99942 Apophis
Published on Jan 27, 2007 at 12:50 pm.
29 Comments.
Filed under asteroids.
In June of 2004, Roy Tucker, David Tholen, and Fabrizio Bernardi discovered an asteroid. This particular asteroid was give the provisional designation 2004 MN4. Asteroids are discovered all the time, and normally, while cool for the ones discovering them, they don’t make much in the way of news. This one was different. Subsequent observations indicated that 2004 MN4 was going to pass very close to Earth on April 13, 2029. In fact, the observations available at the time were not sufficient to determine the orbit exactly, and the range of uncertainly overlaped the Earth’s position in space. The asteroid was assigned a Torino Impact Hazard Scale rating of 2. But, more observations indicated an even closer approach, with still considerable uncertainly. At one point, it was estimated that 2004 MN4 had about 2.2% chance of hitting Earth, and it was big enough to considerable damage, and to result in major devastation and death over thousands of square miles of Earth were it to hit. It was elevated to a level of 4 on the Torino scale — the highest of any body since the scale was developed. An intense campaign of observations over the next few days produced far better measurements of its position, allowing for much greater certainty in orbital calculations. Within a week, these improved calculations showed that the asteroid was unlikely to hit Earth, and its threat level was lowered to 1 on the Torino Scale. Subsequent observations showed that it is virtually certain to miss in 2029, though it will pass so close to Earth that it will be visible to the naked eye, perhaps even in urban areas, and it will pass well beneath our geosynchronous satellites. Interestingly, there is now a far greater chance of it hitting a satellite than of hitting Earth (No doubt, active satellites will be moved out of harm’s way, but dead satellites and space debris will remain in the danger zone). June 24, 2005, the IAU Minor Planet Center assigned a permanent minor planet number of 99942 to the asteroid. Soon afterwards, the discoverers named it Apophis, after the Egyptian god of chaos and destruction.
But, though it will probably miss in 2029, as the asteroid Apophis passes by Earth, its orbit will be altered. It will again pass very close to Earth in 2036, also on April 13. Former Apollo astronaut Rusty Schweickart noted in a letter to NASA Michael Griffin, that the uncertainly in the asteroid’s orbit was such that it was possible for the asteroid to pass on certain paths that would cause Earth’s gravity to change the trajectory enough for it to still hit Earth in 2036. In fact, while the 2029 pass seemed very unlikely to produce an impact, the 2036 pass seemed to remain a dangerous one. Further observations showed that it was quite unlikely to impact in 2036, and virtually certain to miss in 2029, so the Torino rating for 2029 was reduced to 0, and the rating for the 2036 pass was reduced to 1. This past fall, it was extimated that there is only a 1 in 45,000 chance of 99942 Apophis striking Earth, still uncomfortably high, given the consequences of an impact, but none-the-less, its Torino rating was dropped to 0. I should point out that a rating of 0 does not necessarily mean no chance of impact, but rather it means very little chance of impact.
At an estimated 320m across, were Apophis to strike Earth, it would likely strike with an energy of approximately one gigaton of TNT. That is like 1000 hydrogen bombs (note: H-bombs come in many different yields, so it might be only 100 big ones, or 2000 smaller ones). This is about five times larger than the impact that made Barringer Crater in Arizona. But, remember that an actual impact seems unlikely. Still, we don’t really know what asteroid orbits do. The Yarkovsky Effect has an annoying tendency to shift the orbits around a bit, and as critical as even a slight shift is to the computations, that means some unavoidable uncertaintly. So, we will keep watching this one.
There have been suggestions of launching a space probe to 99942 Apophis to monitor it, and to nail down the orbit more precisely. However, NASA has no budget to do this. This close approach also offers a fantastic opportunity to learn more about asteroids. Apophis will be passing so close that we can bring to bear instruments that we have not been able to use before with asteroids. Furthermore, it will be passing so close to Earth that the tidal forces from Earth will likely alter the structure of the body, or maybe even break it apart! This will be a great opportunity to study it. However, the breaking it apart idea is scary as all get outs. Because in that case, instead of one asteroid passing with a small chance of missing, there will be a cloud of smaller ones, spreading out, with the likelihood of at least one impact on Earth in 2036 becoming rather high. Apophis shouldn’t break up, but we know so little about asteroids …
-Astroprof
(Images courtesy NASA, JPL)
Emily Lakdawalla on January 27, 2007 at 1:17 pm: 1
Although NASA has no budget to send a spacecraft, The Planetary Society is seeking proposals for a mission design to tag Apophis, which will permit much more accurate tracking of this potential hazard. The competition is open to anyone; perhaps a team of your students would like to get together to submit a proposal! Some of the $50,000 prize money is set aside for the best student submission.
