NASA's nuclear attack on asteroid Bennu to save Earth

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NASA’s nuclear attack on asteroid Bennu to save Earth
NASA’s nuclear attack on asteroid Bennu to save Earth

New Delhi : NASA scientists have predicted that an asteroid, named Bennu may attack Earth around September 21, 2135. In order to save our planet, the team is setting up plans for nuclear attack on this large rocky body which have chances to collide with the Earth in future. They are preparing nuclear bombs for the space war.

Though there is 1 in 2,700 chance of crashing to Earth, yet, NASA wants to ensure that the possible danger must be deactivated advance. Sources confirmed that experts have no plans to destroy the asteroid directly. They said that if the Bennu asteroid is found to approaching too close to Earth, then it has to be destroyed with nuclear bombs to guarantee the safety of the planet. 

As per scientific record, Bennu is orbiting the Sun at about 54 million miles away from Earth. The asteroid is about 1,600 foot wide and weighs around 74 billion pounds. It is likely that the asteroid Bennu will come very close to Earth in September 2135. As a result, there might be a probability of collision of the asteroid with Earth.

Accordingly, NASA along with the National Nuclear Security Administration and two Energy Department weapons labs will design and develop a spacecraft called HAMMER. By the term ‘HAMMER’ scientists mean Hypervelocity Asteroid Mitigation Mission for Emergency Response. They consider that HAMMER spacecraft would be able to deliver nukes to the asteroid. The scientists are thinking of two ways in which they can obstruct Bennu from coming very close to Earth. If the asteroid is found to be small, then the HAMMER spacecraft will use an 8.8-ton “impactor” to crash the asteroid. If the asteroid is a large one, then the HAMMER will destroy it with nuclear bombs before it hits the Earth.

However, Physicist David Dearborn from the Lawrence Livermore National Laboratory has a view that there is no need of any nuclear bombing. Dearborn recommended that the progress of asteroid could be slow down and its path could be changed by attacking it with multiple HAMMER crafts. They said that the ‘HAMMER concept’ was earlier introduced in a 2010 report published in the journal Acta Astronautica and not a new thing in the space attack mission. As per the report, the use of a spacecraft functioning has either a kinetic impactor or a nuclear explosive carrier to redirect the approaching NEO. But, it is also true that the future of HAMMER project is undecided and NASA is currently studying the ‘OSIRIS-Rex mission’ that is on its way to Bennu to gather data and convey them back to Earth.

As per the US space agency NASA, OSIRIS-REx is progressing towards outbound cruise operation which is on the way to arrive in December of 2018 at the asteroid Bennu. The approach is likely to start on the month of August. Records say that spacecraft is currently 29.6 million miles (47.6 million kilometers) from Earth and is carrying out a program intended to study and minimize the availability of water on the spacecraft.

During regular ‘in-flight testing’ of the spacecraft’s thermal properties, the mission’s navigation team observed an unexpected minor acceleration of the spacecraft when the Sample Return Capsule (SRC) was bare to sunlight. The team determined that this small thrust was caused by the out gassing of water that had been absorbed by the SRC’s heat shield and back shell before launch.  Retention of water in blanketing and other materials – and the subsequent out gassing of this water – occurs with all spacecraft. For OSIRIS-REx, it was resoluted that when the SRC was exposed to the Sun at a distance of less than 1 Astronomical Unit (1 AU = approximately 93 million miles), this trapped water escaped and passed on to a small thrust. However, this small thrust would not be a big problem for other mission but since the gravity at the target asteroid Bennu is low therefore even this small amount of thrust could make orbital operations more difficult for OSIRIS-REx.

To have better understanding of the out gassing effects on the spacecraft’s trajectory – and to heat up the remaining water before the spacecraft arrives at Bennu – the OSIRIS-REx mission team has planned an outgassing program for implementation which is about to start, earlier this fall. The selection of timing has been made in accordance with the spacecraft’s proximity to the Sun (less than 1 AU) and the fact that there were no other science performance planned during this period. The out gassing program is being run simultaneously with outbound cruise operations and does not affect the timing of the spacecraft’s arrival at Bennu.

In the mid-October, the spacecraft has been positioned into various attitudes to interpret different parts of the SRC to direct sunlight and initiate outgassing. Priority is given to the portions of the SRC that will face the Sun during asteroid proximity operations. The team has been able to detect and measure the rate of outgassing at each attitude and has determined that water is being removed as expected. The objective is to reduce the outgassing to the point where the spacecraft can fly the designed baseline trajectories around Bennu without modifications, and preliminary indications show that the program is progressing toward this goal. The program has been scheduled to run all the way through early January 2018.

About ‘Bennu Asteroid’

The ‘101955 Bennu’ (provisional designation 1999 RQ36) is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on September 11, 1999. It is a highly hazardous object that is listed on the Sentry Risk Table with the third-highest rating on the Palermo Technical Impact Hazard Scale, due to a cumulative 1-in-2,700 chance of impacting Earth in the late 22nd century. It is the intended target of the OSIRIS-REx mission which is planned to transfer samples to Earth in 2023 for further study.

Scientists says that Asteroid Bennu has a approximately ‘spheroidal shape’, which resembles a spinning top. The direction of rotation about its axis is retrograde with respect to its orbit. It has a fairly smooth shape with one prominent 10–20 m boulder on its surface, in the southern hemisphere.

Also, there is a definite point along the equator of asteroid Bennu. The presence of this point indicates that fine-grained regolith particles have gathered in this area, probably due to its low gravity and fast rotation.

As per the observations of this minor planet made by the Spitzer Space Telescope in 2007, an effective diameter of 484±10 m rows up with other studies. It has a low visible geometric albedo of 0.046±0.005. The thermal inertia was calculated and found to vary by ±19% during each rotational period. The data says that the regolith grain size is moderate, ranging from several millimeters up to a centimeter, and evenly distributed longitudinally. Till now, no emission from a potential dust coma has been detected around asteroid Bennu, which puts a limit of 106 g of dust within a radius of 4750 km.

On an average, the asteroid with a diameter of 500 m (1,600 ft; 0.31 mi) can be expected to impact Earth about every 130,000 years or so. A 2010 dynamical study by Andrea Milani and collaborators guessed a sequence of eight potential Earth shock by Bennu between 2169 and 2199. The cumulative probability of impact is directly proportional to the physical properties of Bennu that were inadequately known at the time, but was not found to exceed 0.071% for all eight encounters. The authors documented that an accurate assessment of 101955 Bennu‘s possibility of Earth impact would call for a detailed shape model and additional observations (either from the ground or from spacecraft visiting the object) to determine the magnitude and direction of the Yarkovsky effect.

The publication of the shape model and of astrometry based on radar observations acquired in 1999, 2005, and 2011, made potential an enhanced estimate of the Yarkovsky acceleration and a revised evaluation of the impact probability. The current (as of 2014) best estimate of the impact probability is a cumulative probability of 0.037% in the interval 2175 to 2196. This data is equivalent to a cumulative score on the Palermo scale of −1.71. If a collision were to occur, the expected kinetic energy associated with the impact would be 1200 megatons in TNT equivalent.  

So, let’s wait to watch NASA’s preparation to attack on Bennu Asteroids. Stay tuned for more Science related information!