Nasa space tests report large effects on Mars
Space probes have witnessed a big impact crater being formed on Mars - the largest in the Solar System ever caught in the act of excavation.
A van-sized object dug out a 150m-wide bowl on the Red Planet, hurling debris up to 35km (19 miles) away.
In more familiar terms, that\'s a crater roughly one-and-a-half times the size of London\'s Trafalgar Square.
And its blast zone would fit neatly in the area inside the UK capital\'s orbital motorway, the M25.
Scientists detected the event using the seismometer on the US space agency\'s InSight lander. The probe picked up the ground vibrations.
Confirmation came from follow-up imagery acquired by Nasa\'s Mars Reconnaissance Orbiter (MRO). This satellite routinely pictures the planet and could produce the before-and-after proof of a major surface disturbance, corresponding to the exact timing and in the expected direction and distance (3,500km) from InSight.
\"This is the biggest new crater we\'ve ever seen,\" said Dr Ingrid Daubar from Brown University. \"It\'s about 500ft wide, or about two city blocks across, and even though meteorites are hitting the planet all the time, this crater is more than 10 times larger than the typical new craters we see forming on Mars.
\"We thought a crater this size might form somewhere on the planet once every few decades, maybe once a generation, so it was very exciting to be able to witness this event.\"
The post-impact observation shows huge chunks of buried water-ice have been excavated and thrown around the edges of the crater. Buried water-ice has never before been seen so close to Mars\' equator.
Such deposits would be an important resource for future human missions to the planet.
\"That ice can be converted into water, oxygen or hydrogen. That could be really useful,\" said Dr Lori Glaze, Nasa\'s director of planetary science.
Using its French/UK-built seismometer instrument, Nasa\'s Insight lander has detected more than 1,300 quakes on Mars since its arrival in November 2018. But the Magnitude 4 tremor resulting from this particular event, which occurred on 24 December, 2021, immediately piqued the interest of mission scientists because it contained a component of so-called \"surface waves\".
The vast majority of quakes picked up by InSight have produced the traditional primary and secondary waves associated with rock movements deep within the planet.
These newly detected ripples were travelling in the uppermost portion of Mars, through its crust.