A Ler…-- Rastos de Luz on January 31, 2007 at 11:46 am: 2
[…] “99942 Apophis“, no Astroprof’s Page. […]
kate on March 4, 2007 at 10:31 pm: 3
hi iam like 12 and this stuff is so weird? is it really gonna be the end of the world or something?
Astroprof on March 4, 2007 at 11:15 pm: 4
No, it won’t be the end of the world, even if it were to hit Earth. And, by far the greatest likelihood is that is will miss us.
kigot on March 6, 2007 at 1:33 am: 5
Astroprof
How can one be so sure? Also, if it costs $1 Billion for NASA to track the whole sky, why can’t we just ask Bill Gates or his buddies to foot the bill…it won’t hurt them…and…ummm, I think, its worth it…well, maybe, the human race isn’t worth it…on second thought.
Steve on June 11, 2007 at 10:50 pm: 6
astroprof
so your saying that even in 2036, there is still a good chance, that it wont hit us??
- I was watchign this show called last days on earth on the history channel the other day and it REALLY FREAKED ME OUT- there were some things on there, that just made me extremely uncomfortable and depressed although i couldn’t turn the tv off!
Astroprof on June 11, 2007 at 11:56 pm: 7
Yes, it will most likely miss. That isn’t certain, but it probably will miss.
James Kendzierski on July 6, 2007 at 7:22 pm: 8
You might want to see my website http://ufotestpilot.com
Kathleen on July 9, 2007 at 1:26 am: 9
Apophis has already elicited panicky reactions from the population, a couple of whom have responded to your article, prof, and so we can probably rest assured that its exact path will never be revealed to us — until the last moment, perhaps, when its approach can no longer be denied. In my mind, it is suspicious that an asteroid has been spotted heading straight for Earth, and then two days later, it isn’t. Who is going to tell the truth when there is the chance of seven billion people running around, screaming in fear? My relief comes from knowing that a possible danger has been acknowledged with enough time to figure out how to remove the danger. Kate, in ten years, you could be through astroscience school and on a team that saves the world from an intruder. People freaked out by TV shows should, instead, trade their TVs for a telescope and then go look at the sky. Planetary shields are a cool idea (legend has it that there once was a shield), but a “giant screw” to attach it to the Earth? My personal favorite remedy is to blast white paint at the asteroid, causing it to absorb more heat from the sun, thusly altering its path. I mean, we have two decades in which to plan our actions. If we successfully turn away one itsy bitsy asteroid, then we will be able to turn away the other ones that are sure to make their appearances.
Astroprof on July 9, 2007 at 1:02 pm: 10
Well, this asteroid was never actually heading straight for Earth. Rather, it was heading near Earth and the margin for error overlapped Earth. That is what the astronomers said. The media then made it out to be on collision course. Later observations narrowed the margin of error so that we could say that it would likely miss. But, it does need to be watched.
Hadi on July 23, 2007 at 8:15 pm: 11
Well they say it will pass earth in 2029
but no one is sure if it will hit or if
it might trigger the pole flipping that is already overdue.
If ur wondering how maybe this asteroid might trigger the pole flipping is that
all asteroids when they pass they send magnetic waves to the earth and everywhere, so if apophis comes close it going to send magnetic waves which
no one is sure that the magnetic waves are going to interfere with the core and trigger the pole flipping and make the magnetic grid all messed up.Thats why im trying to figure out what Apophis is made out of, if its made out of metal most likely it will do more damage to the core once it gets close and sends its magnetic waves to earth.
I’m only 12 so it freaks me out the whole idea.
Astroprof on July 23, 2007 at 10:30 pm: 12
There is no way that any asteroid could have any major effect on Earth’s magnetic field like that.
Mark J. Carter on November 19, 2007 at 9:59 pm: 13
What is the calculated relative velocity of Apophis during the 2029 close approach?
Given its estimated range of passing, what is the Hyperbolic Excess Speed of Apophis during the 2029 approach calculated as Relative Speed at closest approach - Escape Velocity at Range?
