn/launch/launch-blog.html.

  12. ^ "ULA—One Team for Assured Access to Space" (PDF). ulalaunch.com. http://www.ulalaunch.com/images/product_sheet/Delta_Product_Sheet_FINAL.pdf. Retrieved 2008-03-04.

  13. ^ "NASA's Launch Coverage". NASA. September 27, 2007. http://www.nasa.gov/mission_pages/dawn/launch/index.html.

  14. ^ "Dawn Spacecraft Successfully Launched". NASA. http://www.nasa.gov/mission_pages/dawn/news/dawn-20070927.html.

  15. ^ http://www-ssc.igpp.ucla.edu/dawn/DawnJournal_24August08.html

  16. ^ Rayman, Marc D.. "Dawn Journal: December 17, 2007". JPL. http://dawn.jpl.nasa.gov/mission/journal_12_17_07.asp.

  17. ^ Dawn Journal: Aiming away from a bull's eye at Mars

  18. ^ Asteroid-Bound Probe Zooms Past Mars at Space.com

  19. ^ "Dawn Receives Gravity Assist from Mars". NASA/JPL. 2009-02-28. http://dawn.jpl.nasa.gov/mission/status.asp.

  20. ^ Framing Camera for Dawn

  21. ^ Science Payload

  22. ^ GRaND science instrument moves closer to launch from Cape

  23. ^ GSpace Topics: Dawn

  24. ^ http://neo.jpl.nasa.gov/orbits/fulltraj.jpg

  25. ^ "Frequently asked questions". NASA. http://dawn.jpl.nasa.gov/mission/faqs.asp#. Retrieved 2008-07-14.

  26. ^ Rayman M. D., Fraschetti T. C., Raymond C. A., Russell C. T. (2006). "Dawn: A mission in development for exploration of main belt asteroids Vesta and Ceres". Acta Astronautica 58 (11): 605–616. doi:10.1016/j.actaastro.2006.01.014.

  27. ^ Ambrosiano, Nancy (2006-03-28). "NASA's Dawn mission is a go". Los Alamos National Laboratory. http://www.lanl.gov/news/index.php/fuseaction/nb.story/story_id/8140. Retrieved 2007-10-01.

  28. ^ Chang, Alicia (2006). "NASA Asteroid Mission Won't Launch This Year". Space.com. http://www.space.com/missionlaunches/ap_060121_dawn_hold.html. Retrieved 2006-03-04.

  29. ^ Clark, Stephen (2006). "Probe built to visit asteroids killed in budget snarl". Spaceflightnow.com. http://www.spaceflightnow.com/news/n0603/03dawn/. Retrieved 2006-03-04.

  30. ^ "NASA reviewing canceled mission". CNN.com. March 16, 2006. http://www.cnn.com/2006/TECH/space/03/16/asteroid.mission.ap/index.html. Retrieved 2006-03-27.

  31. ^ Geveden, Rex (2006). "Dawn Mission Reclama" (PDF). http://www.nasa.gov/pdf/145511main_Dawn_letter.pdf. Retrieved 2006-03-27.

  32. ^ Malik, Tariq (27 March 2006). "NASA Reinstates Cancelled Asteroid Mission". Space.com. http://space.com/news/060327_dawn_mission.html. Retrieved 2006-03-27.

  33. ^ "Dawn, Ion Propulsion". NASA. http://dawn.jpl.nasa.gov/mission/ion_prop.asp. Retrieved 2007-09-28.

  34. ^ "Dawn, Spacecraft". NASA. http://dawn.jpl.nasa.gov/mission/spacecraft.asp. Retrieved 2007-09-28.

  35. ^ ^{a b} "Dawn: Mission description". UCLA Space Physics Center. 2006-10-17. http://www-ssc.igpp.ucla.edu/dawn/mission.html. Retrieved 2007-09-28.

  36. ^ Watanabe, Susan (2007-07-05). "Dawn: Spacecraft & Instruments". NASA. http://www.nasa.gov/mission_pages/dawn/spacecraft/. Retrieved 2006-08-10.

  37. ^ "Dawn Lifts Off". National Geographic Society. http://news.nationalgeographic.com/news/2007/09/photogalleries/wip-week48/. Retrieved 2007-09-28.

  38. ^ "All Aboard the Dawn Spacecraft". JPL.NASA.gov. May 20, 2007. http://dawn.jpl.nasa.gov/DawnCommunity/index.asp. Retrieved 2007-06-21.

  39. ^ "Send Your Name to the Asteroid Belt". JPL.NASA.gov. November 4, 2006. http://dawn.jpl.nasa.gov/DawnCommunity/Sendname2asteroid/index_asteroid_blt.aspx. Retrieved 2007-06-21.

  40. ^ "Kennedy Media Gallery". KSC.NASA.gov. May 17, 2007. http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=32165. Retrieved 2007-06-21.

See Also

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Spacecraft missions to Mars

Bold italics indicates active missions

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National Aeronautics and Space Administration (NASA)

Retrieved from "http://en.wikipedia.org/wiki/Dawn_(spacecraft)"

Categories: Asteroids | Ceres | Spaceflights | Discovery program | NASA probes | Unmanned spacecraft