Spheres Definition and 504 Threads

The Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES) are a series of miniaturized satellites developed by MIT's Space Systems Laboratory for NASA and US Military, to be used as a low-risk, extensible test bed for the development of metrology, formation flight, rendezvous, docking and autonomy algorithms that are critical for future space missions that use distributed spacecraft architecture, such as Terrestrial Planet Finder and Orbital Express.Each SPHERES satellite is an 18-sided polyhedron, with a mass of about 4.1 kg and a diameter of about 21 cm. They can be used in the International Space Station as well as in ground-based laboratories, but not in the vacuum of space. The battery-powered, self-contained units can operate semi-autonomously, using CO2-based cold-gas thrusters for movement and a series of ultrasonic beacons for orientation. The satellites can communicate with each other and with a control station wirelessly. The built-in features of the satellites can be extended using an expansion port.From 2006, three SPHERES units are being used in the International Space Station for a variety of experiments. The SPHERES Guest Scientist Program allow scientists to conduct new science experiments using SPHERES units, and the Zero Robotics Program allow students to participate in annual competitions that involve developing software to control SPHERES units.The SPHERES program is expected to continue until 2017, and possibly further.The SPHERES project lead to a newer project called Astrobee.

View More On Wikipedia.org
Recent contents Top users
  1. D

    Gravitation between two spheres

    Hello, I'm new here :) I'm stuck on a homework problem, even though it's probably really easy and I'm just being stupid. Homework Statement In outer space, two solid spheres of radius 10.0 cm are held 30.0 cm apart center to center. One has a mass of 20.0 kg while the other has a mass of...
  2. P

    How Fast Do Two Identical Spheres Travel When They Meet in Space?

    Homework Statement Two identical 28.5-kg spheres of radius 12.1 cm are 35.3 cm apart (center-to-center distance) and at rest in outer space. (You can assume that the only force acting on each mass is the gravitational force due to the other mass.) a) If they are released from rest and...
  3. M

    Resistance in a Medium Between 2 Spheres

    Homework Statement Two small conducting spheres with radii a and b are imbedded in a medium of resistivity ρ and permittivity ε with their centers separated by a distance d >> a, b. What is the resistance R between them? Homework Equations R = V/I I = ∫JdS = (1/ρ)∫EdS The...
  4. S

    Expressing the interaction energy between two spheres?

    Homework Statement Two identical spheres with radius R have uniform charge Q throughout their volume and separated d>2R apart Homework Equations https://www.physicsforums.com/attachment.php?attachmentid=63061&d=1382054852 is the general potential energy equation this should be my...
  5. B

    Poissons ratio close-packed spheres

    Hello, See question 7.4 from the link. http://books.google.com/books?id=0N0...ow&w=685&w=800 "Assuming that atoms are hard elastic spheres, show that Poisson's ratio for a close-packed array of spheres is 1/3" I am having trouble explaining the proof for this. I know the that the...
  6. B

    Poissons ratio close-packed spheres

    Hello, See question 7.4 from the link. http://books.google.com/books?id=0N06swAJI0AC&pg=PA338&img=1&zoom=3&hl=en&sig=ACfU3U1qlbfJCRXsRow1xzu7hxEWOjYCow&w=685&w=800 "Assuming that atoms are hard elastic spheres, show that Poisson's ratio for a close-packed array of spheres is 1/3" I...
  7. Saitama

    Spheres hanging by strings - Finding impulse of tension

    Homework Statement Two equal spheres of mass m are suspended by vertical strings so that they are in contact with their centres at the same level. A third equal sphere of mass m falls vertically and strikes elastically the other two simultaneously so that their centres at the instant of impact...
  8. andyrk

    Connecting Charged spheres by a conducting wire

    When charged spheres are connected using a conducting wire, the charge will redistribute so as to make the potential constant because the connection makes them a single conductor and conductors are equipotential surfaces. My doubt was that if the spheres are of different size and have different...
  9. Z

    Electrostatics- spheres leaking charge

    Electrostatics-- spheres leaking charge Homework Statement Two small equally charged spheres, each of mass m, are suspended from the same point by silk threads of length d. The distance between the spheres x << d. Find the rate dq / dt with which the charge leaks off each sphere if their...
  10. D

    Moment of inertia of a bar with two spheres

    Homework Statement A dumbbell has two spheres of radius 0.10m and mass 10kg (each). The two spheres are connected using a bar with length 1.0m and mass 12kg. What is the moment of inertia of the dumbbell about an axis perpendicular to an axis at the bar's center of mass? Moment of inertia...
  11. W

    Two spheres travelling in opposite directions collide

    Homework Statement Two spheres of radius r move horizontally in opposite directions. The first has mass 2m and speed 2u, the second has mass m and speed 4u. The coefficient of restitution is (1/√3). The centres of the two spheres lie on two parallel lines, a distance r apart. (i) show that...
  12. 1

    Cubes, spheres, and derivatives.