Mark J. Carter on November 19, 2007 at 10:09 pm: 14
Deflection Strategies: An Alternative Approach.
Electro-magnetic Propulsion and Electro-dynamic Braking in Space Applications. – By Mark J. Carter
Space propulsion has changed little since mankind took its first tentative steps into space. Even with the incremental advances in the efficiency of chemical fuels; the basic nature of rocketry is still defined by the basic Delta V Rocket Equation with all its limitations; be it the powerful boosters used to obtain orbital velocity or the low impulse Ion Thrusters used to power deep space missions. This ancient approach to propulsion limits both the potential flight parameters of deep space missions and the life span of earth orbiting satellites.
In earth orbiting satellites, the electronics of the satellite may last indefinitely; but the useable lifespan of that satellite is limited by the availability of on-board propellants used for orbital maintenance. Once the chemical propellant is exhausted, the satellite no longer has the capability of maintaining proper station.
The International Space Station is dependent upon chemical propellants to offset orbital decay. The need and use of these chemical propellants increases the potential for catastrophic accident, increases the cost of operational maintenance, and requires the commitment of launch capacity for that purpose.
Interplanetary and deep space missions face similar limitations inherent to dependence on chemical propellants. Although gravitational assist has been a regular tool used in both navigation and imparting changes in specific orbital energy; obtainable velocities, launch windows, and other flight parameters remain severely limited by dependence upon the same Newtonian Propulsion methods used by the ancient Chinese to power their rudimentary rockets. Even Ion Propulsion, which uses electro-magnetic acceleration of the ion fuel to achieve impulse, is still a type of Newtonian Propulsion where the total energy imparted is limited by exhaust velocity and total available fuel mass as defined by the basic rocket equation. Newtonian Propulsion may have gotten us to earth orbit and beyond; but it will be Electro-magnetic propulsion that will carry us to the stars. In the mean time, its development will allow us to achieve flight parameters unimaginable when considering only chemical propellants.
The Ampere Defined As Magnetic Force:
Prior to 1948 the ampere was defined, based on Faraday’s Law Of Electrolysis, as the amount of unvarying current, that when passing through a solution of silver nitrate, deposits silver at a rate of .00111800 grams per second.
The ampere was redefined in 1948 as the amount of unvarying current, that when being carried by two infinitely long conductors separated by one meter, would generate a magnetic force between the conductors of 2 X 10-7 Newton per meter of length. This is the Standard International definition of an Ampere.
Electro-magnetic Propulsion and it’s inverse, Electro-dynamic Braking, when combined with the now and near term future technologies related to super conductivity, dielectric capacitance, and other related technologies; will introduce a new paradigm in space propulsion.
The Fundamentals Described As A Space Based Experiment:
A simple space based experiment to demonstrate the basic principles of electro-magnetic propulsion is easily imagined. In this experiment a simple coil, a number of accelerometers, a polarity reversing switch, power source, and radio telemetry is used to determine the earth’s electro-magnetic field strength at the range of the experimental package. It would be most advantageous if the coil length is as great as possible. The coil is circuited in series with the polarity reversing switch and the power source. The accelerometers serve to activate the polarity reversing switch. The experiment is then suitably packaged and conventionally launched to a low inclination orbit. The experimental package is then positioned so that the field coil of the package is aligned so the coil will be at maximum repulsion with earth’s electro-magnetic field when the coil circuit is initially energized.
So positioned, when the switch is initially closed and power is applied to the coil there will be two vector forces acting on the coil.
Since the coil is aligned in repulsion with earth field, one force will be acting along a line that is perpendicular to the earth’s North/South polarity (approximating the line of orbital radius) and will translate to an acceleration vectored along the orbital radius converting circuit energy to increased gravitational potential.
The other force acting on the field coil will translate to torque causing the field coil to begin to rotate about the central axis of the coil length as it begins to align towards the magnetic equilibrium position relative to earth field; that being one of maximum attraction and 180 degrees relative to the maximum repulsive position. In doing so, some of the electrical energy supplied to the field coil will be converted to kinetic rotational energy of the package. As the field coil rotates towards the equilibrium position, the accelerometer reading acceleration along the line of the orbital radius will sense zero acceleration as the angular relationship between the field coil and the earth’s North/South polarity reaches 90 degrees relative to the maximum repulsion or attraction position. The coil polarity control circuit is designed to reverse the polarity of the field coil at this position, thus maintaining a repulsive relationship as the rotational inertia carries the coil package through the 90 degree position.
