Hostos School Science Club
You can learn anything!

Publication Award

December 15th, 2016


Publication Announcement

November 24th, 2016

Faculty member of the science department at O y M Hostos Schoo, Dale Albert Johnson Ph.D., ,l has received word of the publication of his peer-reviewed chapter in in scientific publication based in Salzburg, Austria. His research on his discovery of 8th century archaeological evidence  of ethno-religious artifacts in central China during the Tang Dynasty adds evidence to a previously unknown presence of Middle Eastern immigrants in Central China.


As early as AD 781, the writer of the Xi’an Fu inscription described the spread of Syriac Christianity (called Jingjiao in Chinese) to China as a wind blowing eastward. The discovery of the Xi’an Fu Stele, the Dunhuang Jingjiao Manuscripts, the numerous Syriac tombstones and fragments in Central Asia and many parts of China has unearthed a buried history of Syriac Christianity from the Tang Dynasty to the time of the Mongol Empire. The papers in this volume cover a wide range of topics from manuscripts and inscription, to the historical, liturgical and theological perspectives of Syriac Christianity in this geographic realm. Li Tang is Senior Research Fellow at the Department of Biblical Studies and Ecclesiastical History, University of Salzburg.. Dietmar W. Winkler is Professor of Patristic Studies and Ecclesiastical History at the University of Salzburg and Director of the Center for the Study of Eastern Christianity (ZECO) of the University of Salzburg. (Series: Orientalia – Patristica – Oecumenica, Vol. 9) [Subject: Religious Studies, History, Syriac Christianity, Chinese Studies]


Lab Study of Surface Tension

November 24th, 2016


Science Reports

November 17th, 2016

Surface Tension

Calculator for water tension

List of equations in fluid mechanic
Here is a unit vector in the direction of the flow/current/flux.
Quantity (common name/s) (Common) symbol/s Defining equation SI units Dimension
Flow velocityvector field
m s−1 [L][T]−1
s−1 [T]−1
Volume velocity, volume flux φV (no standard symbol)
m3 s−1 [L]3 [T]−1
Mass current per unit volume
s (no standard symbol)
kg m−3 s−1 [M] [L]−3 [T]−1
Mass current, mass flow rate
kg s−1 [M][T]−1
Mass current density jm
kg m−2 s−1 [M][L]−2[T]−1
Momentum current Ip
kg m s−2 [M][L][T]−2
Momentum current density jp
kg m s−2 [M][L][T]−2
Physical situation Nomenclature Equations
Fluid statics,
pressure gradient
• r = Position
• ρ = ρ(r) = Fluid density at gravitational equipotential containing r
• g = g(r) = Gravitational field strength at point r
• ∇P = Pressure gradient

Buoyancy equations • ρf = Mass density of the fluid
• Vimm = Immersed volume of body in fluid
• Fb = Buoyant force
• Fg = Gravitational force
• Wapp = Apparent weight of immersed body
• W = Actual weight of immersed body Buoyant force

Apparent weight

Bernoulli’s equation
pconstant is the total pressure at a point on a streamline

Euler equations
• ρ = fluid mass density
• u is the flow velocity vector
• E = total volume energy density
• U = internal energy per unit mass of fluid
• p = pressure
• denotes the tensor product

Convective acceleration

Navier–Stokes equations
• TD = Deviatoric stress tensor
• = volume density of the body forces acting on the fluid
• here is the del operator.

Some typical liquid propertiesWaterIdeal gas lawKinetic theory

This principle is stated mathematically as:

{\displaystyle \Delta P=\rho g(\Delta h)\,} \Delta P=\rho g(\Delta h)\,
{\displaystyle \Delta P} \Delta P is the hydrostatic pressure (given in pascals in the SI system), or the difference in pressure at two points within a fluid column, due to the weight of the fluid;
ρ is the fluid density (in kilograms per cubic meter in the SI system);
g is acceleration due to gravity (normally using the sea level acceleration due to Earth’s gravity, in SI in metres per second squared);
{\displaystyle \Delta h} \Delta h is the height of fluid above the point of measurement, or the difference in elevation between the two points within the fluid column (in metres in SI).