    The volume of a sphere with radius r is v = \frac{4}{3}\pi r ^{3} It makes sense that its derivative with respect to radius is the surface area of the sphere. \frac{dv}{dr} = a = 4\pi r ^{2} The volume of a cube with side length n is n^{3} The derivative of this is just 3n^(2)...
  13. MarkFL

    MHB How many spheres are in a tetrahedral stack and what is its height?

    Consider a tetrahedral stack of spheres as in this image: Suppose there is a stack consisting of $n$ layers, and the spheres all have diameter $d$. Showing your work: a) Compute the number $N$ of spheres in the stack as a function of $n$. Then, express $N$ as a binomial coefficient. b)...
  14. W

    Oblique collision with two spheres one of which is at rest

    Homework Statement A smooth sphere of mass m collides obliquely with a smooth sphere of mass 2m which is at rest.The velocity of the mass m was 8i + 4j before impact, where i is along the lines of centres at impact.the m mass is then deflected through 90 degreese by the impact. find (i) its...
  15. W

    Oblique collision involving two spheres

    Homework Statement A smooth sphere of mass 4 kg collides obliquely with another smooth sphere of mass m which is at rest.After impact the two spheres move at right angles to each other.If the coefficient of restitution was (4/7), calculate the value of m. Homework Equations m1u1 + m2u2...
  16. T

    Collision of Uniform Smooth Spheres: Finding Coefficients of Restitution

    Help slove pls!:( A uniform smooth sphere P,of mass 3m, is moving in a straight line with speed u on a smooth horizontal table.Another uniform smooth sphere Q, of mass and m and having the same radius as P, moving with speed 2u in the same straight line as P but in the opposite direction to P...
  17. V

    Find Tension in String Connecting Two Charged Spheres

    Two charged objects of charge q. Coulomb's law states that the force on one sphere by the field of the other is: F = qE But each sphere experiences that, correct? So the tension for the string would be 2F. Is that correct?
  18. B

    Collision of a sphere into a cluster of spheres (billiard balls)

    Hello all, I am attempting to simulate collisions of pool balls. For the moment i am doing so without taking rotational momentum or friction between balls into account. right now i have a system that successfully simulates a collision between 1 ball and another ball. Here's how it basically...
  19. Saitama

    Electrostatic potential energy - dielectric between concentric spheres

    Homework Statement A conducting sphere of radius ##a## carries an initial charge ##q_o##. It is surrounded by another concentric sphere of radius ##b##. The space between the two spheres is filled with a dielectric of permittivity ##\epsilon## and conductivity ##\sigma##. Find the electrostatic...
  20. IridescentRain

    Calculating the density of optimally packed spheres

    Hello. I wish to calculate the density of optimally packed spheres (i.e. the fraction of space which is occupied by the spheres). This number is approximately 0.74, but I know this because I have looked on the net, not because I have calculated it. I know the essentials of how to calculate...
  21. P

    Force Between Two Conducting Spheres

    Hi physicists here. :) I've just joined the forums and here's my very first question :P : Aakash PHYSICS JEE (Main & Advanced) Study Package - 5 & 6 (Class XII) Chapter - Electric Charges and Field Assignment (page 12) SECTION - A; Q.no - 1 What I expected the answer to be was...
  22. Saitama

    Velocity of spheres after collision

    Homework Statement Three spheres, each of mass m, can slide freely on a frictionless, horizontal surface. Spheres A and B are attached to an inextensible inelastic cord of length / and are at rest in the position shown when sphere B is struck directly by sphere C which is moving to the right...
  23. M

    E field between 2 wrinkled spheres, radial symmetry?

