# Consider an asteroid with a radius of 19 km and a mass of 3.8×1015 kg. Assume the asteroid is roughly spherical

65,874 results

### physics

Consider an asteroid with a radius of 15.5 km and a mass of 3.46E+15 kg. Assume the asteroid is roughly spherical. What is the acceleration due to gravity on the surface of the asteroid? Suppose the asteroid spins about an axis through its center, like the Earth, with a ...

### Phsyics

In 2000, NASA placed a satellite in orbit around an asteroid. Consider a spherical asteroid with a mass of 1.00×1016 kg and a radius of 8.50 km. What is the speed of a satellite orbiting 4.70 km above the surface? What is the escape speed from the asteroid?

### Physics

In 2000, NASA placed a satellite in orbit around an asteroid. Consider a spherical asteroid with a mass of 1.00×1016 and a radius of 8.50 . What is the speed of a satellite orbiting 4.70km above the surface? What is the escape speed from the asteroid?

### Physics

In 2000, NASA placed a satellite in orbit around an asteroid. Consider a spherical asteroid with a mass of 1.00×1016 and a radius of 8.50km . What is the speed of a satellite orbiting 4.70km above the surface? What is the escape speed from the asteroid?

### physics

The Near Earth Asteroid Rendezvous (NEAR), after traveling 2.1 billion km, is meant to orbit the asteroid Eros at a height of about 15 km from the asteroid's center. Eros is roughly box-shaped, with dimensions 40 km 6 km 6 km. Assume Eros has a density (mass/volume) of about 2...

### physics

The Near Earth Asteroid Rendezvous (NEAR), after traveling 2.1 billion km, is meant to orbit the asteroid Eros at a height of about 15 km from the asteroid's center. Eros is roughly box-shaped, with dimensions 40 km 6 km 6 km. Assume Eros has a density (mass/volume) of about 2...

### Physics

The Near Earth Asteroid Rendezvous (NEAR), after traveling 2.1 billion km, is meant to orbit the asteroid Eros at a height of about 15 km from the asteroid's center. Eros is roughly box-shaped, with dimensions 40 km 6 km 6 km. Assume Eros has a density (mass/volume) of about 2...

### physics

An asteroid is discovered to have a tiny moon that orbits it in a circular path at a distance of 122 km and with a period of 43 h. The asteroid is roughly spherical (unusual for such a small body) with a radius of 19 km. (a) Find the acceleration of gravity at the surface of ...

### PHS 105

At a particular instant, two asteroids in inter-stellar space are a distance r = 20 km apart. Asteroid 2 has 10 times the mass of asteroid 1, m2 = 10 m1. 1. If the acceleration of the asteroid 1 toward the asteroid 2 is 1.0 m/s2 , what is the acceleration of the asteroid 2?

### Science

The Asteroid433Eros has a mass of 7.2 x 1015 kg, and a radius of = 11 km. What is the escape velocity of this asteroid (remember to use r in meters)? What consequence would this have for someone trying to walk on this asteroid?

### Physics- PLEASE HELP

Assume you are agile enough to run across a horizontal surface at 11.60 m/s on an airless spherical asteroid of uniform density 1.0x103 kg/m3, independently of the value of the gravitational field. To launch yourself into orbit by running, what would be (a) the radius? (b) the...

### physics

the near earth asteroid Rendezvous (NEAR), after travelling 2.1 billion km, is meant to orbit the asteroid Eros at a height of about 15 km from the asteroidal center. Eros is roughly box-shaped, with dimensions 40km x 6km x 6km. Assume eros has a density (mass/ volume) of ...

### physics

An asteroid, whose mass is 2.0 10-4 times the mass of Earth, revolves in a circular orbit around the Sun at a distance that is 2.9 times Earth's distance from the Sun. (a) Calculate the period of revolution of the asteroid in years. (b) What is the ratio of the kinetic energy ...

### Physics- Elena please help!

Assume you are agile enough to run across a horizontal surface at 11.60 m/s on an airless spherical asteroid of uniform density 1.0x103 kg/m3, independently of the value of the gravitational field. To launch yourself into orbit by running, what would be (a) the radius? (b) the...

