Martian meteorite Black Beauty landed on Earth after exploding from a strange crater
Black Beauty, also called NWA 7034, is among the most studied Martian meteorites. Its fragments were first discovered in 2011 in northern Africa. However, until now, scientists didn’t know anything about its origin. Now using machine learning, a team of researchers from Australia’s Curtin University has claimed to have pinpointed the exact location (on Mars) where the Black Beauty meteorite was born.
The researchers believe that their findings could play a crucial role in understanding the origin of Mars because the meteorite was formed in a region that also contains the oldest rock on the Red Planet. Mars is believed to have originated about 4.53 billion years ago, and surprisingly, one of the Black Beauty fragments is 4.48 billion years of age. Therefore, the place of its origin might unfold important details about the environment, geography, and landscape of early Mars.
So, where is Black Beauty’s home?
The total weight of Black Beauty is 320 gms. According to the researchers, to land on Earth, such meteorite needs to have an escape velocity of 5km/s (the escape velocity of Mars is about 5 km/sec). The collision that had provided Black Beauty with that much ejection speed at that time would have caused a crater of diameter three kilometers.
The researchers estimate that there are 90 million craters on Mars, and out of those over 80,000 craters have similar dimensions (3 km diameter). However, finding one crater (where Black Beauty originated) out of so many was a big challenge. To solve this seemingly impossible puzzle, the researchers at Curtin found and listed several characteristics.
For instance, since all Martian meteorites left their home planet not more than 20 million years ago, only the young craters that aged equal to or less than the same were candidates for Black Beauty’s home. Most of the three-kilometer craters didn’t fit this criterion, so they were automatically ruled out. The young craters were identified using thermal imaging by the presence of visible rays around them.
While explaining this further, lead author and research fellow at Cutlin University, Dr. Anthony Lagain told IE, “To know if a crater is fresh/young or not, one can look at the rays visible all-around a fresh crater using thermal infrared images. These rays are formed due to the blast of the impact and tend to disappear very quickly from the surface due to erosion and dust. If there are still visible today, this indicates that the crater is young.”
Another characteristic was that the home crater should be surrounded by some secondary craters. According to the researchers, multiple small craters would have formed from the debris of the high-impact collision that occurred at the time of Black Beauty’s ejection. However, even after considering different characteristics and using thermal imaging, scientists were left with numerous craters.
To pinpoint the exact crater, scientists further took the help of algorithms created using a powerful supercomputer named Pawsey. The algorithms shortlisted 19 Martian craters that could be considered as Black Beauty’s home. The researchers then compared the properties of the craters with those of the meteorite fragments on Earth and soon, they found the perfect match.
It was Karratha, a young Martian crater located in the Terra Cimmeria-Sirenum region of the Red Planet. Karratha is situated on an ancient crater named Khujirt. Interestingly, Karratha and Khujirt craters didn’t have any names before this study. The International Astronomical Union (IAU) named the craters after Earth’s Khujirt (in Mongolia) and Karratha (Australia) towns, respectively, as per the suggestions of Dr. Lagain and his team.
The significance of Black Beauty and its origin
Black Beauty is a special Martian meteorite because it comprises fragments of different types of Martian rocks. No other meteorite sample on Earth contains more than one type of Martian rock. So we’d have to wait at least eight years to bring more Martian rock and soil samples to Earth as the first proposed Mars Sample Return Mission is supposed to be completed by 2030.
Until then, Black Beauty is the perfect and only available brecciated specimen to understand the complex geology of the Red Planet. “Knowing the location of the origin of these unique samples is essential to get the geological context of their formation. If you do not know where these rocks are coming from, you cannot replace the results of the micro-scale analysis of the rocks in a broader context and get a global vision of the planet's (Mars) evolution,” said Dr. Lagain.
The study is published in the journal Nature Communications.