Six years ago, the Philae module of the Rosetta probe crashed on Comet 67P. It did not manage to fix itself in the programmed position, and after flying over it finally reached the bottom of the gully. But not long ago, it briefly landed for the second time in an area reminiscent of a human skull wearing a hat, leaving its mark on the ice billions of years ago. Now, the European Space Agency told it.
November 12, 2014 is a historic day for space exploration.This Lander Or “lander” Philae Free of probe Rosetta And drop to Comet 67P/ Churyumov-Gerasimenko. First, it bounced off the Agirquia area where the initial landing site was located, and then flew for two hours, during which time it collided with the edge of the cliff and crashed into the second landing site.
Soon thereafter, it finally stopped at the third and final landing site in the Abydos area, which was a concealed, barely exposed location. It was only a few weeks before the end of the mission, and it was not in Romania nearly two years later. Found in the image of Seta.
Laurence O’RourkeOne from European Space Agency (ESA) Played a key role in locating Philae, and then set out to find a mysterious second landing site.After a detective investigation, he succeeded, and now the results are published in the magazine natural.
He said: “Philae allowed us to solve the last problem.” “It is important to locate the landing site because Philae’s sensors indicate that it has penetrated the surface, which means it is likely to expose the original ice below. So that we can enter Billions of years of ice In ancient times, a priceless treasure”.
Register the mast in contact with ice
Together with a team of mission scientists and engineers, he set out to collect data from Rosetta and Philae instruments to locate and confirm the “lost” landing site.Although bright “cut ice” patches can be seen in the high-resolution image of the camera Osiris The location of Rosetta, the most important thing is to determine the location, this is the mast of the Gillea magnetometer, route map, This is the star of the show.
The instrument is designed to measure the magnetic field of the comet’s local environment, but for the new analysis, the team studied the changes recorded in the data captured when the mast protruding 48 cm above the module collided with some object and physically moved. surface.
When the mast moves relative to the lander’s body, the impact produces a series of characteristic peaks in the magnetic data, so that the duration of Philae’s contact with the ice can be estimated.This information is also used to limit acceleration Lander In these connections.
Compare ROMAP data with data captured by the magnetometer at the same time RPC Rosetta’s angle determines Philae’s inclination and excludes any influence from the magnetic field of the plasma environment around the comet.
“In 2014, we were unable to complete all the measurements arranged with Philae, so it is great to be able to use the magnetometer like this and combine Rosetta and Philae data in an unexpected way and get such excellent results. , ” He says. Philip Heinisch, He led the analysis of ROMAP data.
There are four contacts when logging in for the second time
The second analysis of landing data shows that Philae still maintains 2 minutes The flight was completed at the second landing site and at least four clear contacts were made while crawling across the ground.
When the top of Philae (Philae), a particularly eye-catching footprint is formed in the image Sink 25 cm into ice cubes On the side of the crack, obvious marks were left on the derrick and the side. Due to the movement of the mast, there was a spike in the magnetic field data, which indicated that Philae took three seconds to complete this particular depressing operation.
“From above, the shape of the rock hit by Philae reminds me of a skull (wearing a hat), so I decided to call the area”Skull“And continue to use this theme in the other forms we have observed,” Lawrence explained.
“The right eye of the skull is formed by compressing dust from the top of Philae, and the gap between the rocks is the gap between the skull, and the lander is like a windmill when it passes by.”
Analyze images and data from OSIRIS and spectrometers Vision de Rosetta confirms that the bright area is water ice, with an area of about 3.5 m2 pcs. Although most of the ice at the time of landing was in shadow, the images taken a few months later completely hit the sun, illuminating them like a lighthouse, and making them stand out from other surrounding objects.
This ice glows brighter than the surrounding material because it has never been exposed to the environment before and has not been affected by harsh space weather conditions. Lawrence pointed out: “It’s like a light in the dark.” He said that the distance from the surface of the comet to the last shot of Philae was only 30 m.
Snow and dust resemble the foam of cappuccino
In addition to the exciting conclusion of finding a second landing site, the study also provides the first measurement In situ The dust from the rocks in the comet and the smoothness of the ice inside.
The authors concluded that the force of ice on the rock is very low (less than 12 Pascals, which is softer than the light snow that has just fallen). In addition to the conclusion, their findings also provide information on the mechanical processes required to collect rock samples. . Ice, the future comet mission.
“The fact that Philae collided with the edge of the Rift Valley led us to conclude that the billion-year-old mixture of dust and ice is particularly softer and fluffy than the foam of cappuccino. A bubble bath or a wave breaking on the coast.” , Lawrence compares.
This research also makes it possible to calculate the porosity of the rock (the voids between the internal dust and ice particles) of about 75%, which is consistent with the value obtained by previous measurements of the entire comet. It also showed that the inside of the comet is uniform in size, up to one meter in height. This means that the rock represents the internal state of the comet some time before its formation. 4.5 billion years.
“This is an amazing multi-instrument result. It not only completes the story of Philae’s important events, but also informs the nature of the comet.” Matt Taylor, ESA’s Rosetta project scientist. “In particular, understanding the roughness of the comet is crucial for future landing missions. The softness of the inside of the comet is very valuable information when designing the landing mechanism and the mechanical process required to retrieve samples.”
How Philae left his mark on the second landing. / ESA etc.
O’Rourke et al. “The Philae Lander revealed low-strength primitive ice inside the comet boulder.” naturalOctober 28, 2020