### Physics

The asteroid belt circles the sun between the orbits of Mars and Jupiter. One asteroid has a period of 10 Earth years. a) What is the asteroid's orbital radius? b)What is the asteroid's orbital speed?

### Physics

Speed of Asteroids With the same Radius? Two spherical asteroids have the same radius R . Asteroid 1 has mass M and asteroid 2 has mass 2M. The two asteroids are released from rest with distance 10R between their centers. What is the speed of each asteroid just before they ...

### Physics

A uniform, solid, spherical asteroid with mass 1.2 * 10^13 kg and radius 1.0 km is rotating with a period of 4.6 hours. A meteoroid moving in the asteroid's equatorial plane crashes into the equator at 9.0 km/s. It hits at a 58° angle to the vertical and embeds itself at the ...

### physic

Between the orbits of Mars and Jupiter, several thousand small objects called asteroids move in nearly circular orbits around the Sun. Consider an asteroid that is spherically shaped with radius r and density 3000 kg/m3 . You find yourself on the surface of this asteroid and ...

### physics

Evidence suggests that there are trillions of dollars' worth of minerals and metals buried in Near Earth Asteroids (the ones that come close to the Earth, not the ones in the asteroid belt between Mars and Jupiter). Many scientists think an asteroid mining mission is easily ...

### physical science

Assume this asteroid has the shape of a sphere. A rock sitting on the surface of the asteroid has a weight of 100 newtons. What would the weight of this rock be if it were moved to a distance above the surface equal to the radius of the asteroid? It may be helpful to draw a ...

### physics

(a) What is the escape speed on a spherical asteroid whose radius is 435 km and whose gravitational acceleration at the surface is 0.632 m/s2? (b) How far (in km) from the surface will a particle go if it leaves the asteroid's surface with a radial speed of 535 m/s? (c) With ...

### physics

(a) What is the escape speed on a spherical asteroid whose radius is 435 km and whose gravitational acceleration at the surface is 0.632 m/s2? (b) How far (in km) from the surface will a particle go if it leaves the asteroid's surface with a radial speed of 535 m/s? (c) With ...

### physics

You're heading an international effort to save Earth from an asteroid heading toward us at 11km/s . Your team mounts a rocket on the asteroid and fires it for 10 min, after which the asteroid is moving at 21km/s at 32∘ to its original path. In a news conference, what do ...

### Physics

02. Comic-strip hero Superman meets an asteroid in outer space and hurls it at 800 m/s, as fast as a bullet. The asteroid is a thousand times more massive than Superman, yet in the comic strip, he remains stationary after releasing the asteroid. Say, his mass is 107 kg, what ...

### Algebra 1

Suppose a spherical asteroid has a radius of approximately 9.0 x 10^2m. Use the formula 4/3*pi r^3 to find the approximate volume of the asteroid. 2.57 * 10^9 m^3 1.07 * 10^4 m^3 2.54 * 10^10 m^3 4.51 * 10^10 m^3 I've worked 4/3*pi*10^2 = 900 meters... but now I'm confused, ...

### Physics

Two main strategies are employed to deflect an asteroid: destruction or slowing it down by at least 425 s so that the earth can move out of the impact zone. Assume perfect inelastic collision. (a) If we know the speed of the asteroid (va), mass (ma), and the distance the ...

### Physics

The Earth has an angular speed of 7.272·10-5 rad/s in its rotation. Find the new angular speed if an asteroid (m = 3.45·1022 kg) hits the Earth while traveling at a speed of 4.41·103 m/s (assume the asteroid is a point mass compared to the radius of the Earth) in each of ...

### Physics

(a) What is the escape speed on a spherical asteroid whose radius is 535 km and whose gravitational acceleration at the surface is 3.0 m/s2? 1 ? m/s (b) How far from the surface will a particle go if it leaves the asteroid's surface with a radial speed of 1000 m/s? 2 ? m (c) ...