The hydrodynamics of water strider locomotion David L. Hu1 , Brian Chan2 & John W. M. Bush1 1 Department of Mathematics, and 2 Department of Mechanical Engineering MIT, Cambridge, Massachusetts 02139, USA
……………………………………………………………………………………………………………………………………………………….. Water striders Gerridae are insects of characteristic length 1 cm and weight 10 dynes that reside on the surface of ponds, rivers, and the open ocean1–4. Their weight is supported by the surface tension force generated by curvature of the free surface5,6, and they propel themselves by driving their central pair of hydrophobic legs in a sculling motion7,8. Previous investigators have assumed that the hydrodynamic propulsion of the water strider relies on momentum transfer by surface waves1,9,10. This assumption leads to Denny’s paradox11: infant water striders, whose legs are too slow to generate waves, should be incapable of propelling themselves along the surface. We here resolve this paradox through reporting the results of high-speed video and particletracking studies. Experiments reveal that the strider transfers momentum to the underlying fluid not primarily through capillary waves, but rather through hemispherical vortices shed by its driving legs. This insight guided us in constructing a self-contained mechanical water strider whose means of propulsion is analogous to that of its natural counterpart. Whereas substantial advances have been made in the field of biolocomotion9,12–16, the hydrodynamics underlying the surface locomotion of semiaquatic insects remains poorly understood1,9,11,17. There are two means of walking on water according to the relative magnitudes of the body weight Mg and the maximum curvature force jP, where M is the body mass, g the gravitational acceleration, j the surface tension and P the contact perimeter of the water-walker17. Water-walkers characterized by Mc ¼ Mg jP . 1, such as the basilisk lizard, rely on the force generated by their feet slapping the surface and propelling water downward18. Creatures with Mc , 1, such as the water strider may reside at rest on the surface, supported by the curvature force generated by distortion of the free surface (Fig. 1). The body and legs of the water strider are covered by thousands of hairs1 that render its legs effectively nonwetting19. During their rowing stroke, water striders drive their middle legs against the water without penetrating the surface and may achieve peak speeds of 150 cm s21 . The striders may launch themselves with a vertical component, or glide along the surface. The force balance on a stationary water strider may be understood in terms of the statics of floating, non-wetting bodies6 . The weight of a stationary water strider is supported by some combination of the buoyancy force, Fb, and the curvature force, Fc, associated with the surface tension j : Mg ¼ Fb þ Fc. Fb is deduced by integrating the hydrostatic pressure over the body area in contact with the water, while Fc is deduced by integrating the curvature pressure over this area, or equivalently the vertical component of the surface tension, jsinv, along the contact perimeter (Fig. 1b). Keller6 demonstrated that the ratio of Fb to Fc is equal to that of the fluid volumes displaced inside and outside the contact line. For a long thin water-strider leg, this ratio is Fb/Fc , w/Lc ,, 1, where w < 40 mm is the leg radius1 , Lc ¼ ðj=rgÞ 1=2 < 2 mm the capillary length, and r the density of water. The strider’s weight is supported almost exclusively by surface tension. Figure 2 illustrates the dependence of the maximum surface tension force on body weight for 342 species of water striders. The observed dependence illustrates that as the striders increase in size, their legs become proportionately longer. It is only thus that the largest water strider (marked C in Fig. 2), Gigantometra gigas20, whose length may exceed 20 cm, is a viable water-walker. For the water strider to move, Newton’s third law requires that it transfer momentum to the underlying fluid. It has previously been assumed that capillary waves are the sole means by which to accomplish this momentum transfer1,9–11. Denny9 suggested that the leg speed of the infant water strider is less than the minimum phase speed of surface waves21, cm ¼ ð4gj=rÞ 1=4 < 23:2 cm s21; consequently, the infants are incapable of generating waves and so transferring momentum to the underlying fluid. According to this physical picture, infant water striders cannot swim, an inference referred to as Denny’s paradox9,11. A series of laboratory experiments were conducted in order to elucidate the hydrodynamic propulsion mechanism of the water strider Gerris remigis. Water striders were collected from local freshwater ponds and maintained in aquaria. The striders reproduced every several weeks, providing the opportunity to study the first-instar nymph water striders in a laboratory setting. The striders were filmed using a high-speed video camera at 500 frames per second and the images were digitized and analysed using Midas motion analysis software. Particle tracking was performed by seeding water with either Kalliroscope or Pliolite particles of size 50–100 mm. Dye studies were performed using food colouring and thymol blue. Images of the waves and vortices generated by the strider motion were obtained from both plan and side views; their form and speed were measured directly following the stroke. The surface signature of the capillary waves was measured with a technique adopted from Schooley22. The Reynolds number characterizing the adult leg stroke is Re ¼ UL2=n < 103; where U < 100 cm s21 is the peak leg speed and L2 < 0.3 cm is the length of the rowing leg’s tarsal segment (see Figs 1b and 2), which prescribes the size of the dynamic meniscus forced by the leg stroke23. For the 0.01-s duration of the stroke, the driving legs apply a total force F < 50 dynes, the magnitude of letters to nature NATURE | VOL 424 | 7 AUGUST 2003 | © 2003 Nature PublishingGroup 663 Figure 1 Natural and mechanical water striders. a, An adult water strider Gerris remigis. b, The static strider on the free surface, distortion of which generates the curvature force per unit leg length 2j sin v that supports the strider’s