Home / Ride the Light – Japan will use Solar Sail; Germany, Fueled Craft, to Obliterate Apophis in 2015

Ride the Light – Japan will use Solar Sail; Germany, Fueled Craft, to Obliterate Apophis in 2015

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Earths scientists have anticipated the arrival of Apophis since 2002. Apophis, an asteroid of some size with a wide ranging eliptical orbit, will pass inside the orbits of our communication satellites (our geosynchronous zone) during 2029, and closer still in 2036. Apophis, the “serpent that dwells in darkness” is of unknown density, is 270 meters in diameter, and 460 feet long, weighing in, according to speculation, at about 46 million tons. Since the asteroid is traveling at a speed of 13,129 miles per hour, and in view of the fact that we know neither its mass, nor its direction of spin, it is impossible to predict with any certainty the probability of impact with our Earth.

Such an impact could wipe out half a continent. The asteroid that destroyed all life on Earth, and ended the Cretaceous period of Earth’s history, killing all the dinosaurs some 65 million years ago, was 6.2 miles across, and struck with the force of a billion times the atomic bombs that ended world war ll. Apophis, though somewhat smaller, if it were to make contact with our planet would do considerable damage.

Scientists know that Apophis like most objects in space has a spin, but are unsure of the direction of that spin. In scientific terms, retrograde motion is spin in the direction opposite to the movement of something else, in this case, the planet Earth, and is the contrary of direct or prograde motion. While we are told the likelihood of Earth impact is between 1 in 45,000 and 1 in several million, scientists quietly admit that they just can’t be sure yet. Spin and mass are required to make plausible conjecture. They are forced by circumstances to concede the possibility of a calamitous impact. Furthermore, in the event that the asteroid collides with one of our satellites, the outcome is still more unpredictable.

Scientists in Germany, and separately, in Japan, are developing ways to deal with Apophis, and any future asteroids they may threaten life on earth. In Germany, the European Space Agency is planning a mission using fuel driven rocketry to explode the asteroid into smaller particles, most of which will burn up in our atmosphere, with the remainder doing only minimal damage, should they reach the surface of our planet. A test mission is called Don Quijote; the mission name refers to (as we spell it) “Don Quixote”, the novel by Spanish author Miguel de Cervantes, about a knight-errant who tilted with windmills. In mission Don Quijote, An impact craft called Hidalgo will collide with an asteroid selected for the test, at a rate of 6 miles per second. The collision will be monitored by an orbiter called Sancho, and the outcome analyzed.

The Japanese, in the person of Shengping Gong and his team of scientists at the Tsinghua University in Beijing, are working in collaboration with the German team, and are utilizing new and still-in-development solar sail technology to change Apophis’ trajectory, and thus to avoid impaction. Solar sail space travel is inexpensive, and allows speeds of 9/10 the speed of light. In pursuit of Apophis, a small (10 kilogram) spacecraft driven by solar sail will orbit the Earth retrograde, building up speed for a collision course with Apophis. Collision velocity will be at 201,324 mph. The Japanese scientists say this impact in space will obliterate the asteroid into nothing.

400 years ago, Johannes Kepler proposed the idea of exploring the galaxy using sails to catch a theoretical “solar breeze.” Space vehicles would move among the stars, as sailing ships sail the ocean. Kepler’s solar breeze has been disproven, but NASA today, as is Japan, is experimenting with giant solar sails to push craft through the cosmos by light. A solar powered spacecraft doesn’t rely on soon-expended propellant, and so can voyage for decades, propelled by sunlight; the sun is its engine. NASA reminds us of the familiar tale of The Tortoise and the Hare. Conventional rocketry jumps to a quick start, like a hare or a rabbit. Light propelled vehicles, here compared to slow moving tortoises, take time to reach their high end speeds, but eventually will move five times faster than fuel driven rockets, and will be able to take man to the stars. NASA scientists write: “A solar sail would begin its journey at a slow but steady pace, gradually picking up speed as the sun continues to exert force upon it. Sooner or later, no matter how fast it goes, the rocket ship will run out of power. In contrast, the solar sail craft has an endless supply of power from the sun. Additionally, the solar sail could potentially return to Earth, whereas the rocket powered vehicle would not have any propellant to bring it back.” Once propelled into space by a traditional launch rocket, the sails are deployed using an inflatable boom system triggered by a built-in deployment mechanism, The small, compact parcel opens to a sizable sail to harness the power of the sun.

Some interesting notes of solar sailing: Arthur C. Clark popularized the phrase in May of 1964 in his short story, “Sunjammer”.

Japan, and the Japan Aerospace Exploration Agency, launched IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) in May of 2010, successfully demonstrating solar-sail technology in interplanetary space. “IKAROS” derives from “Icarus”, the tale of Daedalus, a young craftsman who attempted to escape from Crete on waxen sails, only to be foiled by the heat of the sun. The waxen wings unfortunately melted.

Images from NASA, and en.wikipedia.org

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About John Lake

John Lake had a long and successful career in legitimate and musical theater. He moved up into work behind the camera at top motion pictures. He has done a smattering of radio, and television John joined the Blogcritics field of writers owing to a passion for the liberal press, himself speaking out about the political front, and liberal issues. Now the retired Mr. Lake has entered the field of motion picture, television, and video game (now a daily gamer!) critique. His writing is always innovative and immensely readable!
  • A few misleading bits in this article.