### Physics

Given an acceleration of 0.6 m/s/s, on the surface of an asteroid with a radius of 1200 meters, find the mass of the asteroid.

### College Physics w/Calculus

(a) What is the escape speed on a spherical asteroid whose radius is 570 km and whose gravitational acceleration at the surface is 3.1 m/s2? (b) How far from the surface will a particle go if it leaves the asteroid's surface with a radial speed of 1000 m/s? (c) With what speed...

### earth-physics

The Earth has an angular speed of 7.272 10-5 rad/s in its rotation. Find the new angular speed if an asteroid (m = 1.07 1022 kg) hits the Earth while traveling at a speed of 1.30 103 m/s (assume the asteroid is a point mass compared to the radius of the Earth) in each of the ...

### Physics 20

Astronomers launch a satellite to explore a nearby asteroid that has come dangerously close to the earth.The satellite begins orbit around the earth,with an orbital radius 6.85 X 10^3 Km, before being moved to an orbit about the asteroid with a period of 9.06 X 10^3 S at a ...

### physics

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after it had passed the Earth. Suppose that at its ...

### physics

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after it had passed the Earth. Suppose that at its ...

### physics

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after it had passed the Earth. Suppose that at its ...

### physics help pleaseee

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after it had passed the Earth. Suppose that at its ...

### Physics

An asteroid has a mass of 3.66 x 10^20 kg and a radius of 8.2 x 10^5 m. If a 25 kg mass is dropped fro 10 m above the "ground" of the asteroid, how long will it take the mass to fall to the ground?

### physics

An asteroid, whose mass is 2.0 10-4 times the mass of Earth, revolves in a circular orbit around the Sun at a distance that is 2.9 times Earth's distance from the Sun. (a) Calculate the period of revolution of the asteroid in years. (b) What is the ratio of the kinetic energy ...

### Astronomy

1. Consider an asteroid of radius 2 km and density 2,500 kg/m^3 impacting the Earth. When it collides with the surface its kinetic energy is, to a large extent, dumped into the environment, some as heat vaporizing rock and some as mechanical energy throwing rock to great ...

### Astronomy

Imagine that the asteroid A that has an escape velocity of 50m/s. If asteroid B has twice the mass and twice the radius it would have an escape velocity _______ the escape velocity of asteroid A

### Physics

In deep space, a small rock orbits an asteroid. The circular, orbit radius is 1037m and the velocity of the rock is 8.02m/s. Find the mass of the asteroid.

### physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3740-kg space tug and a 6500-kg asteroid. They pull on the asteroid with a force of 470 N. Initially the tug and the asteroid are at rest, 480 m apart. How much time does it ...

### Physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3140-kg space tug and a 5050-kg asteroid. They pull on the asteroid with a force of 589 N. Initially the tug and the asteroid are at rest, 504 m apart. How much time does it ...

### Physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3830-kg space tug and a 5930-kg asteroid. They pull on the asteroid with a force of 671 N. Initially the tug and the asteroid are at rest, 514 m apart. How much time does ...

### science

Astronomers study an asteroid that is moving quickly toward Jupiter. Which statement describes how the gravitational attraction between the asteroid and Jupiter will most likely change? A. The gravitational force will increase as the distance between the asteroid and Jupiter ...

### Astronomy

Consider an asteroid of radius 2 km and density 2,500 kgm3 impacting the Earth. When it collides with the surface its kinetic energy is, to a large extent, dumped into the environment, some as heat vaporizing rock and some as mechanical energy throwing rock to great distance ...

### Algebra

Available evidence suggests that about 20 percent of the asteroid’s mass turned to dust and spread uniformly over Earth after eventually settling out of the upper atmosphere. This dust amounted to about 0.02 g/cm^2 of Earth’s surface. The asteroid very likely had a ...

### Physics

Asteroid satellite: While on its way to Jupiter in 1993, the Galileo spacecraft made a flyby of asteroid Ida. Images captured (Fig. P5.66) of Ida discovered that the asteroid has a tiny moon of its own, since given the name Dactyl. Measurements found that Ida to be about 55...