weight. c, An adult water strider facing its mechanical counterpart. Robostrider is 9 cm long, weighs 0.35 g, and has proportions consistent with those of its natural counterpart. Its legs, composed of 0.2-mm gauge stainless steel wire, are hydrophobic and its body was fashioned from lightweight aluminium. Robostrider is powered by an elastic thread (spring constant 310 dynes cm21 ) running the length of its body and coupled to its driving legs through a pulley. The resulting force per unit length along the driving legs is 55 dynes cm21 . Scale bars, 1 cm. Figure 2 The relation between maximum curvature force Fs ¼ jP and body weight Fg ¼ Mg for 342 species of water striders. j is the surface tension of either pond water (67 dynes cm21 ) or sea water17 (78 dynes cm21 ) at 14 8C and P ¼ 4(L1 þ L2 þ L3) is twice the combined lengths of the tarsal segments (see strider B). Anatomical measurements were compiled from existing data20,26–29. Open symbols denote striders observed in our laboratory. Insets show the adult Gerris remigis (B) and extremes in size: the first-instar infant Gerris remigis (A) and the Gigantometra gigas20 (C). The solid line represents Mc ¼ 1, the minimum requirement for static stability on the surface. The surface tension force is more than adequate to support the water strider’s weight; however, the margin of safety (the distance above Mc ¼ 1) decreases with increasing body size. If the proportions of the water strider were independent of its characteristic size L, one would expect P , L and hence Fs , L, and Fg , L 3 : isometry would thus suggest Fs , F g 1/3, a relation indicated by the dash-dotted line. The best fit to the data is given by Fs ¼ 48F g 0.58 (dashed line). Characteristic error bars are shown. letters to nature 664 © 2003 Nature PublishingGroup NATURE | VOL 424 | 7 AUGUST 2003 | which was deduced independently by measuring the strider’s acceleration and leaping height. The applied force per unit length along its driving legs is thus approximately 50/0.6 < 80 dynes cm21 . An applied force per unit length in excess of 2j < 140 dynes cm21 will result in the strider penetrating the free surface. The water strider is thus ideally tuned to life at the water surface: it applies as great a force as possible without jeopardizing its status as a water-walker. The propulsion of a one-day-old first-instar is detailed in Fig. 3. Particle tracking reveals that the infant strider transfers momentum to the fluid through dipolar vortices shed by its rowing motion. The wake of the adult water strider is similarly marked by distinct vortex dipole pairs that translate backwards at a characteristic speed Vv < 4 cm s21 (Figs 3c and 4). Video images captured from a side view indicate that the dipolar vortices are roughly hemispherical, with a characteristic radius R < 0.4 cm. The vertical extent of the hemispherical vortices greatly exceeds the static meniscus depth24, 120 mm, but is comparable to the maximum penetration depth of the meniscus adjoining the driving leg, 0.1 cm. A strider of mass M < 0.01 g achieves a characteristic speed V < 100 cm s21 and so has a momentum P ¼ MV < 1 g cm s21 . The total momentum in the pair of dipolar vortices of mass Mv ¼ 2pR3 /3 is Pv ¼ 2MvVv < 1 g cm s21, and so comparable to that of the strider. The leg stroke may also produce a capillary wave packet, whose contribution to the momentum transfer may be calculated. We consider linear monochromatic deep-water capillary waves with surface deflection z(x,t) ¼ aei(kx2qt) propagating in the x-direction with a group speed c g ¼ dq/dk, phase speed c ¼ q/k, amplitude a, wavelength l ¼ 2p/k and lateral extent W. The time-averaged horizontal momentum associated with a single wavelength, Pw ¼ pjka2Wc21, may be computed from the velocity field and relations between wave kinetic energy and momentum21,25. Our measurements indicate that the leg stroke typically generates a wave train consisting of three waves with characteristic wavelength l < 1 cm, phase speed c < 30 cm s21 , amplitude a < 0.01– 0.05 cm, and width L2 < 0.3 cm (see Fig. 3c). The net momentum carried by the capillary wave packet thus has a maximum value Pw < 0.05 g cm s21 , an order of magnitude less than the momentum of the strider. The momentum transported by vortices in the wake of the water strider is comparable to that of the strider, and greatly in excess of that transported in the capillary wave field; moreover, the striders are capable of propelling themselves without generating discernible capillary waves. We thus conclude that capillary waves do not play an essential role in the propulsion ofGerridae, and thereby circumvent Denny’s paradox. The strider generates its thrust by rowing, using its legs as oars and its menisci as blades. As in the case of rowing boats, while waves are an inevitable consequence of the rowing action, they do not play a significant role in the momentum transfer necessary for propulsion. We note that their mode of propulsion relies on the Reynolds number exceeding a critical value of approximately 100, suggesting a bound on the minimum size of water striders. Our continuing studies of water strider dynamics will follow those of birds, insects and fish11,15,16 in characterizing the hydrodynamic forces acting on the body through detailed examination of the flows generated during the propulsive stroke. We designed a mechanical water strider, Robostrider, constructed to mimic the motion of a water strider (Fig. 1c). Its proportions and Mc value were consistent with those of its natural counterpart Figure 3 The flow generated by the driving stroke of the water strider. a, b, The stroke of a one-day-old first-instar water strider. Sequential images were taken 0.016 s apart. a, Side view. Note the weak capillary waves evident in its wake. b, Plan view. The underlying flow is rendered visible by suspended particles. For the lowermost image, fifteen photographs taken 0.002 s apart were superimposed. Note the vortical motion in the wake; the flow direction is indicated. The strider legs are cocked for the next stroke. Scale bars, 1 mm. c, A schematic illustration of the flow structures generated by the driving stroke: capillary waves and subsurface hemispherical vortices. letters to nature NATURE | VOL 424 | 7 AUGUST 2003 | © 2003 Nature PublishingGroup 665 (Fig. 2). The challenge was constructing a self-contained device sufficiently light to be supported by surface tension and capable of rowing without breaking the water surface. An important design criterion, that the force per unit length along the driving legs not exceed 2j, was met by appropriate choice of elastic thread and pulley. High-speed video footage indicates that Robostrider does not break the surface despite leg speeds of 18 cm s21 . Like its natural counterpart, the Robostrider generates both capillary waves and vortices, and the principal momentum transfer is in the form of vortices shed by the rowing motion. Robostrider travels half a body length per stroke in a style less elegant than its natural counterpart. A Received 8 February; accepted 6 May 2003; doi:10.1038/nature01793. 