    \oint E\cdot dA=|E|\int_{0}^{2\pi}\int_{0}^{\pi}(1+1/2sin6\theta\sin5\phi)^2sin\phi d\phi d\theta =|E|\int_{0}^{2\pi}(\frac{25}{99}sin^2(6\theta)+2) d\theta =|E|\frac{421\pi}{99}= \frac{\rho_{q}}{\varepsilon o}\int_{0}^{2\pi }\int_{0}^{\pi }\int_{0}^{(1+\frac{1}{2}sin6\theta sin5\phi...
  24. F

    AP Phyisics C E & M: Two Thin Concentric Spheres

    Homework Statement Two thin, concentric, conducting spherical shells, insulated from each other, have radii of 0.10 m and 0.20 m, as shown above(Graphic Above). The inner shell is set at an electric potential of -100 V, and the outer shell is set at an electric potential of +100 V, with each...
  25. M

    Exploring Coulomb's Law: Electric Field & Potential Diff. of Spheres

    Homework Statement Constant in Coulomb's Law: k = 9 x 10^9 Nm^2/C^2 1) Two metal spheres are each given a charge as shown below. They are initially placed 30 cm from one another (center-to-center distance). (Qa = -6 x 10^-7 C) (Qb = -4 x 10^-7 C) (Ra = 5cm) (Rb=2cm). A) For purposes of...
  26. M

    Electric Flux of Concentric Spheres

    Is we take two spherical conductors concentric with charge at centre.One of radius r then other of 2r..Will the electric flux through them will be equal? But when we use electric flux= E*A Then won't the electric flux vary as area is different of each sphere?
  27. D

    Electric field between two spheres

    Homework Statement If the inner sphere of radius a has charge +Q and the outer sphere of radius b has charge -Q/2. What's the electric field between them? The Attempt at a Solution If I use Gauss' law then I would have E*4*pi*a^2 = Q/ε then just solve for E. Is that correct? It seems...
  28. G

    Two conducting spheres connected by a wire

    Homework Statement Two conduction spheres with radius R1 og R2 are connected with a conducting wire. The length difference between the spheres is large enough to neglect any effect their respective electric fields have on each other. The total charge of the system is Q. Find the charges...
  29. Y

    Partition function for hard spheres on a lattice

    Hi everyone, I'm reading some lecture notes on statistical physics and thermodynamics and I'm stuck at an expression for a partition function which I really don't understand. The chapter is on mean field theory and the discussion is about hard spheres on a lattice. The interaction of the hard...
  30. N

    Conducting Spheres and Their Charge

    Homework Statement Suppose we have three identical conducting spheres and one of them carries a charge of Q. if they are lined up in a row and then separated one at a time without grounding them... a. only one will be charged with Q b. they will all be discharged c. one of them will have a...
  31. fluidistic

    Jackson's problem 4.10, dielectric between 2 spheres

    Homework Statement Two concentric conducting spheres of inner and outer radii a and b, respectively, carry charges +/-Q. The empty space between the spheres is half-filled by a hemispherical shell of dielectric (of dielectric constant ##\varepsilon / \varepsilon _0## ). a)Find the electric...
  32. A

    Two charged spheres are brought into physical contact with each other.

    Homework Statement Two charged spheres are brought into physical contact with each other. Initially, the charge on the first sphere was 2.34 nC, while the charge on the second sphere was -3.23 nC. a) What is the final charge (in C)on either charge?(2A) b) How many electrons moved...
  33. A

    Force between two charged spheres hanging from a string

    Problem Two small identical small spheres with mass m are hung from insulating threads of length L, as shown in the figure. Each sphere has the same charge q1 = q2 = q. The radius of each sphere is very small compared to the distance between them, so that they may be considered as point...
  34. F

    Calculating Charges of Identical Tiny Conducting Spheres

    Homework Statement You have two identical tiny conducting spheres: sphere A carries positive charge qA, and sphere B carries negative charge qB. First the spheres are placed distance d = 0.404 m apart, and they attract each other with a force F1 = 0.748 N. Then the spheres are brought...
  35. F

    Finding potential between identical spheres

    Homework Statement Two oppositely charged identical insulating spheres, each 56.0cm in diameter and carrying a uniform charge of magnitude 165μC , are placed 1.20m apart center to center. If a voltmeter is connected between the nearest points (a and b) on their surfaces, what will it read...
  36. L

    Electric potential of tiny spheres question

    Homework Statement Two tiny metal spheres A and B of mass mA = 3.40 g and mB = 3.90 g have equal positive charges q = 4.50 µC. The spheres are connected by a massless nonconducting string of length d = 1.00 m, a distance that is much greater than the radii of the spheres. (a) What is the...
  37. D