The timing of the polarity reversing switch is critical for maintaining repulsion; avoid dampening the oscillation, or allowing the package to continue increasing its spin velocity.
As power is applied to the circuit, energy begins to be converted thru linear and rotational acceleration to the gravitational and rotational energy of the package. Without empirical proof, I suggest that the applied coil circuit energy will be the sum of the energy translated to gravitational potential and rotational kinetic energy. That the linear force acting along the line of orbital radius will vary as the cosine of the relative field angle while the force translated to torque about the center axis of the coil will vary as a sine function of the relative field angle. The linear force will approximate the force at 0 degrees (maximum repulsion) times the cosine of the relative field angle. The force imparting torque about the center axis of the field coil will approximate the force imparting torque about the center axis of the field coil at 90 degrees (maximum torque) times the sine of the relative field angle.
Where the moment of inertia of the experimental package is known, Earth’s Electro-Magnetic Field Strength can be derived from acceleration and circuit power.
Attitude Determination and Control Applications On Board Earth Based Satellites:
Using the Earth’s magnetic field as a reaction field in attitude determination and control of earth orbiting satellites was first proposed in the early 1960’s. Current applications include the sensing of relative field angle to determine satellite attitude and the use of electro-magnets to maintain and change satellite attitude. The author believes that widespread application may be limited by the orbital perturbation that would result from earth field/satellite field interaction. Electro-magnetic attitude control, without an Electro-magnetic orbital maintenance regime, would require expenditure of thruster fuel to maintain orbital station. To make electro-magnetic attitude determination and control a viable application, a means of offsetting the orbital perturbation using electro-magnetic propulsive technology rather than chemical thrusters must be developed. Also, the mass and volume fractions of electro-magnetic attitude determination and control technologies must be brought to values where the advantages of the technology offset the mass and volume fractions required. A primary advantage of Electro-magnetic propulsive methods for this application is that it can be accomplished without mechanical components as required in momentum and reaction wheel technology or the fuel and valving required for thrusters. This resulting increase in reliability will serve as further incentive to apply electro-magnetic technology to attitude control.
Increasing Hyperbolic Excess Speed in departure from Earth’s sphere of gravitational influence:
By definition, for an Earth orbital escape mission, the Hyperbolic Excess Speed is the residual speed that remains as the space craft climbs out of the Earth’s gravity well. Simply stated, it approximates the rocket burn out velocity minus the escape velocity at the range of burnout.
It may be possible to increase the Hyperbolic Excess Speed by using magnetic repulsive force generated by propulsion coils aboard the spacecraft acting against Earth’s electromagnetic field. The repulsive force would offset the deceleration of gravity as the space craft moves out of the Earth’s gravity well. This offsetting force would leave more residual or “Hyperbolic Excess Speed†as the space craft leaves the gravitational sphere of influence. If the magnetic repulsive force exceeds the gravitational force, then this force would continue to accelerate the space craft, imparting additional mechanical energy. The additional specific mechanical energy conserved or imparted would approximate the applied circuit energy calculated as applied power times time.
By thoughtful design, repulsion can be maintained without using an oscillating polarity strategy (as described in the Space Based Experiment), thus maintaining constant space craft attitude.
Increasing Hyperbolic Excess Speed in Gravity Assist Maneuvers:
A number of deep space missions have used Gravity Assist to either increase or decrease the mechanical energy of the space craft. Although such maneuvers use the gravitational acceleration of the assisting planet to increase or decrease the specific mechanical energy of the space craft, the Hyperbolic Excess Speed of the space craft relative to the assisting planet remains unchanged. The reason for this is the relative velocity between the space craft and the assisting planet gained by the acceleration of gravity on the approach trajectory is lost to that same gravitational force on the departure trajectory.
By using Electro-magnetic propulsion, additional hyperbolic excess speed can be imparted when the assisting planet has a significant magnetic field. In this application the propulsion coil(s) are used in attraction polarity on the approach to the assisting planet. This increases the acceleration above that imparted by gravity alone. As the space craft begins its departure trajectory from the assisting planet the relative polarity is reversed and maintained in repulsion; offsetting the deceleration imparted by gravity, thus increasing the Hyperbolic Excess Speed of the spacecraft relative to the assisting planet by adding the energy imparted by the electro-magnetic system to the specific mechanical energy of the space craft.