1. Andersen, N. M. A comparative study of locomotion on the water surface in semiaquatic bugs (Insecta, Hemiptera, Gerromorpha). Vidensk. Meddr. Dansk. Naturh. Foren. 139, 337–396 (1976). 2. Brinkhurst, R. O. Studies on the functional morphology of Gerris najas degeer (Hem. Het. Gerridae). Proc. Zool. Soc. Lond. 133, 531–559 (1960). 3. Murphey, R. K. A: Motor control of orientation to prey by the water strider Gerris remigis. Z. Vergl. Physiol. 72, 150–167 (1971). 4. Wilcox, R. S. Sex discrimination in Gerris remigis: Role of a surface wave signal. Science 206, 1325–1327 (1979). 5. Baudoin, R. La physico-chimie des surfaces dans la vie des arthropodes aeriens des miroirs d’eau, des rivages marins et lacustres et de la zone intercotidale. Bull. Biol. Fr. Belg. 89, 16–164 (1955). 6. Keller, J. B. Surface tension force on a partly submerged body. Phys. Fluids 10, 3009–3010 (1998). 7. Darnhofer-Demar, B. Zur Fortbewegung des Wasserlaufers Gerris lacustris L. auf des Wasseroberflache. Zool. Anz. Suppl. 32, 430–439 (1969). 8. Bowdan, E. Walking and rowing in the water strider, Gerris remigis. J. Comp. Physiol. 123, 43–49 (1978). 9. Denny, M. W. Air and Water: The Biology and Physics of Life’s Media (Princeton Univ. Press, Princeton, NJ, 1993). 10. Sun, S. M. & Keller, J. B. Capillary-gravity wave drag. Phys. Fluids 13, 2146–2151 (2001). 11. Suter, R. B., Rosenberg, O., Loeb, S., Wildman, H. & Long, J. H. Locomotion on the water surface: propulsive mechanisms of the fisher spider Dolomedes triton. J. Exp. Biol. 200, 2523–2538 (1997). 12. Childress, S. Mechanics of Swimming and Flying (Cambridge Univ. Press, Cambridge, UK, 1981). 13. Vogel, S. Life’s Devices (Princeton Univ. Press, Princeton, NJ, 1988). 14. Dickinson, M. H. et al. How animals move: an integrated view. Science 288, 100–106 (2000). 15. Rayner, J. M. V., Jones, G. & Thomas, A. Vortex flow visualizations reveal change in upstroke function with flight speed in bats. Nature 321, 162–164 (1986). 16. Ellington, C. P. Oxygen consumption of bumblebees in forward flight. Nature 347, 472–473 (1990). 17. Vogel, S. Life in Moving Fluids (Princeton Univ. Press, Princeton, NJ, 1994). 18. Glasheen, J. W. & McMahon, T. A. A hydrodynamic model of locomotion in the Basilisk Lizard. Nature 380, 340–342 (1996). 19. de Gennes, P.-G., Brochard-Wyart, F. & Quere, D. Gouttes, Boules, Perles et Ondes (Belin, Collection Echelles, Paris, 2002). 20. Tseng, M. & Rowe, L. Sexual dimorphism and allometry in the giant water strider Gigantometra gigas. Can. J. Zool. 77, 923–929 (1999). 21. Lamb, H. Hydrodynamics, 6th edn (Cambridge Univ. Press, Cambridge, 1932). 22. Schooley, A. H. Profiles of wind-created water waves in the capillary-gravity transition region. J. Mar. Res. 16, 100–108 (1958). 23. Suter, R. B. & Wildman, H. Locomotion on the water surface: hydrodynamic constraints on rowing velocity require a gait change. J. Exp. Biol. 202, 2771–2785 (1999). 24. Matsuda, K., Watanabe, S. & Eiju, T. Real-time measurement of large liquid surface deformation using a holographic shearing interferometer. Appl. Opt. 24, 4443–4447 (1985). 25. Starr, V. P. Momentum and energy integrals for gravity waves of finite height. J. Mar. Res. 6, 175–193 (1947). 26. Andersen, N. M. The Semiaquatic Bugs (Hemiptera, Gerromorpha): Phylogeny, Adaptations, Biogeography and Classification (Scandinavian Science, Klampenborg, 1982). 27. Hungerford, H. B. & Matsuda, R. Keys to subfamilies, tribes, genera and subgenera of the Gerridae of the world. Kans. Univ. Sci. Bull. 41 (1960). 28. Henry, T. J. & Froeschner, R. C. (eds) Catalog of the Heteroptera, of True Bugs, of Canada and the Continental United States (E. J. Brill, Leiden, 1998). 29. Cobben, R. H. The Hemiptera of the Netherlands. Stud. Fauna Curacao Caribb. Islands 11, 1–34 (1960). 30. Scriven, L. E. & Sternling, C. V. The Marangoni effects. Nature 187, 186–188 (1970). Acknowledgements We thank A. Chau for preparing Fig. 2, M. Hancock, M. Shelley and R. Rosales for discussions, and MIT’s Edgerton Center for lending us their high-speed video equipment. J.W.M.B. gratefully acknowledges the financial support of the NSF. Competing interests statement The authors declare that they have no competing financial interests. Correspondence and requests for materials should be addressed to J.B. (
Plagiarism Contract
I understand that Plagiarism is the act of submitting a paper that, in part or whole, includes the work of another person – work that I did not write. This includes, but is not limited to, copying words from another source without indicating in some manner, i.e. footnotes, quotation marks, or some other means of reference, that these words or ideas come from a source other than myself. Plagiarism also includes receiving assistance with ideas or language (beyond proofreading) from another person outside of this class. In my attached paper, I have taken care to indicate through the use of quotation marks, footnotes, or some other means, words that were taken from another source. In signing below, I am stating that my attached paper is NOT in any way plagiarized, in part or in its entirety. I understand that if I do submit a plagiarized paper I will receive an “F” on the assignment and may be dropped from O and M Physics course.
SIGNATURE _________________________________________ PRINTED NAME______________________________________

