Fig. 01: Hubble Space Telescope views of the dwarf planet 1 Ceres. A number of white spots are visible, however as at 2012 it is unclear what they actually reveal other than sites of major impacts from the bombardment period. A little is known about Ceres such as equatorial surface temperatures averaging minus 38 Celsius have been estimated from Earth based observation and that there may be a tenuous atmosphere. It will not be until the arrival of NASA's unmanned DAWN mission in late March 2015 when surface details are better revealed. In August 2015 high altitude 3D mapping commences at 1480 Km and by November 2015 it will descend to as low as 375 Km above the surface.
Fig. 02: 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.
Fig. 03: Intensity scale view of 1 Ceres from the Keck II Telescope on Hawaii showing the same face given in Fig. 01 - center left image. Centered on the area now know as Region A at 240 degrees Longitude. The dwarf planet is of oblate spheroid is shape, has an average polar radius of 454.7 km and an equatorial radius of 487.3 km. Therefore the differences in height are approx 32.6 km from the lowest polar to highest equatorial points. If a mean elevation point is taken then the highest peak would be over 16300 metres.
Below I have copied an excellent document from the web by the Author: Andrew Rivkin
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 timeframe (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 groundbased 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. 04: My illustration of the dwarf planet 1 Ceres based on interpretations from Figs: 01 and 03 and centered on the area now know as Region A at 240 degrees Longitude. The central peak may indeed be a cryovolcanic cone. The white spots visible in the 6 Hubble images in Fig 01 could be exposed ice deposits within deep impact basins penetrating the sub-surface ocean. However these features could also be intermittent orographic cloud formation due to out gassing from low laying and exposed ice deposits. The North Polar region shows signs of frost due to out gassing and / or geothermal activity based on unconfirmed observations made in the early 1990s. More recently there have been confirmed observations of water vapor being emitted from the region shown - known as Region A and from the Piazzi feature located on the other side of the dwarf planet. The water evaporation could be due to comet-like sublimation or to cryo-volcanism. It is likely that Ceres has a tenuous, but oxygen rich atmosphere, from where air pressure would be at approx 0.015 psi in lower laying regions such as at the poles and deep impact basins.
Fig. 05: 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 at 120 degrees Longitude and the area now know as Region A at 240 degrees Longitude.
Fig. 06: The Hypothetical Micro Atmosphere of Ceres. Illustration showing the predominance for the northern hemisphere to have a micro - ionosphere. In this hypothesis the atmospheric pressure would reach up to 0.09 psi at the surface level only a fraction of that of the earth, nonetheless Ceres may be more Earth like than even Mars. In this scenario numerous springs are the primary source for water vapour out gassing and due to this periodic cloud formations may be present. Blue highlight indicates surface frost and near surface ice increasing at the poles and venting sources.
Fig. 07: The surface of the dwarf planet 1 Ceres with view over an impact basin. A decreasing "shoreline" due to exposed water ice being eroded through space weathering would leave interesting geographic features. If geothermal activity exists on Ceres evidence of this may appear in such deep impact basins. Sub-surface aquifers and hydro thermal vents could possibly support microbial life forms in the clay rich soils or at least archaeo - single celled microorganisms. The ascending Lander in the foreground would be at approximately 5 km above the supposed ice sheet which is at a depth of 11 km below the mean Ceres altitude.
