Fig. 01: Before 2015 these were the best images available of the dwarf planet 1 Ceres taken from the Hubble Space Telescope in 2004. They almost appear like a 19th century view on Mars - vague and mysterious. However the numerous bright spots found on Ceres were first made visible then. The one formally known as Spot 01 is now officially named Haulani - top two images. Even post DAWN's arrival at Ceres in 2015 it is still unclear what these bright spots actually are. However it seems likely that they are areas of exposed sub-surface ice from minor impacts thus giving rise to sublimation from water ice. In 2013 water vapor ejection from the surface was observed from the European - Herschel Space Observatory pointing to a tenuous atmosphere at Ceres. Equatorial surface temperatures can reach minus 38 Celsius during the mid day period. Since the arrival of NASA's unmanned DAWN mission in 2015 greater surface details are now being revealed.

The dwarf planet Ceres has fascinated me for a long time now. In 1980 as a 12 years old I "discovered" it in a school atlas of the Solar System and ever since then I guess I have been under its ever so slight gravitational pull. In about 1981 watching late night TV, after Blakes Seven, I saw for the first time the 1959 episode of the Twilight Zone: The Lonely. The program is about a convicted criminal named James A Corry sentenced to 50 years solitary confinement on a remote asteroid 9 million miles from the Earth for a crime he committed in self defense. There he is routinely visited by a supply ship Captained by the sympathetic Allan Bee who at one point gives Corry a very special gift - a robot in the form of a female companion named Alicia. Low budget and even in the minds eye of a 12 year old living in distant Australia it was clearly evident that they had shot it in Death Valley, or some such place, which it turned out to be (Zabriskie Point / Desolation Canyon). While there is no reference in this classic TV drama that the main character Corry is spending his penal sentence on Ceres he is indeed on an asteroid which has nothing for 6000 miles wherever one goes north to south nor 4000 miles east to west! In spite of the fact that these great distances have little in common to 1Ceres, when I saw this TV drama for the first time all those years ago there was no doubt in my mind that Corry was indeed on Ceres! The distances do however imply he is on an oblate spheroid! Coincidentally and about 3 decades later I was recommended by a friend to watch on DVD the little known, but highly entertaining cult movie The American Astronaut, which was directed by who other than a certain Cory McAbee. 

Lastly in the 2015 sci fi series - The Expanse, its set in the asteroid belt and on Ceres. The story is based on the series of novels by James S.A. Corey - the pen name used by collaborators Daniel Abrahams and Ty Franck. The first and last name are taken from Abraham's and Franck's middle names, respectively, and S.A. are the initials of Abraham's daughter.

Somewhere in the Twilight Zone here! It can be no coincidence that the above authors were not also under the gravitational influence of a distant dwarf planet and had been inspired by The Lonely to set their respective seminal films on Ceres! Ceres is no longer a lonely and former asteroid in the expansive void of space. Now I want to present some scenarios about a special place in the minds of some for quite a while now with my blog the Cererian Sentinel.

Figs. 02: On February 19th 2015 the first detailed images of Ceres were captured from the approach of the NASA Dawn probe - showing two hemispheric views. The left view is centered on a shallow, multiple sided and 300 km diameter basin - know as Kerwan. While the right image centers on a prominent bright spot with a radial expanse it now known as Haulani. 
   File:Ceres Orbit.svg

Fig. 03: 1 Ceres is located in the main asteroid belt between the planets Mars and Jupiter. While it is two and a half times the distance from the Sun to Earth solar power is still practical. Nonetheless the surface would only receive approx. one ninth of the Sun light which Earth receives.