Science Club Explores Local Volcano

September 18th, 2016




isabela thomas

The Science Club of O and M Hostos School explored a local volcano September 17, 2016 on Saturday. The team investigated a lava tube and calcium tuffts marking evidence of vulcanism during the early formation of the island 60 million years ago. Rock samples were collected for the NASA program in which the club is participating.


Mars on Earth: soil analogues for future Mars missions

September 8th, 2016

Mars on Earth: soil analogues for future Mars missions

  1. Jeffrey J Marlow,
  2. Zita Martins and
  3. Mark A Sephton

+ Author Affiliations

  1. (

  2. Department of Earth Science and Engineering, South Kensington Campus, Imperial College London, London SW7 2AZ, UK.


Preparations for missions to Mars are a major concern for scientists. Predicting how equipment and experiments will perform on the planet is difficult because tests are restricted to Earth. Mars soil analogues are being used to solve this problem. These terrestrial materials are chemically and physically similar to martian soils and, because they contain unusual minerals and trace amounts of organic matter, are scientifically interesting in their own right. However, no current analogue is appropriate for all necessary tests. Here we describe Mars soil analogues, identify limitations and suggest the need for new Mars simulants.

Mars has long fascinated humankind because of its potential as a host for alien life (Lowell 1909, Klein 1979, Bada 2005). Most of our accumulated knowledge of Mars comes from ground and space-based observations (Bell 1997, Parker 1999, Bell and Ansty 2007, Poulet 2007), martian meteorites such as Nakhla and Allan Hills (ALH) 84001 (Watson 1994, Grady 1995, McKay 1996, Bada 1998, Jull 1998, Becker 1999, Glavin 1999, Bouvier 2005) and spacecraft landers (Jones 1979, Golombek 1999, Squyres 2004). Reaching and landing safely on the Red Planet has proven to be a challenging task despite the success of recent missions (e.g. the Mars Exploration Rovers, figure 1; Crisp 2003). All space missions are time-consuming and expensive and as we look forward to continued exploration of our planetary neighbour it is of the utmost importance that all technical components and experimental procedures for Mars missions function properly once in situ.


Part of the rover Opportunity can be seen in this panoramic view compiled from images taken October-December 2007. The main body of Victoria Crater appears in the upper right. (NASA/JPL-Caltech/Cornell University)

In order to test rover instrumentation before mission launch and improve the chances of success, experimental analyses of terrestrial soils similar to those that will be encountered on the Red Planet have become crucial (Cabrol 2001, Sarrazin 2007). Mars soil analogues provide a preview of the physical environment that a mission to the Red Planet may encounter. They simulate both the type of soils a rover will drive over and the materials that on-board instruments will sample. Mars soil analogues also help to mimic and predict the materials in which trace levels of organic molecules (and possibly life) might be found, particularly in light of recent findings that certain minerals appear to preserve organics better than others under simulated martian conditions (Peeters 2008). Here we describe several Mars soil analogues being used to help planetary scientists prepare for in situ investigations on Mars.

Not just a Red Planet

Mars, like Earth, is a geologically diverse object and the traditional view of it as an exclusively basaltic sandbox is becoming ever more refined, as evidenced by recent discoveries of varied mineralogies at regional and local scales (figure 2). The OMEGA hyperspectral imager on Mars Express identified layered deposits exhibiting high levels of kieserite, gypsum and polyhydrated sulphates at multiple sites in Valles Marineris, Margaritifer Sinus and Terra Meridiani (Gendrin 2005). On a smaller scale, the Spirit rover has found evidence for six different soil types in Gusev Crater and the Columbia Hills, suggesting a range of formation conditions and alteration mechanisms (Morris 2006). Because of this heterogeneity, it is important to establish which part of Mars one is hoping to simulate and then to identify suitable soil analogue candidates that will benefit preparations for successful space missions. For example, a spectrometer prototype for a mission to the gypsum-rich dunes of Olympia Planitia (Langevin 2005) would require a different chemical analogue than a similar mission targeting the basaltic sands of Chyrse Planitia (Greeley 1977). Likewise, a landing systems engineer would seek a different physical analogue for a polar mission depending on whether the mission would land on hardened winter ground or softer summer soils. The robotic armada currently orbiting Mars gives us the ability to identify bulk characteristics of proposed mission targets; using this knowledge to specify and use a suitable analogue on Earth will serve to prepare mission planners better for both the physical and scientific ground to be covered.


Four renderings of spectral data acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter show local variation just south of the Mawrth Vallis region. The true- and false-colour images reveal significant differences that represent variation in mineralogy. CRISM also exposes iron-rich and aluminium-rich clays that correlate to particular rock layers formed under distinct environmental conditions. Similar localized heterogeneity likely occurs across Mars. (NASA/JPL/JHUAPL/Brown University)

Types of Mars analogues

Analogue soils can be classified by the properties of Mars they best mimic, allowing mission planners with specific engineering-based aims to target particular analogues by their properties of interest. These analogues can also be used in a predictive manner to anticipate scientific findings at the destination. For example, understanding the development of a chemically analogous soil on Earth allows us to hypothesize how similar geological processes may occur on Mars. Knowing the concentrations and sources of biological molecules in an analogue soil informs our expectations of the search for past or present life on Mars. Useful analogue classes include the following:

  • Chemical analogues. These include terrestrial soils that are as similar as possible to martian regolith in terms of chemical properties such as dielectric constant, redox potential, pH, elemental composition, and mineralogical composition. This class of analogue is useful for testing and calibrating spectrometers as well as testing procedures that aim to interpret conditions of soil formation on Mars.

  • Mechanical analogues. This class is represented by soils and sites that exhibit similar mechanical properties of the martian regolith, such as soil bearing strength, cohesive strength, and the angle of internal friction. These materials are helpful for input to overall rover design and landing systems, which can also be tested and improved using mechanical analogues.

  • Physical analogues. These soils comprise materials that are Mars-like in their physical properties, such as particle size distribution, particle shape, density, bulk density, porosity, water content, and thermophysical properties (e.g. albedo and thermal inertia). Physical analogues allow us to evaluate the physical effect of martian soil on mechanical components such as spacesuit joints, robotic hinges, and soil intake machinery. Laboratory use of these materials could also help clarify past and present interactions between water and the soil.

  • Magnetic analogues. These are materials with Mars-like magnetic properties including magnetic susceptibility and saturation magnetization. These soils are particularly valuable in testing magnetism-related instruments.

  • Organic analogues. Near-barren soils are specifically useful in simulating the low-organic content of martian soils. The search for signs of past and/or present life on Mars is one of the most important goals for Mars exploration, and several life-detection instruments will be part of upcoming Mars missions (Cabane 2004, Mattingly 2004, Bada 2007). Testing proposed instruments for detection of trace amounts of molecules of biological interest allows scientists and engineers to evaluate instrument sensitivity and functionality in a field environment.