### Physics

An asteroid is moving along a straight line. A force acts along the displacement of the asteroid and slows it down. The asteroid has a mass of 4.5× 104 kg, and the force causes its speed to change from 7000 to 5000m/s. (a) What is the work done by the force? (b) If the ...

### Physics180

Tidal forces can break apart objects that orbit too close to a planet, producing rings like those of Saturn. Consider an asteroid 600km in radius, 65mm from Saturn's center. What's the difference in gravitational acceleration between the two sides of the asteroid?

### Physics

Two asteroids of equal mass collide as shown in the figure. After the collision, asteroid A’s trajectory is deflected by 30 degrees from its initial motion. Asteroid B is initially at rest and its final velocity makes a 45 degree angle with respect to the initial trajectory ...

### physics 12

A spacecraft of mass 470 kg rests on the surface of an asteroid of radius 1400 m and mass 2.0*10^12. How much energy must be expended so that the spacecraft may rise to a height of 2800 m above the surface of the asteroid? Thanks.

### Physics calculus based

Consider the Sun to be at the origin of an xy-coordinate system. A telescope spots an asteroid in the xy-plane at a position given by (x, y) with a velocity given by (vx, vy). [DATA: (x, y) = (3.3, 5.2) ×10^11 m; (vx, vy) = (-6.1, -4.0) ×10^3 m/s.] (A) What will the asteroid...

### p``

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3640 kg space tug and a 6500 kg asteroid. Using their ship's engine, they pull on the asteroid with a force of 490 N. Initially the tug and the asteroid are at rest, 500 m apart...

### physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3640 kg space tug and a 6500 kg asteroid. Using their ship's engine, they pull on the asteroid with a force of 490 N. Initially the tug and the asteroid are at rest, 500 m apart...

### Physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3360-kg space tug and a 6300-kg asteroid. Using their ship's engine, they pull on the asteroid with a force of 490 N. Initially the tug and the asteroid are at rest, 430 m apart...

### physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3580-kg space tug and a 6000-kg asteroid. Using their ship's engine, they pull on the asteroid with a force of 490 N. Initially the tug and the asteroid are at rest, 400 m apart...

### Physics

In deep space, a small rock orbits an asteroid. The circular, orbit radius (between their center of masses) is 1037 m and the velocity of the rock is 8.02 m/s. Find the mass (kg) of the asteroid. G=6.67x10^-11 m^3/kgs^2. I got 1.0x10^15 but that is incorrect.

### Physics

An asteroid revolves around the Sun with a mean orbital radius twice that of Earth's. Predict the period of the asteroid in Earth years. (6.38*10^6 radius) I don't understand how to solve this problem.

### physics

An asteroid is moving along a straight line. A force acts along the displacement of the asteroid and slows it down. The asteroid has a mass of 4.9 × 104 kg, and the force causes its speed to change from 7600 to 5400 m/s. (a) What is the work done by the force? (b) If the ...

### Physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3400 kg space tug and a 6000 kg asteroid. Using their ship's engine, they pull on the asteroid with a force of 490 N. Initially the tug and the asteroid are at rest, 420 m apart...

### Physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3760-kg space tug and a 6100-kg asteroid. Using their ship's engine, they pull on the asteroid with a force of 490 N. Initially the tug and the asteroid are at rest, 490 m apart...

### Physics

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3760-kg space tug and a 6100-kg asteroid. Using their ship's engine, they pull on the asteroid with a force of 490 N. Initially the tug and the asteroid are at rest, 490 m apart...

### physics

I need help finding an equation for: an asteroid revolves around the sun with a mean orbital radius twice that of Earth's. Predict the period of the asteroid in Earth years. Thank you.

### physics

A package of mass 9 kg sits at the equator of an airless asteroid of mass 4.0 1020 kg and radius 4.9 105 m. We want to launch the package in such a way that it will never come back, and when it is very far from the asteroid it will be traveling with speed 185 m/s. We have a ...