Orbital Station Maintenance and Altering Eccentricity:
By using properly timed Electro-magnetic Impulse, in repulsion and in attraction, possibly combined with Electro-dynamic braking; total orbital energy and eccentricity of orbit may be altered. Conceptualization of this regime involves both magnetic impulse and dynamic-braking at specific points in the orbit including using the induced dynamic-braking energy to produce vectored magnetic impulse.
Orbital Energy, often referred to as Specific Mechanical Energy, has two components. The kinetic energy per unit mass and the gravitational potential per unit mass. The sum of these two variables equals the specific mechanical energy. In an orbiting object, when not acted on by any other force other than the gravity of the prime focus object, this Specific Mechanical Energy remains constant. In elliptical orbits this energy translates between kinetic energy and potential energy as described by Kepler’s second law.
Introductory texts on Astro-dynamics teach that in most cases, a change in the Specific Mechanical Energy of a satellite is accomplished by imparting impulse along the velocity vector. This change in velocity translates to a change in the radius of orbit. By imparting impulse along the velocity vector the Specific Mechanical Energy can be either increased or decreased with the timing of the impulse relative to periapsis or apoapsis determining orbital eccentricity. Changes in apoapsis are made by imparting impulse at periapsis while impulse to change periapsis is imparted at apoapsis.
In both cases, the impulse either increases or decreases the total orbital energy by imparting a change in orbital velocity. This change in velocity is then translated to a change in gravitational potential by altering the semi-major axis.
It is proposed that changes in the orbital energy of the space craft can be made using Electro-magnetic technology; increasing the orbital energy by increasing the semi-major axis directly through repulsive interaction with earth field or decreasing orbital energy by electro-dynamic braking.
In a low inclination orbit, generating a magnetic field in repulsion with earth field will begin to impart impulse along the orbital radius, increasing the semi-major axis, thus directly increasing the gravitational potential component of the total orbital energy (Specific Mechanical Energy). By imparting magnetic impulse during the entire orbital period, or applying bit impulse relative to apoapsis and periapsis, the orbit can be stepped up and eccentricity controlled. If using conventional chemical propellants, stepping up the orbit is accomplished by increasing the velocity component, translating to gravitational potential, with the impulses timed relative to apoapasis and periapsis to control eccentricity. Experimentation with generating magnetic field in attraction to earth field may yield some surprising results. How will the circuit energy be conserved?
Electro-dynamic braking of the space craft will impart a braking force along the vector of orbital velocity, decreasing the orbital energy, and translated a reduction in gravitational potential. By timing the Electro-dynamic braking inputs relative to periapsis and apoapsis the orbit can be stepped down and eccentricity controlled. Using chemical propellants stepping down the orbit is accomplished by impulse opposite the velocity vector, slowing the spacecraft. The timing of braking impulse relative to periapsis and apoapsis will allow control orbital eccentricity.
Electro-dynamic Braking:
All electro-magnetic induction processes are composed of three primary components; the excitation field, the inductor, and rate of change. The rate of change can be supplied by velocity of the inductor relative to the excitation field, the oscillation of the excitation field in the presence of the inductor, or combination of the two.
For those of you who may have had the opportunity to empirically experience the fundamental physics of induction through experimentation with a simple hand crank generator, that lesson showed the relationship of circuit load to cranking force, and can be extrapolated to the inductive braking of a satellite or asteroid.
In the hand cranked generator, the permanent magnet supplied the excitation field for the induction process. The rotor, turning a coil through that excitation field, supplied the “Rate of Change†required for induction. The faster the rotor was turned the higher the voltage that was developed across the leads of the generator. When there was no “load†across those leads the generator was very easy to crank even though the “potential†or “voltage†was still being developed across the leads. But when a load, such as a light bulb, was placed in a circuit across the leads of the generator, that bulb created a “load†in the circuit. That “load†was the energy being dissipated in the bulb through resistive heating and light production. Supplying the circuit load with energy required greater force in cranking the generator. The force applied to the handle of the generator was converted to torque by the lever arm (handle) which spun the inductors (coils) at near right angles relative to the magnetic field (excitation field) of the stator. The energy required to spin the rotor was nearly equal to the energy being dissipated by the circuit “loadâ€. This is a good empirical example of the law of conservation of energy.
