After NASA’s DART mission’s successful impact on the Dimorphos asteroid, scientists have encountered a series of unexpected results, the most recent of which is the asteroid’s orbital period around its larger partner Didymos. was unexpectedly extended.
Last September, NASA’s $308 million DART (Double Asteroid Redirection Test) mission Deliberately collided with the asteroid Dimorphos. The refrigerator-sized spacecraft will collide with the 525-foot-wide (160-meter-wide) asteroid at speeds of up to 14,000 miles per hour (22,500 kilometers per hour), changing its orbit around its larger partner Didymos. It was intended for that purpose.This binary pair is located 7 million miles (11 million kilometers) from Earth It poses no threat to Earth, either before or after the redirect test.
This mission was a great success.This shock significantly changed the orbital period of Dimorphos around Didymos. The position will move several tens of meters in about 30 minutes. This achievement far exceeded the DART team’s goal of his 72 seconds and was the beginning of some unexpected results. This experiment suggests that Possibility of using kinetic impactors to change the direction of dangerous asteroidsBut the many questions raised by DART’s mission suggest there’s much more we need to understand first.
In the collision with Dimorphos, a strong recoil effect was observed. Dimorphos is believed to be an asteroid with a rubble pile made up of loosely bound rocks, pebbles, and dust, and upon impact, it ejected into space a huge amount of material known as ejecta.Speaking to Gizmodo earlier this year, Andy Chen, leader of the DART research team, said: explained He explains that the effect is similar to a small rocket engine: “It’s like a small rocket engine. There’s a recoil, a reactionary force from all the material flying off.” This recoil greatly strengthened the impact force. In fact, the propulsion force was nearly four times stronger than if the spacecraft had hit the asteroid without producing any ejecta, Chen explained, and the deflection was much more efficient than expected.
The second unexpected result of the DART experiment was that A “boulder cloud” appears around Dimorphos.. The impact threw about 2 million pounds of dust-laden rock into space, enough to fill six or seven railroad cars. Using the Hubble Space Telescope, astronomers identified nearly 40 rocks in the immediate vicinity of Dimorphos. Although these rocks pose no threat to Earth, their presence suggests that if we deflect a truly dangerous asteroid, potentially dangerous rocks could come toward Earth. Masu. our star.
A third unexpected discovery was recently announced at an American Astronomical Society meeting conducted by researchers from the Thatcher School and the University of California, Berkeley. The researchers used the 0.7-meter Thatcher Observatory in Ventura County, California, to measure Dimorphos’ orbital period 20 to 30 days after the impact. They found that its orbital period had been extended by about a minute, resulting in an initial 33- to 34-minute rotation around Didymus.
This is surprising, as the collision was expected to shorten its orbital period, and suggests that Dimorphos has been slowing down since the day of the collision. Scientists are perplexed by this observation. The arXiv preprint says: write:
We found that the mechanisms proposed so far for this system cannot explain such large periodic changes, and that drag from impact ejecta is unlikely to account for it. Further observations of the (65803) Didymos system are needed to confirm our results and further understand this system after a collision.
One theory suggests that Dimorphos’ orbit may be influenced by a giant debris cloud that is rapidly forming and evolving, developing into clumps, spirals, and other structures. However, the authors of the recent study are not convinced that this phenomenon is the root cause of the orbital period extension.
Before the DART mission, Dimorphos’ orbital period was already changing slowly. Still, the researchers say the observed differences cannot be explained by several known mechanisms. These include: Binary YORP effect (force from sunlight that changes the rotation of two orbiting bodies), mutual trends (effect of gravity between objects), Differential Yarkovsky force (pushing due to absorption of sunlight and release of heat), or as a result of sudden loss of surface mass.
Related article: NASA’s DART is now retired, but this future spacecraft wants to be revisited
Further observations and insights from more scientists are clearly needed on this issue. An important contribution to this research will come from the upcoming Hera mission. The European Space Agency (ESA) plans to launch the Hera spacecraft in October 2024 with the aim of closely studying the Didymos-Dimorphos binary star system and digging deeper into the results of the DART experiment. Including those strange and unexpected ones.
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