Radius (km) 482.6 x 480.6 x 445.6 

Area (km2) 2.77 million

Density (g/cm3) 2.16

Mass 0.00015 Earths

Rotation Period (h) 9.074

Surface Gravity (m/s) 0.28

Semi-Major Axis 2.76 AU

V-band Geometric Albedo 0.090

Surface Temp: mean - 168 K / max - 235 K  

Fig. 04 - Simple cylindrical projection of Ceres giving nomenclature as at October 2015. Only 12 months before almost all features were not as yet discovered let alone names given, this said it was agreed that features would derive their names from agricultural deities and festivals. This DAWN image is centred at the meridian. Just north of the equator can be found the Haulani crater - once referred to as Bright Spot 1. This crater was named after Haulani, the Hawaiian goddess of plants. Located at N 20 degrees / E 239 can be found Occator formally known as Bright Spot 5 and banded at Region A. The crater was named after Occator, the Roman god of the harrow and a helper to Ceres. The crater Kerwan is named after the Hopi spirit of sprouting maize, Kerwan. The crater Dantu was named after the timekeeper and first god of planting millet of the Ga people of Accra, Ghana. Urvara the third largest crater found on 1 Ceres is named after the ancient Indo-Iranian personification of fertility (plants in the Avesta and fertile fields in the Rig Veda). Jarimba is Arunta - Central Australian Aboriginal peoples god of flowers and fruit.

Below I have copied an excellent document from the web authored by Andrew Rivkin and even though it was written long before the NASA DAWN probe arrived at Ceres it still holds gravity. 

The Case for Ceres: Report to the Planetary Science

Decadal Survey Committee

Unresolved, High-Priority Ceres Science Questions

The current state of Ceres research shows it to be a unique object, potentially holding keys to understanding of disparate solar system populations in multiple disciplines. We have identified the following as important science questions concerning Ceres: How did it form and evolve and what is its present-day state?

1) Did Ceres form near its present position or was it transported from the outer solar system? What were Ceres’ starting materials? How much mixing occurred between different planetesimal and protoplanet reservoirs to create Ceres? 

Since the last decadal survey, dynamicists have recognized that the jovian planets may have migrated early in solar system history due to the cumulative effects of scattering small bodies, constructing a scenario called the “Nice Model” incorporating the consequences. The Nice Model predicts that objects that formed beyond Neptune could have been transported to the inner solar system in large numbers, populating Jupiter’s Trojan clouds and providing the D-class objects found in the outer asteroid belt (Levison et al. 2009). Ceres’ low density implies an ice to rock ratio comparable to TNOs. This, plus consideration of the Nice Model and the relative frequency of Ceres-sized objects in the inner and outer solar system, led McKinnon (2008) to suggest the possibility that Ceres itself was formed as a TNO and later brought to its current orbit. While the most straightforward history for Ceres includes formation near its current location and kinship to other C-class asteroids, establishing Ceres’ birthplace will be necessary to fully understand its context. The origin of Ceres has direct implications for its long-term evolution as it determined Ceres’ content in volatiles and accretion time frame (which determines the amount of accreted short-lived radioisotopes.) Means to test this hypothesis are given below.

2) What is the nature of Ceres' interior? Is it differentiated? Does it have an iron core? Does it still support liquid water (within an icy shell)? 

Ceres’ shape can be explained by either a differentiated or undifferentiated internal structure. Thermal evolution models indicate that a differentiated interior is the most likely outcome for Ceres (e.g., McCord & Sotin 2005; Castillo-Rogez & McCord, 2009). Conversely, Zolotov (2009) has recently argued that Ceres’ density and shape remain uncertain and do not preclude an undifferentiated interior. For example, Ceres’ low density may be due to a high-porosity interior, since its internal pressures are not sufficient to ensure extensive compaction. Furthermore, Zolotov used geochemical arguments to conclude that the surface composition of Ceres would be different if it had an internal ocean, one able to erupt to the surface. Understanding Ceres’ interior and validating these models will be invaluable for comparative planetological studies of Ceres and other large low-albedo asteroids (like Pallas, Hygiea, or Cybele) and similar-sized icy satellites (like Tethys, Dione, or Ariel) to delimit the phase space where differentiation can be expected, among other comparisons. As an example, the existence of the Main Belt Comets and their association with the Themis asteroid family shows that ice still exists in those bodies (Hsieh and Jewitt 2006). Modeling may ultimately demonstrate whether the ice within these comets is essentially primordial or whether, in contrast, the Themis family parent body was Ceres-like before breakup.

3) What is the geological history of Ceres? Did Ceres experience cryovolcanism? If so, how long did it persist? How much material was exchanged between Ceres’ interior and surface? Were there periods when Ceres’ surface was icy? Or will Ceres be revealed as geologically dead? What will Ceres’ cratering record tell us about its surface and near sub-surface? 

