Finding evidence of a stream bed on Mars

Ken Tapping's weekly astrophysics column from the DRAO Herzberg Institute

 

 

At first, the image did not look very impressive. It showed a piece of rock sticking out of sandy, gravelly soil. The rock itself, reddish, like its surroundings, consisted of rounded pebbles cemented together by some much finer stuff. This kind of rock is called conglomerate, but quarrymen often refer to it as “pudding stone”, because it looks like a plum pudding. This particular specimen was especially generous with the plums.

Things get more intriguing as we look more closely. The pebbles are all nicely rounded, like the ones we find at the bottom of streams and on old stream beds. If you bash two pieces of rock together, you’ll get some dust and a jagged fragment or two. If you want to try this, wear gloves and eye protection.  Proper footwear would not hurt as well. Dropped rocks have a magical property that makes them home onto feet.

Rock fragments start off as jagged bits. They get turned into rounded pebbles by flowing water. They get rolled along, abraded by sand and collide with other rocks. The result is nicely rounded and often polished pebbles. Looking even more closely at the image shows not all the pebbles are the same kind or rock. There are contributions from a number of different rock outcrops. They were all picked up, rounded and rolled to a new location kilometres away by flowing water. We see this in almost any stream bed.  Then, as the layer of pebbles builds up, silt settles in the cracks, where the current cannot wash it way, until over millions of years it consolidates into the pudding stone we see today.

So our rock outcrop says that long ago, a fairly brisk stream flowed through that location, possibly billions of years ago, and what we see today is a reminder of that ancient stream. What sort of terrain did it flow through? Were there living creatures in it? What makes this particular stream interesting is that it flowed on Mars, and the image was sent back by the Curiosity rover.

Pictures taken from Mars Reconnaissance Orbiter, a spacecraft surveying the Red Planet from above, show that Curiosity landed near a stream that once flowed down from nearby high ground. As it reached the bottom of the grade and slowed, it made a huge fan of dropped material.

Some knowledge of geology and physical geography help us to understand the landscape around us, and the forces that made it as we see it today. The features we see might individually seem commonplace and everyday, but the story they tell us is anything but that.

Now we are seeing that although Mars has been a frozen, almost airless and unbelievably dry place for many millions of years, once, long ago, it was not like that at all. There was a denser atmosphere, it was warmer, due to the greenhouse effect, and there were lakes and rivers, even seas, which meant it must also have rained. Were there living things on Mars’ surface back then? Why did it all go wrong on Mars, but not for us here on Earth? It would be very useful to know that!

Mars is low in the Southwest after sunset. Jupiter rises around 9 p.m. and Venus around 5 a.m. The Moon will be full on the 29th.

Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astro-physical Observatory, Penticton.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Just Posted

‘His kids were No. 1’: Wife remembers man shot dead in Kamloops

Wife of Kamloops shooting victim describes him as loving, hardworking family man

Summerland to host fourth annual Grand Sommelier Express

Wine event will be held on Kettle Valley Steam Railway’s historic train

Okanagan OneWorld Festival brings cultures together

The annual SOICS event returns Feb. 23 to the Lakeside Resort

Penticton woman captures footage of bobcat feasting on bird in backyard

‘Kim Ken Oszinski’ posted photos and videos of the bobcat from just a few feet away

Okanagan Shuswap weather: Glimpses of sun expected on another wintry day

The sun will be peeking out from behind the clouds for the next few days

5 Events to check out at local ski hills

Check out this new column from Okanagan events guru Christina Ferreira

New report calls for regulated heroin sales to curb B.C.’s overdose problem

B.C. Centre on Substance Use points to organized crime and money-laundering as contributing factors

Millennial men least likely to have a family doctor: Statistics Canada

Report found more women have primary care physicians, compared with men

Okanagan man fined $600 for twenty-third illegal driving conviction

Judge says another offense could result in jail time

Snowplow accident leads to power surge, small claims decision

Tribunal rules Shuswap resident not entitled to additional compensation

70% of Canadians agree with mandatory vaccines for children: poll

The debate for pro and anti vaccinations has heated up after a measles outbreak in Vancouver

VIDEO: Woman, off-duty cop in serious condition after stabbing outside B.C. elementary school

The officer was interceding in an alleged assault when he and the woman were stabbed

Most Read