Mars-like terrestrial locations

The value of Mars analogues has long been appreciated, and the scientific and engineering communities have trodden well-worn paths to several sites in the quest for a “Mars on Earth” regolith. Descriptions of selected analogues and their locations follow:

  • Hawaii. Hawaii and Mars both exhibit a history of volcanism, and the near-continuous eruptions of Kalauea Volcano provide the opportunity for real-time study of lava formation and alteration (Farr 2004). The volcanic deposits of the Ka’u Desert, Kilauea, Mauna Loa and Mauna Kea provide a range of useful chemical analogues. Spectral signatures of the basaltic material show significant similarities to high albedo regions on Mars (Singer 1982). Weathered ash from the Pu’u Nene cinder cone on Hawaii is the source for JSC Mars-1, a martian soil simulant collected and characterized by scientists and engineers at Johnson Space Center in 1993 (Allen 1998a, b, Perko 2006). The study of Hawaiian geology and martian climate led some researchers to predict the presence of kaolinite on Mars (Ming 1988), a forecast that has recently been shown to be true (Ehlmann 2007).

  • Salten Skov. The red-coloured sediments of Salten Skov in central Denmark contain high concentrations of iron oxides, especially hematite, maghemite and goethite (Nornberg 2004). Samples from this site are useful both as a magnetic analogue and a chemical analogue for biological applications. Bacterial concentrations in this soil are too high to test life-detection instruments properly, but because of their analogous mineralogical properties, Salten Skov soils can be used to examine the breakdown of cellular components under simulated martian conditions (Hansen 2005). Research has shown that amino acids and other organic molecules present in this soil are degraded under simulated martian conditions due to the oxidizing nature of the material, as is hypothesized to take place on Mars (Garry 2006). Understanding the mechanism of organic molecule destruction will inform the search for signs of past or present life on Mars and allow for more accurate interpretation of future findings.

  • Atacama Desert. The recently heightened pace of the search for past or present life on Mars has led to the identification of an organic analogue soil — a material that contains organic molecules in trace quantities as expected on Mars. Given the tenacity of extremophilic organisms, this has not been an easy task, but researchers have recently proposed the Atacama Desert — the driest place on Earth — as a suitably “sterile” environment. Studies of the regional soil chemistry (Sutter 2005, Ewing 2006) suggest that highly oxidizing conditions, possibly resulting from elevated nitrate levels and the dry-deposition of acids, likely account for the low organic content (Navarro-Gonzalez 2003, Quinn 2005, Lester 2007). Recently, scientists developing life-detection instruments have used this arid region almost exclusively as an organic Mars soil analogue (Buch 2006, Amashukeli 2007, Meunier 2007, Skelley 2007).

  • Mojave Desert. The Mojave Desert of eastern California (figure 3a) exhibits a history of volcanism and tectonic activity, making it a suitable analogue to the highlands of Mars (Howard and Matsubara 2007). Subsequent weathering has produced physical conditions and chemical compositions similar to those on Mars (Beegle 2007). However, the region is used principally as the mechanical analogue of choice and de facto testing ground of Mars landing systems and rovers (Volpe 1999, Behar 2004, Johnson 2005). This area is logistically attractive due to its proximity to the Jet Propulsion Laboratory, where many NASA landers are built, a convenience that minimizes transportation costs and overall risks. The recent production of the Mojave martian simulant from crushed granular basalt aims to overcome some weaknesses of the JSC Mars-1 soil, namely its hygroscopic properties and large volatile composition (Beegle 2007).

  • Arequipa. This high desert site in Southern Peru serves as a chemical and organic martian analogue because of its sulphate mineralogy and a low organic content on a par with Atacama samples. Geochemical parameters such as pH and redox vary over metre-length scales. Recent studies have shown significant rates of amino acid destruction in Arequipa soils under Mars-like conditions, an observation attributed to soil mineralogy that can produce highly oxidizing conditions (Peeters 2008). Similar reactions on Mars may account for Viking’s inability to detect organic molecules (Biemann 1977). Continued study of these soils may demonstrate how organic molecules, from either biological or meteoritic sources, react and persist on Mars.

  • Rio Tinto. The analogues highlighted above have traditionally been used to simulate a homogenized “bulk Mars”, irrespective of the local anomalies a given mission may target. Recent use of the Rio Tinto region in southwestern Spain, however, represents a new step in the evolution of Mars analogue studies, namely the use of a site on Earth that is targeted because of its Mars-like inorganic geochemistry (figure 3b). The Rio Tinto is a red-coloured river with a pH approaching 1 and a thriving microbial community (Gonzalez-Toril 2003). It is a poor match for martian physical or mechanical properties, but the acid-sulphate chemistry provides a helpful model for the development of certain minerals in martian soil observed by Opportunity such as jarosite and hematite (Fernandez-Remolar 2004, Klingelhofer 2004). Working at Rio Tinto allows engineers to fine tune mineralogy-based instruments (Sarrazin 2007) and gives scientists a context in which to interpret rover data.


“Mars Hill” in the Mojave Desert, where multiple rover prototypes have been tested.


Acid-sulphate chemical processes at the Rio Tinto produce minerals such as jarosite and gypsum which are also seen on Mars. This site is being used as a process analogue for soils studied at Meridiani Planum. (Washington University Pathfinder Program)


Meteorites can serve as analogues to determine how organic molecules respond to conditions on Mars in two different capacities: the direct study of martian meteorites, and the investigation of carbonaceous chondrite meteorites under simulated martian conditions.

In the absence of the products of a sample return mission to the Red Planet, the 34 currently known Mars meteorites ( represent the only actual pieces of Mars on Earth. Despite original claims of fossil-like content in the best-known of these meteorites, ALH84001 (McKay 1996), no martian biological molecules were found (Anders 1996, Treiman 2001, Golden 2006). Nonetheless, the search for native organic molecules in martian meteorites continues (Bada 1998, Sephton 2002, Glavin 1999, 2005) and, if found, such molecules would play a significant role in directing future missions.