    Electric Field on Two Connected Spheres

    Homework Statement Two metallic spheres have radii of 19.1 cm and 11.5 cm, respectively. The magnitude of the electric field on the surface of each sphere is 3490 V/m. The two spheres are then connected by a long, thin metal wire. a) Determine the magnitude of the electric field on the...
  38. J

    Overlapping spheres of charge: finding the E field between them

    Homework Statement You have two spheres. The first is centered at the origin and as uniform positive charge density ρ and radius R. The second is shifted up a distance d, and it has uniform negative charge density -ρ and radius R. Find the E field in the region of overlap. Homework...
  39. A

    Shortest possible period of revolution of two identical gravitating solid spheres

    Homework Statement From K&K's 'Intro to Mechanics' Find the shortest possible period of revolution of two identical gravitating solid spheres which are in circular orbit in free space about a point midway between them. Homework Equations The Attempt at a Solution So I figured...
  40. I

    Estimating the Ratio of theta1 & theta2: Two Spheres with Unequal Charges

    Two spheres S1 and S2 hang from light insulating strings of the same length from points P1 and P2 which are on the same level. S1 is of mass M and has charge Q. S2 is of mass M and has charge 2Q. Repulsion between S1 and S2 causes their strings to be inclined at angles of theta1 and theta2 to...
  41. G

    Laplace Equation, Non-Concentric Spheres

    1. Homework Statement General solution for eccentric spheres, smaller sphere (radius, b) completely embedded within larger sphere of radius c. The centers of both spheres lie on z-axis, distance a, apart (note: c>b+a). Problem is symmetric, so consider θ=[0,∏], r=[0,c]. The inner sphere is...
  42. G

    Laplace problem for eccentric spheres

    Homework Statement General solution for eccentric spheres, smaller sphere (radius, b) completely embedded within larger sphere of radius c. The centers of both spheres lie on z-axis, distance a, apart (note: c>b+a). Problem is symmetric, so consider θ=[0,∏], r=[0,c]. The inner sphere is...
  43. C

    What is the Asymptotic Volume Fraction of Randomly Distributed Spheres in a Box?

    Hey guys, I need to fill up a box with uniformly distributed set of non-overlapping spheres. This is quite easy to do numerically. I was wondering what is expectation value for the asymptotic volume fraction of the spheres. Suppose I have a big box with side L, and spheres with radius R<<L. I...
  44. S

    Spheres and Planes Intersection

    Please bear with my ignorance. I will try to explain the complete scenario . I have a 3D cuboid (with planes as front, back, left, right, top and bottom) and three spheres called s1, s2 and s3. s1's center is at (2,4,5) and radius is 2. s2's center is at (-2,3,2) and radius is 1. s3's center is...
  45. D

    The distance between 2 spheres in pendulum

    Hi guys,first nice to meet you I am new here.Im working on a physics homework and i.ve already done it but i don't know why the x=2lsinx ( x=distance between 2 spheres in pendulum). (P.S sorry for my bad english,im from Germany). Is that from a trig identity? I think I've understand it but if...
  46. J

    Perfectly elastic collision of spheres

    Hey guys! I am currently developing a simulation that involves sphere (or if you like particle) collision in 3D space. And I want it to be accurate (on the level of classic mechanics). The algorithm to do the job would take in the velocities, masses and relative position (aka line of...
  47. M

    Concenctric spheres and electron

    Homework Statement Inside evenly charged (with charge Q < 0) sphere with radius R is evenly charged sphere with potential equal to potential in infinity and radius R/2. Both sphere are concentric. From internal sphere, tangentially to it fly out electron (with charge e < 0). What is minimal...
  48. L

    Double integration of circles, spheres etc

    Homework Statement So I have three questions. The first one is the double integration of x+2 from y=0 to y=sqrt(9^2-x^2). The second question is the double integration of sqrt(r^2-x^2-y^2) where the domain is in the circle of radius R and origin 0. And the last question is the double...
  49. morrobay

    Collision of Spheres: Equal Acceleration?

    If 3 spheres have equal masses and the stationary object is in a collision with a sphere with linear momentum . p= mv and linear speed 3m/sec And in the second case the collision with the stationary object is with a sphere with angular momentum L = rxp With angular speed 1 radian/ sec , radius...
  50. Vigardo

    Modelling drag force of big spheres in air.

    Hi all, I´m a researcher in computational biology thinking on topics quite far from my field. Would you help me? Thanks in advance! I want to calculate the drag force in air of big rigid spherical and cylindrical objects at speeds form 0 to 100 Km/h. Their diameter would range from 1 to 20m...
Back
Top