### physics

A steroid is moving along a straight line. A force acts along the displacement of the asteroid and slows it down. The asteroid has a mass of 4.5e4kg and the force causes the speed to change from 7100 to 5500m/s. (A) What is the work done by the force? (B) If the asteroid slows...

### science

As mentioned before, our asteroid is in the shape of a sphere and has a mass of 2000 kilograms. Determine the density (in grams per cubic centimeter) of this asteroid if its diameter is known to be 1.2 meters.

### physics

Assume you are agile enough to run across a horizontal surface at 8.10 m/s on an airless spherical asteroid of uniform density 1.9x103 kg/m3, independently of the value of the gravitational field. To launch yourself into orbit by running, what would be (a) the radius?

### physics

Assume you are agile enough to run across a horizontal surface at 8.10 m/s on an airless spherical asteroid of uniform density 1.9x103 kg/m3, independently of the value of the gravitational field. To launch yourself into orbit by running, what would be (a) the radius?

### physics

Find the radius of a spherical asteroid that has a density of 4600 kg/m3 and an acceleration due to gravity of 0.11 m/s2 at the surface. km

### Physics

An asteroid heads for Earth at 12 km/s. In addition, a NASA space team is able to attach a rocket booster to the asteroid, which then allows the asteroid to move at 28 degrees to its original path to a speed of 20km/s. What is its average accleration for acceleartion at (x) ...

### Physics

An asteroid heads for Earth at 12 km/s. In addition, a NASA space team is able to attach a rocket booster to the asteroid, which then allows the asteroid to move at 28 degrees to its original path to a speed of 20km/s. What is its average accleration for acceleartion at (x) ...

### Physics

The asteroid EROS has a mass of 7.4x10+15kg. A 103kg astronaut stands on the surface, 33km from the centre of the asteroid. What weight does she experience ? Give your answer in Newtons. Take the Gravitational constnat, G, to be 6.67x10-11.

### Physics

An asteroid with mass m = 1.85*10^9 kg comes from deep space, effectively from infinity, and falls toward Earth. How much work would have to be done on the asteroid by friction to slow it to 550 m/s by the time it reached a distance of 1.50*10^8 m from Earth?

### physics

Influenced by the gravitational pull of a distant star, the velocity of an asteroid changes from from +19.0 km/s to −19.4 km/s over a period of 1.85 years. (a) What is the total change in the asteroid's velocity? (Indicate the direction with the sign of your answer.) (b...

### Physics-Update

An asteroid heads for Earth at 12 km/s. In addition, a NASA space team is able to attach a rocket booster to the asteroid. The rocket booster fires for 10 min after which the asteroid is moving at 28 degrees to its original path to a speed of 20km/s. What is its average ...

### Circular motion Problem - Please! need HELP!!!fast

An asteroid in space is attracted to the planet XYZ such that it accelerates at 0.0085 m/s^2 towards it. Given that planet XYZ has a mass of 4.7*10^24 kg. How far out from the planet is the asteroid?

### Physics

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after it had passed the Earth. Suppose that at its ...

### help help help

The asteroid belt between Mars and Jupiter consists of many fragments (which some space scientists think came from a planet that once orbited the Sun but was destroyed). (a) If the center of mass of the asteroid belt is about 2 times farther from the Sun than the Earth is, how...

### physics/orbital speed

an asteroid orbits the sun at a constant distance of 4.44e+11 meters, the suns mass is 1.00*10^30kg, what is the orbital speed of the asteroid? Please explain step by step thanks

### Calc Physics

The velocity as a function of time for an asteroid in the asteroid belt is given by v(t)= vo e^(-t/to)i + (vo t/ 2 to) j with vo and to constants. Use ti = 0 as the initial time, and tf = 472 s as the final time. The values for the constants that you will use are: vo = 9 m/s ...

### physics

A space probe is to be put into a circular orbit of radius 42.00 km about an asteroid. At this radius the magnitude of the gravitational acceleration, normally referred to as the "gravitational field", is 1.00×10-3 meters per second squared. What speed, in meters per second, ...