Exposing carbonaceous meteorites with previously established amino acid contents to martian conditions can also help inform the search for organic molecules on Mars. Meteorites represent a near-certain source of organic molecules on Mars, but their ability to persist on the surface remains unresolved. Exposing carbonaceous meteorites with previously established amino acid contents to martian conditions can also help constrain the search for organics. The Orgueil meteorite, for example, is known to have a simple amino acid distribution, with glycine and b-alanine present in the largest amounts (Ehrenfreund 2001). When placed in a simulated martian environment, Orgueil amino acids deteriorated more quickly than those hosted in the Salten Skov Mars analogue soil. This discrepancy is attributed to mineralogical differences: the clay-rich sediments of Salten Skov appear to slow the radical-induced destruction of amino acids better than the Orgueil meteorite (Peeters 2008). The use of meteorites in this comparative capacity helps point to mineralogical hotspots on Mars that should be targeted by future life-detection missions.

Towards a comprehensive catalogue

Analysis of Mars soil analogues is a crucial part of our preparations for exploration of the Red Planet, offering a relatively cheap and safe opportunity to test mission hardware and study potentially Mars-like scientific processes. Yet, despite the interdisciplinary importance of high-fidelity Mars soil analogues, centralized data on soil parameters and analogue uses are in short supply and are inconsistently acquired. Mineralogical information, for example, can be acquired by several different analytical methods including thermal emission spectroscopy, X-ray diffraction, Mossbauer spectroscopy, or alpha particle X-ray spectroscopy. Data obtained decades ago may be obsolete given the technological advancements of analytical instruments in the intervening years. One of the current analogues of choice, JSC Mars-1, was enthroned largely due to spectral data available in the early 1990s. This basis for comparison is elementary by modern standards; incorporating findings from contemporary rovers and hyperspectral orbiters could point to more promising analogues. Even when multiple types of information for a site are available, they often come from studies examining different locations at different times with different instruments. Disparate studies ostensibly sampling the same location could very well be separated by hundreds of miles, dozens of years, several inches of rainfall, etc; in such cases, it is impossible to account for all confounding variables.

The Mars exploration community requires chemical, mechanical, physical, magnetic and organic data, but not all of these parameters are available for each sample. Table 1 highlights this issue — it lists all soil properties that have been measured on Mars over the last three decades and shows how our knowledge of soil analogue sites compares. An entry indicates the presence of accessible data, while a blank cell indicates the absence of certain information for the corresponding analogue. As demonstrated in table 1, there are many gaps in our inventory of available data. Most notably, field work often fails to survey and/or communicate macroscopic and thermophysical properties. Subjecting analogue soils to a wider range of spectroscopic surveys, particularly those using techniques with a history of operation on Mars (e.g. Mossbauer) would allow scientists and engineers to better cross-reference data from multiple instruments and make more informed inferences about martian destinations. Our summary is a useful starting point, but Mars mission planners and scientists would profit greatly from the ability to access a comprehensive data set of soil analogue properties.


Mars analogue soils


Missions to Mars are too expensive and infrequent and the potential scientific return is too great to leave something to chance. Maintaining a comprehensive and reliable database of soil analogue properties would allow researchers to target specific sites best tailored to their individual requirements. By using soil analogues to their full potential, our continued exploration of Mars can be safer and more scientifically productive.

Acknowledgments and references

The authors are grateful for financial support from the Marshall Scholarships Programme and the Science and Technology Facilities Council (STFC).


  • Exploring Mars would be easier if researchers knew more about the properties and behaviour of martian soils. Jeffrey J Marlow, Zita Martins and Mark A Sephton explain how terrestrial analogues could help — especially if we had more of them.


Sample Rocks from DR for Mars study

September 8th, 2016

Science Club Members


Minimum to send:

  • Rock – minimum 2″ / maximum 6″ (preferred 4″ size)
  • Name
  • Age
  • Address (to send certificate and sticker – not released)
  • Name of city/village and country (include zipcode if US)
  • Clean rock – wash with water if dirty (make free of dirt)

NOTE: Only First Names, Age, and Cities will be listed on the web


  • Latitude/longitude of sample site
  • Name of geographic feature (if it has one) where rock was collected
  • Copy of map with location where rock was collected
  • Picture of rock in person’s hand for scale
  • Picture of location where rock was collected (with no people)
  • Short paragraph describing area where rock was collected
  • Phone number

Place to Send Your Rock:

Dr. Phil Christensen
Mars Space Flight Facility
Arizona State University
PO Box 876305, Moeur Building Rm 131
Tempe, AZ 85287-6305


NASA Project by O & M Hostos School

August 29th, 2016

Martian Astrobiotic Tabletop Simulator

O & M Hostos School Science project in the Dominican Republic

Project lead Science teacher: Dale Albert Johnson Ph.D.


Food production for human occupation on Mars has revealed in Martian simulator experiments in the Netherlands, Denmark, and at the University of Wisconsin the importance of tubers such as potatoes that seem to thrive on simulated Martian soil. (Results of this work were featured in the film The Martian starring Matt Damon). The potato originated in Peru, first discovered by Spanish explorers in the 16th century. Tubers are a large part of the Latin diet. In the Dominican Republic on the Island of Hispaniola other types of tubers include Yucca and three types of Yautica.  Also. Due to the near lack of available nitrogen in Martian soil which is needed for plant growth, testing of a nitrogen fixer is needed. Guandule is a native nitrogen fixing plant of the Dominican Republic will be tested along with other nitrogen fixers. Thus a natural extention of the Mars astrobiotic simulator experiments is a comparative study of Dominican tubers and nitrogen fixers which will add to the data being collected worldwide by various Mars simulator programs.

O and M Hostos School Puerto Plata proposes to join and contribute to this worldwide network of Martian Simulator experiments using a table top model analogue of a Martian habitat. The science program at O and M Hostos Puerto Plata has joined the Globe program, a NASA supported educational initiative.

Creation and Preparation of Martian analogic soil.