In Electro-dynamic braking applications the solar or planet field will provide the excitation field while coils aboard the spacecraft, or the spacecraft/asteroid body itself, serves as the inductor. The spacecraft/asteroid velocity cutting the flux lines of the Solar or Planet field will supply the rate of change component. This induction process will generate a braking force as is inherent in any electro-magnetic induction process. The induced energy will then be dissipated through circuits designed to generate heat for radiative dissipation, conversion to vectored propulsive impulse, or stored for peak power/subsystem applications. Applications of Electro-dynamic braking will include adjustments in semi-major axis and eccentricity; as well as braking to orbit in planetary missions.
Because the orbital velocity of a satellite or asteroid is so high, significant voltage can be developed even though the excitation field may be very weak. The “tether†experiments flown on the space shuttle clearly indicate the validity and potential application of this technology.
Imparting Orbital Escape Energy:
Escape speed, as given in reference material, gives the escape speed at the surface of the body referenced. This escape speed decreases as the radius of orbit increases. If an orbiting spacecraft is given continual magnetic impulse to step up the orbital radius, at some point, the orbital velocity of the spacecraft will approach and then exceed the escape speed at range, thus allowing the spacecraft to “escape†the gravitational sphere of influence of the prime focus body (planet or Sun). Using such a method, a satellite may be given Excess Hyperbolic Speed, not by imparting additional velocity, but by imparting additional gravitational potential until the Specific Mechanical Energy of the spacecraft exceeds that needed to escape the gravitational sphere of influence of the prime focus body.
By initiating high power Electromagnetic impulse in low earth orbit, very high Excess Hyperbolic Speeds may be obtained.
Braking to Orbit:
A space craft approaching Jupiter, or other target body, may have too much energy to establish orbit. By using Electromagnetic Propulsive methods it may be possible to alter both the magnitude and vector of the approach velocity; thus giving an alternative to using chemical propellants or atmospheric braking as the sole methods of reducing the energy of the spacecraft so that it can be captured by the intended prime focus body.
Deep Space Propulsion and Navigation:
In propulsion and Navigation, Electro-magnetic Propulsion will use electrical energy generated by an on-board power source to generate electromagnetic field(s) which will impart impulse through combined interaction with the magnetic fields of the Earth, Sun, Planets, and eventually, galactic fields.
Force vectoring will be obtained by very precise control of field strength, field angle, and action time relative to those reaction fields. Vector control, when within the magnetic sphere of influence of multiple field sources; will utilize the relationship of reaction field range, reaction field angle, and time span of power input to sum the force vectors from two or more reaction fields to obtain the desired net force vector. An example would be to act in repulsion of earth field for a fixed time at a fixed power and then act in attraction to Sun field for a fixed time at a fixed power. The net vector force would be the vector sum of the two forces. Because of the cosine relationship of repulsion/attraction force to the relative angle between the propulsion coil(s) and fields of the Sun, Earth, Jupiter, or other reaction fields, and if those fields are offset at a substantial angle relative to each other; effective impulse vectoring can be accomplished.
In Closing:
The Delta V imparted by a chemical rocket is limited by the attainable exhaust velocity of the rocket and total fuel mass available. In an Electro-magnetic Propulsion System capable of generating extreme field strength, the Delta V imparted will be limited only by the amount of available applied electrical power and the time span that power is made available.
In all cases, the minute field strengths of the reaction fields at range become usable when the propulsion system is capable of generating extremely strong fields or, in the case of dynamic braking, the induction circuit is capable of maintaining extremely high acceptance when dissipating high power.
The use of Electro-magnetic Propulsion may negate the requirement of waiting for opportune alignment of Jupiter and Saturn for use in Gravity assist maneuvers. The launch windows now continuously open by the ability to use Solar Field in repulsion to give the space craft the kick up that would otherwise require a gravity assist trajectory or maneuver.
A most important ramification of Electro-magnetic Propulsion and Electro-dynamic Braking in Space Applications may be the fundamental change in the logistics of asteroid deflection. This technology will negate the need to carry chemical fuel mass to the asteroid for the purpose of supplying impulse. It will allow mankind to use the orbital energy of the asteroid itself as the prime source of energy for deflection through an integration of Electro-dynamic braking, vectored electro-magnetic impulse, and as a power source for Newtonian Propulsion Systems that use scavenged mass from the asteroid and accelerate it using propulsion coils. Perhaps, it will cause a re-evaluation of the decision to use nuclear explosive deflection and fractionation as the preferred approach to this impending challenge.