    The purpose of the proposed Don Quijote mission is not to blow up an asteroid, but to see if one can be deflected in its orbit by means of an impact.

    The asteroid to be encountered has not yet been determined but will certainly not be Apophis, which (it actually is known with a high degree of certainty) will not impact Earth, at least not in 2036.

    A quick look around the ‘Net finds that a few journalists have leapt to the erroneous assumption that the ESA team is looking at Apophis, which I assume is how John came to do the same. In fact the mission profile specifically states that the target asteroid will not be one with an Earth-intersecting orbit, so that there will be no risk of the impact inadvertently deflecting it onto a collision course.

    Although the Japanese are pioneers in solar sail propulsion – they have a sail-powered vehicle en route to Venus right now – Shengping Gong and his team are Chinese, not Japanese.

    If Apophis does collide with a satellite during its close approach in 2036, the result will be the obliteration of the satellite. Apophis, being hundreds to thousands of times bigger, will not be affected much beyond acquiring a new crater.

  • John Lake

    While being ever conscious of a potential for panic, some publications, notably those from NASA, freely concede that none of the experts can be certain as to the probability of impact with apophis. At least one such expert has made the point that collision with one of our satellites may result in a course change by apophis and the resultant course can’t be predicted.

    In a paper by JD Giorgini in 2008, which won an Edward Stone Award for an Outstanding Research Publication, Giorgini compares the impossibility of computation to the situation of having 6 apples. He makes the comparison thusly: “The situation is similar to having 6 apples (the measured Apophis parameters) and 6 boxes whose contents are unknown (the unmeasured Apophis parameters). Boxes in hand, we then try to compute the probability that one has a total of 12 apples (impact probability). The result reflects back what is assumed about the unknown contents of the boxes, but fails to reveal new information. The contents of the boxes must be observed and measured to learn something new! Giorgini adds the variability brought about by solar energy, the heat of the sun, and concedes that the wide range of variables makes it impossible to predict if Apophis will have even a close encounter with Earth in 2036 when the orbital paths intersect.

    Here is a quote from NASA:
    “…However, additional factors can influence the predicted motion in ways that depend on rarely known details, such as the spin of the asteroid, its mass, the way it reflects and absorbs sun-light, radiates heat, and the gravitational pull of other asteroids passing nearby. These were examined, along with the effect of Earth’s non-uniform gravity field during encounters, and limitations of the computer hardware performing the calculations.

    “One would normally look for the influence of such factors as they gradually alter the trajectory over years. But, for Apophis, the changes remain small until amplified by passage through Earth’s gravity field during the historically close approach in 2029.

    “For example, the team found solar energy can cause between 20 and 740 km (12 and 460 miles) of position change over the next 22 years leading into the 2029 Earth encounter. But, only 7 years later, the effect on Apophis’ predicted position can grow to between 520,000 and 30 million km (323,000 and 18.6 million miles; 0.0035-0.2 AU). This range makes it difficult to predict if Apophis will even have a close encounter with Earth in 2036 when the orbital paths intersect….”

    An article from Asian Scientist, August 19, titled Scientists Propose Spacecraft To Save Earth From Asteroid Apophis In 2036 describes the solar sail experiment detailed in my article.

  • John, the paper you link to notes the following:

    1. Apophis will make an approach to Earth closer than the orbit of communications satellites in 2029. However, since the GEO satellites are in equatorial orbits, and Apophis will be on a trajectory of about 40 degrees relative to Earth’s axis, there is no possibility of a collision with one of them.

    2. The probability of Apophis impacting Earth has been estimated at about 1:45,000. If you play a slot machine, and there is a 1 in 45,000 chance that you will win the jackpot, there is a very high degree of certainty that you won’t.

  • John Lake

    The asteroid will come in at an extreme angle diminishing but not eliminating the threat of impact with satellites or other manmade materials. Such an impact would change the course of the asteroid, putting major parts of the world in danger. The odds are speculated to avoid popular panic. In fact, intervention is seen as needed.
    JD Giorgini, scientist and expert admits we really don’t have enough information to make a serious estimate of the impact probability.

  • I don’t find odds of 45k to 1 very reassuring. The odds of winning the UK lottery are around 14 million to 1 and there is at least one winner almost every week!

  • Chris: Yes, but with the lottery there are millions of people playing multiple lines and so the odds are good that somebody is going to guess right.

    (I actually remember one notable occasion shortly after the UK lottery started when 144 people won the jackpot in the same week – a freak probabilistic anomaly which I don’t think has ever been or will ever be repeated. I think they only won a few thousand each. Must have been quite a letdown!)

    To put the odds into perspective, Earth could have a close encounter with an Apophis every day and you would still only expect an impact every 123 years.

    John: I’m given to understand that the odds are sketchy right now because the current position of Apophis, between us and the Sun, makes it difficult to observe. Asteroid observers are promising a revised and more accurate impact probability in 2013, after which a more informed decision can be made as to whether any action needs to be taken.