Last week, the Japanese Aerospace Exploration Agency (JAXA) launched an explosive warhead on the surface of the 162173 Ryugu asteroid. I might think that this was the first line of a completely readable science fiction novel, but it is totally true. The operation began on April 4, when the Hayabusa2 The spacecraft sent its Small Transport Impact (SCI) to the surface of Ryugu and then detonated it to create a crater.
This is the last phase in the Hayabusa2The mission of studying and returning samples of a Near Earth Object (NEO) in the hope of learning more about the formation and evolution of the Solar System. This began shortly after the spacecraft met with Ryugu in July 2018, when the ship deployed two rovers on the surface of the asteroid.
This was followed by the spacecraft that sent the box-shaped mobile asteroid surface landing module (MASCOT) to the surface, which badyzed samples of the asteroid regolith in two locations. And last February, the spacecraft landed on the surface for the first time, resulting in the collection of the first samples of the mission.
However, before the samples could be recovered, the ship had to divide the surface material by firing it with "bullets": impactors of 5 grams made of metallic tantalum that are fired from the ship's sampling horn at speeds of 300 m / s (670 mph). The same principle is behind the SCI, a system consisting of a 2.5 kg (5.5 lb) copper projectile.
This "bullet" is accelerated by a shaped charge containing 4.5 kg (~ 10 lbs) of plasticized HMX explosive (also known as octogen). This compound is the same one used by the military forces as the detonator in nuclear weapons, in plastic explosives and as a solid rocket propellant. When combined with TNT, it creates octol, another military-grade explosive used in anti-tank missiles and laser-guided bombs.
After sending the SCI to the surface, the ship was raised to a safe altitude to avoid any damage from the explosion. Then the SCI was detonated, sending a copper plate to the surface at 1.9 km per second (1.2 miles per second). The size of the crater that this generates will depend completely on the composition of the material of the surface.
the Hayabusa2 He captured the launch of the SCI with his wide-angle optical navigation camera (ONC-W1), which they shared on the official Twitter page of the mission. The explosion was also captured by a deployable camera, the DCAM3, which the spacecraft deployed closer to the asteroid to monitor the impact experiment.
The camera was destroyed in the process, but the images it took will help. Hayabusa2 Locate the crater once it approaches the surface again. This will take place after all the debris has settled; At that time, the mission team will determine if it is safe or not to obtain a sample from the newly created crater.
If this recovery is considered too dangerous, the ship will head to one of the asteroid's pre-existing craters. However, the team hopes to obtain samples from the crater they created, since the material discovered by the explosion has not been exposed to space and subjected to radiation and space weather for billions of years.
This is consistent with a central objective of the mission, which is to examine the remaining material of the formation of the Solar System, ca. 4.5 billion years ago As such, samples from the interior would be the most reliable source to discover what types of materials were present during the early Solar System.
By examining these materials, scientists seek to learn more about the key questions, from which water and organic materials are distributed throughout our Solar System. It is believed that this occurred during the Late Heavy Bombardment, approximately 4.1 to 3.8 billion years ago, and was intrinsic to the emergence of life on Earth.
By examining samples of asteroids dating from this period, scientists could also theorize with more confidence in what other part the materials necessary for life (as we know it) might have been distributed. And very soon, Hayabusa2 will provide us with some examples of evidence that will help answer these questions.
And to think that that was possible thanks to the same technology used to fly tanks! Meanwhile, the The spacecraft provides real-time images of the asteroid with the ONC-W1 camera. Once the scientific operations around the asteroid have been completed, the completion of which is scheduled for December 2019, it will return to Earth, scheduled for December 2020.
What we can learn from the samples you bring home will surely be exciting!
Additional readings: Reverse, JAXA