Mujib on January 22, 2008 at 3:27 am: 15
Hi, i mujib. 99942 Apophis realy exist! i don’t understand why? why it will change its path to the world to show us the end of mankind. May be may be not.
Dusty in Texas on April 16, 2008 at 10:07 am: 16
*Tue Apr 15, 5:44 PM ET
(Yahoo news) - A 13-year-old German schoolboy corrected NASA’s estimates on the chances of an asteroid colliding with Earth, a German newspaper reported Tuesday, after spotting the boffins had miscalculated.
Nico Marquardt used telescopic findings from the Institute of Astrophysics in Potsdam (AIP) to calculate that there was a 1 in 450 chance that the Apophis asteroid will collide with Earth, the Potsdamer Neuerster Nachrichten reported.
NASA had previously estimated the chances at only 1 in 45,000 but told its sister organization, the European Space Agency (ESA), that the young whizkid had got it right.*
Ok, what the…?! Ummm… now what? Has the Torino gone up on this, or what? I mean, I don’t want to be chicken-little or anything, but this info kinda changes things, right? Should I be alarmed that no one else seems that alarmed?
Dusty in Texas
Astroprof on April 16, 2008 at 3:27 pm: 17
Dusty,
It turns out that the news report was wrong. I wrote about it here .
The J's on November 5, 2008 at 11:51 am: 18
Take liquid nytrogin in the center of the asteroid freezing it from the inside out and us C4 and or shoot a large missile at it to shatter it.
priscilla on February 24, 2009 at 12:32 am: 19
if everyone is so worried than ask god what you must do and the answer will be give our lives to god before it is too late for it is written that jesus will return in a blink of an eye. is the world coming to an end yes with each passing day so what if apophis is coming. so is jesus is anyone scared of that. think about it we all get in a frizzy when it comes to apophis how about we all get in a frizzy about jesus coming back. if the world is coming to its end than it is gods will and man can not stop gods will for it is said gods will be done. amen.
Nuker on May 29, 2009 at 11:19 am: 20
Hmm, in this article you implicitly tries to tell us that the barringer impact was about 200 megatons, which is in serious stride against all disciplines of physics. The energy involved in making that crater is almost 2 orders of a magnitude less, 4 megatons. The largest man made hydrogen bomb was equivalent to 100 megatons (perhaps slightly more) of TNT, tsar bomba. So this blast would be about 10 times larger. In theory, this could yield in a little more than twice the blast radius of tsar, if detonated in mid air. But this thing smashes with its force into the ground, where it is confined to a great extent by vaporizing a crater 7 kilometers across. So the destructive range would in fact be much less than that. If it smashed into the ocean, coastlines would be affected. Since a wave is a linear expanding ring, its power only decreases by a factor of 1/n instead of 1/n^2 for thermal radiation, and 1/n^3 for static overpressure.
200 megatons of TNT put into waves would do some damage certainly; The indian ocean 2005 tsunami was less than 10 megatons of TNT equivalent, and caused 250,000 deaths near coasts.
priscilla: Stop with your retarded propaganda of religious delusion.
The J’s: Haha, you have a very realistic idea. Not. If you knew even some basic physics, you would know that meteors are very cold objects, probably lying at -200 centigrades depending on their distance from the sun. Pouring nitrogen would heat it up instead. And how much nitrogen would it anyway take to affect those several dozen million tonnes of rock we’re talking about? And using C4? Dude, c4 wont have the least effect on that thing. First, its energy density would mean carrying a megaton of that stuff to space, to shatter the meteor. Not very realistic. But if we shot a thermonuclear weapon on the order of 25 megatons at that thing? There would be nothing left of it, just tiny droplets of vaporized rock flying out at kilometers per second, unable to condense ever again to meteors. Any small fragments hitting the earth would instantly be vaporized when smashing into the atmosphere.
Jon on November 24, 2009 at 8:46 am: 21
Are you kidding me? No Money to track it’s orbit more closely? Honestly, what the F is up with this world. Are we all taking crazy pills. This is beyond important, this is urgent. What if it does end up hitting us. Are we going to say “we just didn’t have any money.” Money is paper! It’s not real! It does not come with us when we die!
SOmetimes I want an astroid to hit us just to reset the ingnorance of our world. Clean slate, a new start.
Now that I think about it 99942 Apophis Sounds like a great Idea!
Jon on November 24, 2009 at 8:57 am: 22
Nuker… I too am not going to waste my time with Jesus… If he were to come again, then it should have been a long time ago.