If Ceres is differentiated, the melting and freezing of its volatile component would have resulted in tectonic activity (e.g. faulting). The low ice viscosity resulting from the relative warmth of Ceres’ surface may have led to geologically rapid relaxation of impact craters and other topographic features, especially near Ceres’ equator, where temperatures are highest (Ceres’ obliquity is very low). Similar to Europa, Ceres may be undergoing resurfacing possibly in the form of cryovolcanism or venting of water vapor (Li et al. 2006). The slow freezing of an internal ocean, as Ceres’ radiogenic heat wanes, in particular should lead to extensional stresses at the planet’s surface, which would be conducive to such eruptions or venting.

4) What is the nature and origin of Ceres' present surface? Is it primordial rock+ice crust that somehow avoided foundering or was re-exhumed? Or is it a deposit of rocky material that was brought to the surface by water or ice, and left after the ice sublimed or was sputtered away? How has space weathering affected Ceres’ surface? What are the as-yet unidentified constituents of its surface? 

Ceres is unique as an ice-rich body with a surface on which ice is unstable. It is unclear whether the current surface of Ceres is a lag deposit of a former (frozen) ocean surface or the non-ice remains of cryovolcanic flows. Another possibility is that it retains remnants of an original mixed rock-ice crust that managed to escape foundering, or which was exhumed after overlying ice was removed by sublimation. We have an incomplete understanding of Ceres’ surface composition. While carbonates and brucite have been identified on Ceres’ surface, there are other absorption bands that have not been associated with specific minerals. A broad band in the near-infrared, also seen in some carbonaceous chondrites, could be due to either magnetite (Fe3O4) or phyllosilicates. Features in the mid-IR have been seen at some times but not others, while interpretation of an absorption consistently seen in the UV has been hampered by a lack of laboratory spectra of analog materials at the relevant wavelengths. Conceivably, the mineralogy on Ceres’ surface could support or refute the hypothesis that Ceres formed farther out in the Solar System.

5) What is the astrobiological potential for Ceres, and/or its complement of prebiotic material? What are the potential mechanisms and frequency of materials recycling and renewal that may affect the potential habitability of Ceres surface or interior? What are the potential geochemical pathways for the transformation and synthesis of indigenous Cerean organic species, now or in the past? 

Only in the last few years have we realized that Ceres is a site of astrobiological significance. It has experienced aqueous alteration, it has carbon-bearing species and its pre-alteration assemblage was likely organic-rich. It is apparently ice-rich, and liquid water may persist to this day. Understanding the interactions of organics and water in Ceres’ interior and near-surface may also provide valuable insight into the prebiotic material available for Earth’s accretion. Ceres’ surface composition identified by Milliken and Rivkin (2009) indicates conditions that are much less oxidizing than Mars, and less reducing than Titan, both of which have been considered as key astrobiological targets (Shapiro and Schulze-Makuch 2008). This oxidation state may result in key differences from the chemical reactions found on Mars and Titan, making Ceres’ evolution more pertinent to Earth’s than either of the former objects.

6) Does Ceres have an appreciable atmosphere or exosphere? If so, what is its composition, and is it largely caused by outgassing, sputtering, or other processes? Can its composition constrain Ceres’ origin and internal structure? If Ceres has no such atmosphere or exosphere, what does that imply about its interior and/or volatile content? 

Observations of Ceres by the International Ultraviolet Explorer (IUE) by A’Hearn et al. (1992) provided hints of –OH emission off of Ceres’ sunlit pole. These were interpreted as possible evidence of ice sublimation. Since the end of IUE, repeating these observations has been difficult, though ground based work with improved sensitivity over IUE found no emission (Rousselot et al. 2008). The possibility of near-surface ice (Fanale and Salvail 1989) and a reservoir of a subsurface ice and potential ocean increases the likelihood of a thin atmosphere,exosphere or transient venting existing today. Understanding volatile transport on Ceres will greatly improve our understanding of volatile transport on objects like the Moon, Pluto, and the icy satellites. Measuring any atmosphere on Ceres would also provide constraints on Ceres’ overall volatile content, with implications for Ceres’ history as well as the history of other objects in the main belt. Measurement of D/H in the gas phase, as has been recently done by the Cassini INMS for Enceladus (Waite et al. 2009), would offer the most definitive test of an in situ vs. Kuiper belt origin for Ceres.