Fig. 08: Science Discovery Period 2.0 (my own projections for the period 2015 - 2070s) Since its discovery by Giuseppe Piazzi in 1801 to the present, I would best describe that we are still in the Science Discovery Period 1.0 when concerning the dwarf planet Ceres. However we are nearing the cusp of the Science Discovery Period 2.0 - to literally commences in February 2015 with the arrival of the DAWN mission. Inevitably will follow other unmanned missions such as robotic Polar Landers and Curiosity type rovers. Sending humans to Ceres initially could involve trial and tested Luna Lander technology by as early as the 2030s, but more realistically human space flight to Ceres may not be until as late the 2050s. Above I have illustrated a scenario for the Ceres piloted Electric Ion Propulsion CTV (6 crew transfer vehicle) in its full configuration. This ship would be made up of several segments launched separately by up to 4 heavy lift vehicles for LEO assemblage and be 46.6m in length (including configured rover). The crew of this ship would travel first class with the addition of an optional Ceres gravity twin hab centrifuge - achieved at a 12m radii for comfort and adjustment for a long duration mission of up to 2 years round trip. A 30cm water jacket in the twin habs walls would suffice against solar and cosmic radiation mitigation. Electric Ion propulsion would allow the ship to travel up to 3km per second once in its trajectory. There would be required a STV (supply transfer vehicle - with surface hab) sent to Ceres long before the CTV has set course.
Fig. 09: The establishment of long duration scientific stations, such as the all terrain mobile habitat illustrated, will be required to run the numerous sortie missions into obtaining extensive soil, rock and ice samples. My drawing shows such a scenario for an ATRH - all terrain extra-planetary rover hab for long duration on the surface of Ceres. Such vehicles would require ASRG (advanced stirling radioisotope generators) travel with the aid of low power radar navigation and possibly use atmospheric vacuum pumps for the extraction of local oxygen.
Fig. 10: Eventually a permanent human presence on Ceres would firstly require Macro Terra-formation or Para Terra-formation (World housing). Period 3.0 (beyond 2070). The components for the colonies' main habitats would possibly be a number of linear cities suspended over the primary Para Terra-formed region from where the colonists would inhabit.
As transporting raw materials from Ceres to Mars would be less energy intensive than from the Earth, the dwarf planet makes a valuable resource for inevitable Mars colonization. Macro Terra-formation sites on Ceres would require carbon nano-tube structures to establish and contain an earth-like climate. They would also importantly allow for enclosed cocoon like space for the full protection from the vacuum of space and harm full solar / cosmic rays. Due to the surface gravity on Ceres being only 3% that of the Earth or 0.028 g it would have peculiar effects on hydrostatic equilibrium and plant growth. Construction of Earth gravity centrifuges however would be a remedy for the long term settlers well being. The Ceres Colony would have to become near self-sufficient due to the distances and costs involved into shipping in supplies from the Earth. Human and technological capital would initially be imported. If resource rich the asteroid belt will provide for a growing Ceres colony and or a transfer station for the exportation of goods.
Fig. 11: Once terraformation has been established the low gravity of Ceres would effect the growth of plants and animals on its surface. Bio engineered plants imported from the earth my evolve into a mega flora and would thrive in such an environment where there are poor soils and low light levels. Areas at low altitudes, but close to the equatorial region, geothermal or cryovolcanic regions would also assist in the early stages for global terraformation.
Fig. 12: Global Terra-formation Period 1.0 (2100s and beyond). During the Science Discovery Period 2.0 (2015 - 2070s) it will become clear whether Ceres has, dose or can support life. Establishing a colony on Ceres may be possible, however even for this small world, it would involve an enormous enterprise for the completion of global Terra-formation. Ceres now may have a very tenuous atmosphere of oxygen, however to sustain a breathable earth-like atmosphere would be virtually impossible to achieve unless the dwarf planet is to have firstly established a magnetosphere. If Ceres has a large enough iron core, or any iron for that fact, perhaps an artificial magnetosphere could be created. This project would involve technology still unavailable such as cold fusion. However with the vast sub-surface ocean which Ceres evidently has the most fundamental resource required - water is in abundance. It may even be the future colony's highest trade able commodity for export to a certain Mars colony. How Global Terra-formation would impact or influence any possible indigenous life forms is an important ethical and moral question.
Illustrations in Fig. 04 and 06 - 12 Copyright by Sean D. 2014
The Case for Ceres: Report to the Planetary Science
Decadal Survey Committee by Andrew Rivkin