Ps… I told my mom about this. I said wouldn’t it be great to go out with nature knowing you are part of history (rather than being murdered etc) or maybe just witnessing the close encounter? She freaked out on me… “what’s wrong with you? Why would you think like that?” People are missing out on life. Worrying about work, relationships, money etc… why can’t they just live and rock out with nature…which ever way it wants to take us?
cher on December 7, 2009 at 7:58 pm: 23
Okay you said that no asteroid can possibly make the poles switch places and lower the magnetic field and cause other calamities. What if the asteroid was made of the right metals that was magnetic repellent and it landed in say Antartica (where the south pole is for example), wouldn’t that cause a magnetic shift and or possibly a collapse of the magnetic field. Where i get this question from is I just saw a movie based on this sort of thing. It’s called Polar Storm. In the movie the near earth comet passed by the earth and a piece of the tail got free and did impact the earth. It was 300 meters wide and made of ice and rock. It landed in the Arctic Circle and it was enough to create enough force to start to collapse earth’s magnetic field over a period of days. Another question I have, is what if a large piece of a brown dwarf impacted the earth? Wouldn’t that have an effect on the magnetic field being as a brown dwarf is made of the heaviest of metals around? A piece the size of a match box can weigh apparently a thousand pounds. Something like that would be magnetic wouldn’t it? Yet again a movie was made about that too. If something like that were to threaten earth, how would we get rid of something so dense and so heavy without it harming the earth?? How do we really know that when the asteroid or comet that killed off the dinosaurs didn’t make a shift in earth’s magnetic field? Wasn’t most of the North American continent tropical at that time? Nowadays, at least were I’m living, it’s humid continental and or temperate. There’s been a shift somewhere and somehow. We just weren’t around to see it or record it. Sorry about the amount of questions. I’m just looking for answers. Thanks if you answer my many questions. I’m just wondering if these disaster movies do have any truth to them, or are they fictional..
Astroprof on December 8, 2009 at 8:52 am: 24
What is a “magnetic repellent”? The closest thing I can think of is a superconductor, and you wouldn’t find an asteroid made of that sort of material. No, these movies are just fiction. A very iron rich asteroid collision could possible locally distort the magnetic field, but not globally. Just look at the physics of the problem. There is far too much energy needed to do what you suggest, and even the kinetic energy of an asteroid doesn’t come close.
1Greensix on April 10, 2010 at 10:54 pm: 25
Will Apophis hit the Earth in 2029 or 2036? I think the answer to that is that two years after being discovered President Bush bought a 100,000 acrea ranch in Paraguay in 2006. He was told something the rest of us weren’t and I think there are a couple of people in CIA, NSA and the JPL that know the truth. I hope to be long dead and gone by that time, but I’ve told my kids they had better plan on being long gove from the west coast by 2028. The National Geographic Channel made a show called The Ultimate Tsunamiin 2006 that everyone had better see. It gave a pretty good description of what is going to happen when Apophis comes home. The tsunami and firestorm will be the end of a lot of lives. You don’t want to be in the Northern Hemisphere I’m tellin’ ya. And the Bush family won’t be.
jon on July 20, 2010 at 7:48 am: 26
apophis impact zone is Pacific Ocean… that’s if it “threads the needle” which they are not 100% sure of.. but if it does.. pacific ocean is the impact zone. Can’t wait for this light show!
Greg on December 18, 2010 at 9:33 pm: 27
We are safe based on all the data at the present time, however, if a plan to apply small amount of force over a short period of time by something launched from Earth into space can alter its orbit, then Apophis’ orbit has plenty of time to encounter a multitude of inconspicuous variable orbit altering forces between now and the first fly by. The most logical force being the heating and cooling by the sun of an object with an unknown shape and density tumbling through space for decades? We can calculate getting probes to far away places but how many tiny adustments are required after the initial imputs? What are the chances that a perfect field goal kicker will miss his next attempt?
Isaac M on January 27, 2012 at 12:02 pm: 28
I think that if it does hit us which it might or might not. Also this is just an idea try and shoot something on the rock like a tiny rocket and ignite the rocket to where it can change its direction. That is just an idea.
Isaac M on January 27, 2012 at 12:05 pm: 29
This is just an idea but NASA can try and plant a rocket on the rock and ignite it to where the rock can shift its orbit. hopefully it can work.