### physics

Consider the Sun to be at the origin of an xy-coordinate system. A telescope spots an asteroid in the xy-plane at a position given by (1.8 1011 m, 3.1 1011 m) with a velocity given by (-8.4 103 m/s, -6.3 103 m/s). What will be the magnitude of the asteroid's velocity and it's ...

### Math

An astronomical researcher is using software to study the parabolic path of an asteroid. By entering the equation for the path of the asteroid, the researcher could determine if the asteroid would collide with any other bodies in the near future. The equation for the asteroid...

### Physics

A ball is tossed straight up from the surface of a small spherical asteroid with no atmosphere. The ball goes to a height ewual to the asteroid's radius and then falls straight down towardd the surface of the asteroid. What forces if any act on the ball while it is on the way ...

### Physics

Comic-strip hero Superman meets an asteroid in outer space, and hurls it at 750 m/s, as fast as a bullet. The asteroid is three thousand times more massive than Superman. In the strip, Superman is seen at rest after the throw. Taking physics into account, what would be his ...

### Physics

A particular asteroid has a circular orbit about the Sun with a radius of 450 million miles. How long does it take to go around the sun? Compare the prediction of Kepler's 2nd law to a direct computation with Newton's 2nd law. How much area does the line connecting the ...

### Science

Where is the "asteroid belt" located? Thank-you for all your help. http://www.onelook.com/?w=asteroid+belt&ls=a

### physics

An asteroid moves toward the sun along a straight line with a velocity given by v = -(c1+c2/x)½ , where x is the distance from the center of the sun. Use the chain rule for derivatives to show that the asteroid's acceleration is a = -c2 /2x^2.

### Physics

A ball is tossed straight up from the surface of a small spherical asteroid with no atmosphere. The ball goes to a height ewual to the asteroid's radius and then falls straight down towardd the surface of the asteroid. What forces if any act on the ball while it is on the way ...

### physics

One cubic centimetre (1.0 cm3) of water has a mass of 1.0 × 10−3 kg. (a) Determine the mass of 1.0 litre of water. Assuming that biological substances are 98% water, estimate the masses of (b) a cell with a diameter of 1.0 μm, (c) a human kidney, and (d) a fly. ...

### Astronomy

A roughly spherical asteroid with a diameter of 1 km, and a mean density of 4 g/cm^3, hits the Earth with a relative speed 1.5 times the orbital velocity of the Earth. Compute the amount of energy released upon the impact. Compare that with the energy released by a 10-Megaton ...

### Astronomy

Consider the same asteroid initially in the asteroid belt at a distance 3 AU from the Sun, and 2 AU from Earth, which collides with Earth. As it falls towards Earth, it acquires kinetic energy (neglect its initial motion) both by being accelerated towards the Sun and towards ...

### Physics

The moment of inertia of an asteroid rotating about its own axis is 5.00 ! 10 4 kg"m2. Its angular velocity is 40.0 rad/s. If a force acts on the asteroid for 0.100 s, increasing the angular velocity to 48.0 rad/s, find its magnitude

### physics

Asteroids can be classified into two broad groups based on their composition and location: carbon-rich asteroids dominate the outer part of the asteroid belt, whereas metal-rich asteroids dominate the inner part of the belt. Analysis of the fragment we have discussed in this ...

### Physics - pendulum

A pendulum that on Earth has period 0.52 s is taken to the surface of a large asteroid, where it is measured to have period 1.7 s. What is the value of the gravitational acceleration on the surface of that asteroid?

### physics

The asteroid Ceres has a mass 7.061 × 1020 kg and a radius of 505.2 km. What is g on the surface? The value of the universal gravitational constant is 6.67259 × 10−11 N · m2/kg2.

### Physics

What is the change in angular momentum of a planet with radius R if an asteroid mass m and speed v hits the equator at an angle from the west, 40 degrees from the radial direction?

### Force, Gravity, Resultant Force, Vectors

Can someone just have a quick look over this question and my current answers and tell me if there are any massive mistakes im making. I feel confident with what ive done but just need a little boost. Question: An asteroid of mass m =7 .5×10^12 kg has two rocket thrusters ...