Fig. 05: Earth, Moon and Ceres size comparison in near natural colours. While Ceres appears minor in comparison to the Earth, the dwarf planet has a total surface area of 2,770,000 square kilometers or that of Argentina.

Fig. 06: Sunrise over the dwarf planet 1 Ceres centering on the area once known as Bright Spot 5 - Region A. Now officially known as Occator located at Latitude N 19.86 / Longitude E 238.85. In spite of DAWN's arrival at Ceres it is currently uncertain what the bright spots, first made visible in the 2004 Hubble Images, actually are. In my September 2014 illustration above I presented my own scenario of how the dwarf planet 1 Ceres may appear. There have been numerous other white spots since detected and more prominent during daylight periods. They may be a combination of cryovolcanism, sublimation points from impacts and subsequent areas of water ice going through a rapid process of sublimation. In my scenario above I speculated that areas of the northern hemisphere are subject to water ice frost which has a definitive seasonal snowline or better explained as a frostshoreline.

Fig. 07: ESA’s Herschel space observatory has discovered water vapour around Ceres, the first unambiguous detection of water vapour around an object in the asteroid belt. Approximately 6 kg of water vapour is being produced per second from two principal regions. They being from the Piazzi Region banded from pole to pole at 123 degrees Longitude and Region A banded from pole to pole at 240 degrees Longitude.

Fig. 08: Global topographic map of Ceres with names based on Agricultural deities. Here there is great surface clarity when compared to previous imagery captured by either the Keck II and Hubble Space Telescopes. There is approximately a 7.5 km variation from the mean where yellow / green make the transition. The crater basin of Occator lies below the mean and so does Haulani. Indigo represents lowest points and red to white as highest points above the mean therefore the surface variation is approx 15 km.

Fig. 09: While Occator with its prominent bright spots grabs all the attention it is with Haulani which intrigues me most. This oblique and raw image taken by DAWN of the area in the vicinity to the Haulani crater, in near to natural colour, points to some unexplained phenomenon happening right now on or near to the surface of Ceres. The main crater at the centre of this image, Haulani, is approx 30 km in diameter and about 2 km or more deep and is situated close to the equator and at the mean surface altitude. White areas indicate probable ice and or frost present while the lighter browns within the crater its self are possibly claylike soils. It wouldn't be so wild to speculate that the dark areas present may be indeed evidence of carbon based materials laying on the surface after being ejected via some internal cryovolcanic processes. Further more these dark materials may show evidence of a near to surface biosphere - low temperature dwelling psychrophiles upwards to even lichens of some exotic form. Ceres has a tenuous, but oxygen rich atmosphere. Atmospheric "air" pressure may be at approx 0.1519 Mbar (0.015 psi) when below the mean level and increase in even lower laying regions such as both polar regions.     

Fig. 10: Leaping up to 30 m off the surface of Ceres would require the energy on Earth to achieve a jump of approx 1 m. Here a hypothetical 1 Ceres Biosphere (lichen and or carbon / coral / clay structure) in the water vapor and oxygen rich cryovolcanic water ice area of the Haulani crater. Sub-surface aquifers due to the internal heat sources and or the processes of volatiles released from silicate rich hydro / thermal vents may possibly support microbial to macro life forms in or close to convection ice and clay rich soils or even rocks. While there are extremely low temperature (below - 30 degrees celsius on the surface of 1 Ceres) there may however be sub-surface dwelling psychrophiles or at least archaeo - single celled microorganisms. Their habitat may be within convection ice / reg material / antifreeze liquids etc. My hypothetical scene illustrated would be located below the 1 Ceres mean datum level. Here a viable atmosphere may be present allowing such evolved extremophiles to coexist. Although a hypothetical moon of 1 Ceres - Proserpina in 2015 is probably not likely the hypothesis for life on Ceres is still yet to be made evident.

Fig. 11: Two moons rising over the eastern equatorial horizon on 1 Ceres. Over 230 minor planets in our solar system are known to have moons and there are approx 84 in the asteroid belt - with 5 minor planets having two moons. Therefore it may not come as a surprise that 1 Ceres also has at least one natural satellite and certainly quasi satellites like the Earth. If there were to be two moons of 1 Ceres, very small as not to have yet been detected, perhaps they should be named by the International Astronomical Union as Liber and Libera. It was the late Republican era Roman - Cicero who described Liber (male) the guardian of plebeian freedom and Libera (female) goddess of wine, fertility and also freedom, as Ceres' children. In 2015 the term freedom has great significance worldwide in these troubled times - Liber and Libera may make their selves known to us.   

Fig. 12: Since its discovery by Giuseppe Piazzi in 1801 and up to the recent past we are still in the Science Discovery Period 1.0 when concerning the dwarf planet Ceres. However 2015 is the transitory period to the Science Discovery Period 2.0 with the arrival of the DAWN mission. Inevitably will follow other unmanned missions such as robotic Polar Landers and Curiosity type rovers. Human spaceflight to the dwarf planet 1 Ceres may not be until as late the 2050s although my guess is somewhere between 2032 and 2045. Sending humans to Ceres initially could involve trial and tested Luna Lander technology by as early as the 2030s - where: Frank E. Laipert, James M. Longuski, Low-Thrust Trajectories for Human Missions to Ceres, Acta Astronautica, Once the ship has been confired in LEO this proposal for a Low Trust Trajectory would spiral then Earth for up to two years before crew would depart for Ceres in a CTV (crew transfer vehicle). For their study a trajectory from Earth to Ceres that delivers 125 Mg (i.e.metric tons) of mass in 270 days, while minimizing the total departure mass. This 125 Mg includes the propulsion system mass.

In my own conceptual illustration above I have made a scenario for the 1 Ceres - Piloted / Electric Ion Propulsion CTV (min 5 crew transfer vehicle) in its full configuration - without the 1 Ceres trajectory LEO escape rocket booster. This ship would be made up of several segments launched separately for LEO assemblage by up to 3 heavy lift vehicles / 1 crew launch vehicle. The CTV would be up to 46.6m in length (including configured rover / hab - see below). The crew of this ship would travel with the addition of a 1 Ceres gravity twin hab centrifuge - achieved at a 12m radii for comfort and adjustment for a long duration mission of up to 2.5 years round trip. A 30 cm water jacket (cryo and or waste) surrounding both crew habitat areas, hab egress passages, ship's core and command module walls would suffice against solar and cosmic radiation mitigation. Whipple shielding would also be necessary for mitigation against micro meteorite strikes. Electric Ion propulsion, after the 1 Ceres trajectory from Earth is launched, would allow the ship to travel up to 3 km/per second en route to Ceres. There would be required an additional heavy lift vehicle - the STV (supply transfer vehicle) sent to Ceres long before the CTV has set course. It carrying an inflatable surface hab / power source / robotics / airlock and Earth return propellant).


Fig. 13: Establishing scientific stations and depending on wherever Ceres proves to have a biosphere there may required anything starting with an orbital hab to even a geostationary platform with 1 Ceres centrifuge / crew quarters. If Ceres has no detectable biosphere than there may be the use of all terrain mobile habitats. Numerous surface missions could be made with these mobile habs. My scenario (illustrated) for an ATRH - all terrain rover hab / extra-planetary for long duration on the surface of Ceres. Such vehicles may be powered by ASRG (advanced Stirling radioisotope generators). Travel navigation: Stn / sat. interface / data base. Autonomous - 9 wheel ind drive, high torque 3.0 km p/h operational speed with the aid of low power radar and or 3D laser navigation. Atmospheric Stn: vacuum pumps for the extraction of local oxygen / water vapor / Human waste 99.99% recycle. 3 crew - 120 day exploratory vehicle. 3 crew Unit Habs / Airlock Core surface egress to Orbital Stn.

The Case for Ceres: Report to the Planetary Science

Decadal Survey Committee by Andrew Rivkin

Fig. 01 - 04 (Thomas Roatsch) 08 and 09 NASA / JPL  

Illustrations in Fig. 06 and 10 - 13 Copyright by Sean D. 2015

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