Soil on Mars generally approximates volcanic soil on earth. It is high in iron, magnesium, and nickel among other chemical elements. Volcanic soil near Puerta Plata in the Dominican Republic created by volcanism of Loma Isabella de Torres is a near perfect analogue for Martian soil simulation. To create the soil we shall investigate sand, salt, and baking soda, and crushed serpentine stone reduced to dust the particle size for creating a  Martian analogue, in proper proportions to create a Martian analogic soil.

Introduction: Challenges

Mars explorations have provided information about the mineral composition of the soils on Mars. In addition to rocks they contain large amounts of sand-like soils or regoliths. All essential minerals for the growth of plants appear to be present in sufficient quantities in Martian soil except for reactive nitrogen. Nitrogen in reactive form (NO3, NH4) is one of the essential minerals necessary for almost all plant growth . The major source of reactive nitrogen on Earth is the mineralization of organic matter . However organic matter is absent on Mars. Nitrogen in reactive form (NO3, NH4) is one of the essential minerals necessary for almost all plant growth . Reactive nitrogen is part of the material in our solar system and is part of solar wind, a source of reactive nitrogen on the moon and Mars. Reactive nitrogen may also arise as an effect of lightning or volcanic activity  and both processes may occur on Mars. This indicates that in principle reactive nitrogen could be present . However, the Mars Pathfinder was not able to detect reactive nitrogen. Thus the actual presence of major quantities of reactive nitrogen remains uncertain. The major source of reactive nitrogen on Earth is the mineralization of organic matter , which is absent on Mars. The absence of sufficient reactive nitrogen may be solved by using nitrogen fixing species such as Guandule. In symbioses with bacteria  these nitrogen fixers are able to bind nitrogen from the air and transform it into nitrates, a process which requires nitrogen in the atmosphere. However, there is no atmosphere on the moon, and on Mars it is only minimally present and contains traces of nitrogen. Metals like aluminium and chromium are also present in the Martian soils. Aluminium is known to disturb plant growth and even lead to plant death. Another essential for plant growth is liquid water. Liquid water is very limited onMars. Ice is present on Mars and could be harvested. Many plant species may be grown hydroponically, e.g. tomatoes or paprika, but not all. Therefore, local soils could be used to grow crops.

Martian Greenhouse Simulator

A greenhouse is a simple technology that holds the promise to provide a continuous supply of all the food Mars astronauts or colonists will need. The question is what soil nutrients are required. What crops will provide human nutrition requirements? Is there a plant selection and regolith conditioning process that can be done simply enough to test in a Martian Astrobiotic Tabletop Simulator?

Our focus is use of Mars analogic soil to grow food crops. The Mars Greenhouse prove what food crops can grow on Mars adequate to sustain human life on Mars. Our experiments with Dominican indigenous crops will answer fundamental questions about what crops are best suited for Mars.

Selection of Native Dominican Crops

For our experiments we propose to test Yucca, Yautica Blanca, Yautica Amarilla, and Yautica Coco. For a nitrogen fixer we selected Guandule.

Building of the Simulator

Sheet plastic, led lights, plastic bins, Martian soil analogue, water, sample tubers and nitrogen fixing plants. Estimated cost: $85.00.




Regolith analysis by Sojourner

Martian Soil Chemistry.

Sojourner samples
A-2 A-4 A-5 A-9 A-10 A-15 Average
Na2O 4.1 4.2 4.4 2.2 2.5 3.8 3.53
MgO 9.7 9.0 8.0 7.3 8.4 7.5 8.32
Al2O3 9.8 9.9 9.8 9.8 9.2 9.3 9.63
SiO2 40.0 40.1 39.8 41.4 40.6 42.2 40.68
P2O5 0.8 1.0 0.5 0.7 0.5 0.5 0.67
SO3 5.9 6.8 5.6 6.7 6.3 5.2 6.08
Cl 0.7 0.8 0.8 1.2 0.8 0.7 0.83
K2O 0.5 0.5 0.5 0.7 0.4 0.7 0.55
CaO 5.9 5.5 5.9 6.4 5.9 5.4 5.83
TiO2 0.8 1.2 0.7 1.0 0.9 0.9 0.92
Cr2O3 0.3 0.4 0.5 0.2 0.3 0.3 0.33
MnO 0.5 0.4 0.2 0.1 0.4 0.3 0.32
Fe2O3 21.0 20.2 23.4 22.3 23.8 23.0 22.28


The regolith will have to be treated to create a suitable soil for plants. The first step is to create a plastic bag for the greenhouse structure and shovel in modified Regolith. Plants require some atmospheric oxygen for respiration. Adding water to the regolith will cause several chemical reactions, and release oxygen. If we assume Mars soil is oxides and not minerals, the chemistry is simpler but more reactions would occur. Sodium oxide [Na2O] will combine with chlorine [Cl] to form salt [NaCl] and release oxygen. Dissolved carbon dioxide will combine with water to form carbonic acid [H2CO3], which is an ionic compound consisting of 2 H+ ions and 1 CO3-2. Sodium oxide [Na2O] will also combine with carbonic acid to form soda. Dissolved soda will be indistinguishable between sodium carbonate [Na2CO3] and sodium bicarbonate (baking soda) [NaHCO3] due to the presence of H+ ions in water. Potassium is as ionic as sodium, so potassium oxide [K2O] will form potassium salt and potassium soda. Calcium oxide [CaO] will combine with sulphur trioxide [SO3] and water to form gypsum [CaSO4•2H2O]. Calcium oxide is also known as quicklime, which will react with water to form slaked lime and give off heat: CaO + H2O → Ca(OH)2. Phosphoric oxide will react with water to become phosphoric acid: P2O5 + 3 H2O → 2 H3PO4. Sulphur trioxide [SO3] will also react with water to form H2SO4, when dissolved in water that is sulphuric acid. What will the final pH be?

Site coming soon!

August 28th, 2016

This will be our science club site…

In the meantime we invite you to watch this video: