How the Mars rover landed

The rover named Perseverance landed on the surface of Mars. It is big, weighing about a ton, and since the atmosphere of Mars is so thin, parachutes are not sufficient to slow it enough to use airbags to cushion the final landing so they had to find another way.

Perseverance approached Mars at around 12,400 miles per hour, although when it hit the top of the atmosphere, a heatshield slowed it down to about a tenth of this speed. Then a supersonic parachute popped out of the rover to reduce its speed to a few hundred miles per hour.

At that point, descending under the parachute, Perseverance was still travelling far too fast to land safely. So it cut itself loose from the parachute and used rocket thrusters to slow down further. The thrusters allowed it to hover roughly 20 metres above the surface, before the rover was lowered by cables to the surface using a rocket platform called a sky crane.

Here is a video simulation of the landing.

You have to hand it to the engineers and scientists behind this project for a really impressive achievement.

You can see some of the first still images sent back here. There should be video soon too.

The consequences of the Republican-libertarian point of view

Texas is reeling from a severe winter storm that has resulted in huge swathes of the state being without power and caused 20 deaths so far.

Anger over Texas’s power grid failing in the face of a record winter freeze is mounting, as millions of residents remained shivering, with no assurances that their electricity and heat – out for 36 hours or longer in many homes – would return.
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Between 2 and 3 million customers in Texas still had no power, nearly two full days after historic snowfall and single-digit temperatures created a surge in demand for electricity to warm up homes unaccustomed to such extreme lows, buckling the state’s power grid and causing widespread blackouts. Meanwhile, people’s water pipes are bursting and hours long lines have been wrapping around grocery stores as people search for food.

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How the planets and moons got their names

I had not given much thought to how planets and moons were named. I just assumed that there was some scientific body that was authorized by the community of scientists to carry out this task. And while that is the case now, with the International Astronomical Union entrusted to do so, in the early days this naming process seems to have been quite ad hoc and a source of much controversy with egos, self-aggrandizement, and nationalist sentiment all playing roles.

Stephen Case, a historian of astronomy, explains how initially the planets in the Solar System got named after Roman gods but as the numbers of planets proliferated, disputes arose about who got the right to name them, with arguments being proffered for prioritizing the discoverers, starting with what we now know as Neptune. French astronomer Urbain Le Verrier, the person usually credited with that discovery, wanted to name it after himself and as part of his campaign, suggested that the planet we know as Uranus and that had been found earlier should be named Herschel after its discoverer, William Herschel. Herschel himself had named it Georgium Sidus after King George III, the king who had recently lost the British colonies in North America and is sometimes referred to as ‘Mad King George’.
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Postage stamp honoring C. S. Wu

If asked to name a famous female physicist, the name Marie Curie is the one most likely to come to mind. But there are many others and one of the people who should be much better known is Chien-Shiung Wu (1912-1997), who used to be often referred to as Madame Wu.

It was her careful experimental work that showed that parity violation did indeed occur, as predicted by theoretical physicists Chen Ning Yang and Tsung-Dao Lee. Yang and Lee received the Nobel prize for this in 1957 but Wu’s contribution was not recognized, an omission that has been widely criticized.

Wu was a remarkable physicist who did receive many other honors, as can be read in this biographical article. She was the first Chinese-American elected to the National Academy of Sciences in 1958 and in 1967 she served as the first female president of the American Physical Society.

Yesterday, on the occasion of the sixth International Day of Women and Girls in Science, the U.S. Postal Service issued a new forever stamp to honor her.

Cautious optimism about the pandemic

There is a glimmer of light in the pandemic darkness. The number of hospitalizations has been dropping and is close to half of what it was at its peak in early January. The number of deaths is also dropping.

But the current figures are still well above the previous peak values in the spring and summer of 2020.

We should also be concerned that people will take this news as license to let their guard down and that could cause yet another spike, which is what happened after numbers came down last summer.

Round two of my conflict with turkeys

Readers may recall my earlier close encounter with the wild turkeys that wander around the housing complex where I live. We could call that encounter a draw. But a couple of days ago, I had a rematch with one of them and this time the turkey was clearly the victor.

What happened was that I was going out somewhere and as I started driving on the road that exits the complex, I saw four turkeys ahead of me, straddling the road. I stopped to let them move on but turkeys are pretty casual about getting out of the way of cars and just hung around. After waiting some time, I drove around them but one of them took umbrage at this act of disrespect and chased after my car. I sped up and left it behind.
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Snake handling as a sign of faith

In general, the things that Jesus is reported to have said are fairly benign. (I do not want to get into the question of whether Jesus actually existed or said these things, which is something over which there is heated debate). But there is one thing that is highly problematic and that is found in the verses Mark 16:17-18 where, after his resurrection, he told his disciples the following:

“And these signs will accompany those who believe: In my name they will drive out demons; they will speak in new tongues; they will pick up snakes with their hands; and when they drink deadly poison, it will not hurt them at all; they will place their hands on sick people, and they will get well.”

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The anti-vaxxers seem to be more militant than the anti-choicers

We know that the anti-abortion crowd can be very militant and resort to extreme violence, to the extent of murdering people who provide abortion services. But I notice that recently anti-vaxxers seem to be approaching and even exceeding that level of fervor, as can be seen when protestors temporarily shut down a covid-19 mass vaccination site that had been opened in the Dodgers Stadium in Los Angeles.
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Super Bowl = Super Spreader

The encouraging news is that the number of covid-19 infections and hospitalizations in the US seem to have started to decline, though the death rates are still high. Since death rates is a lagging indicator by about two weeks, we can hope that they too will begin to decline soon. This graph shows how super spreader events like Thanksgiving and Christmas caused spikes that are only just abating.

By The New York Times | Sources: State and local health agencies and hospitals

But now there is another potential super spreader event and that is the Super Bowl to be held this Sunday. A poll suggests that 25% of all Americans will be “gathering with other people that live outside of your home (i.e., with people that are not roommates/cohabitants, etc.,) to watch the upcoming Super Bowl.” 64% said no and 11% said they don’t know or have no opinion.

25% of the population is a lot. While I can sort of understand how some people feel the pull of family gatherings at Thanksgiving and Christmas to be so strong as to overcome common sense advice to just stay at home, risking one’s life to attend a party to watch a sports event on TV seems truly idiotic, especially since only half watch it to see the game with the other half split between wanting to see the commercials and the half-time show, both of which can be easily seen later.