Well, while we wait for good early morning comet observing opportunities, we return to masks and asymptomatic spread of COVID-19 and shutdown of some restaurants, and finish up with some comments from NASA online Lunar Science Workshop.
So, Comet C/2020 F3 (NEOWISE) is projected to be very bright, magnitude <1.6, in the next couple of weeks, so get your coffee and get out there before sunrise and take your photos. In the meantime, we headed off to one of our favorite dining spots and were worried that the recent shutdown order of dine-in seating might affect us, but, no, sit down dining was still available on the open-air patios. In addition, you can see that many restaurants are busy adding additional sit-down dining in their parking lots.
|High Park Tap House, augments patio seating with parking lot dining (Source: Palmia Observatory)|
So, what is going on that requires shutdown again of dine-in seating? The existing COVID-19 Industry Guidance for Dine-in Restaurants of July 2, sets the requirements. The guidelines include physical distancing, cleaning, masking of restaurant personnel and in-door air quality requirements. My sense of the big worry for COVID-19 risk was the in-door air quality due to trapping and re-circulation of air that might include viral particles. Most commercial building air conditioning systems include some level of air re-circulation as an energy saving method.
Diners are not required to wear masks and if any of them are shedding viruses in their breath, then in enclosed spaces the level of viral particles can increase. This difference then seems to explain why dining outside, on open patios for example, are safer for participants.
|California COVID-19 Guidance for Dine-in Restaurants (www.covid19.ca.gov)|
We know to maintain distance from infected individuals, but now we must include the asymptomatic person, who displays no symptoms, but still sheds viruses, into our risk calculation. We want to go out but we want to understand the risks. This week of Science reviewed how masks make improvement in risk reduction for this asymptomatic case. The amount of virus particles directed towards others with just normal breathing is deflected and reduced.
|Masks reduce airborne transmission (Source: K. Prather, et al, Science, June 26, 2020)|
So now our risk modelling has to include two different classes of asymptomatic infected persons. First are those who are infected, but not yet showing symptoms, who will later on begin showing symptoms. So there were will a period of some duration when they can infect others and at the same time not have any special concerns because they don't recognize they are sick. The other class of infected are those who never display any symptoms and yet can infect others. So, the duration of time in which both classes can infect others increases the risk to the rest of us of contracting the disease. How long both classes are contagious depends on their immune system response. But again, wearing of masks by the asymptomatic, which really translates into all of us wearing masks, is a key risk reduction strategy.
Now in this article from Medical News Today we see that some estimates put the number of asymptomatic people at about 50% of the total that contract the disease. Ouch, these silent spreaders, which could be anyone of us, is of real concern.
|Getting better estimates of asymptomatic spreaders is key (Source: MedicalNewsToday)|
By the way, if you want to follow a weekly discussion between a bunch of virology professors and practictioners in the field, you might want to sit in on the "This Week in Virology (TWiV" podcasts provided by Professor Vincent Racaniello of Columbia U. I started listening to his virology class way back in March and have sort of been somewhat hooked since then. He has discussions with the experts and guest interviewees from various hospitals around the country. They talk and discuss and answer email from the listeners. It is a pretty good source of ongoing developments in the virology science.
|This Week in Virology (TWiV) is good podcast resource (Source: https://www.microbe.tv/twiv/)|
Professor Racaniello mentioned that another Columbia virology professor, Raul Rabadan, had just released a new book on the coronavirus. It turns out that Rabadan was on sabbatical and had hoped to visit and work with other colleagues, but because of the shutdown, he was sequestered in his apartment and elected to right then and there write this new virology book "Understanding Coronavirus."
I found the book on Amazon for about $10 in the e-book version. This book is quite complete but does not go into any details. If you want the technical details and have a desire to slog through a lot of the microbiology, then get Professor Racaniello's or others' virology textbooks. If you are not serious about virology you will regret getting one of those very technical textbooks.
By the way, there are dozens of other books already written about coronavirus. Most of them are on how to explain the topic to children or how to handle the anxiety and worry and how various religions try to explain what is happening. I had no idea the bookshelves would already be full of books like that.
|Search for "Coronavirus" on Amazon finds a diverse lot of books (Source: Amazon)|
Ok, so even though we have all been preoccupied with the state of our COVID-19 pandemic world, we did finally manage to get online for the NASA Lunar Science Workshop, July 8-10, 2020, and can make a couple of comments now, maybe more later. Many sessions covered the ongoing science and investigations lunar science and where the water can hopefully be found. I had forgotten that the Lunar Reconnaissance Orbiter (LRO) was still in orbit and operating around the Moon. Going on 11+ years now. Pretty neat!
|LRO still going 11+ years (Source: Noah at NASA Lunar Science Workshop, 2020)|
Another interesting presentation that caught my attention was the NASA Double Asteroid Redirection Test (DART) mission. DART is a planetary protection test of key technologies needed to intercept a near Earth asteroid that could collide with the Earth. A new camera (DRACO) and ion-thrust engine (NEXT-C) and Roll Out Solar Arrays (ROSA). Wow, take a look at how the roll out solar panels extends out 60 feet.
DART test will intercept the small binary asteroid, Didymos, and close in on it with ion thrusters and new terminal guidance algorithms and intercept the smaller of the binary pair. This collision will change the pairs orbital timing, which can be observed and measured from Earth. The goal is to verify that the whole mission concept can intercept a NEA and effect a predicted change in its orbit. Then for real planetary defense mission, we can rely on the proven technology to change the orbit in just the right way to avoid a collision with Earth. Wow, hope it proves it can work!
|Testing new technologies for planetary defense (Source: E. Adams, NASA Lunar Science Workshop)|
Another great presentation described the effects from landers landing and taking off from the Moon. It seems that the rocket exhaust launches many tons, many more that the weight of the lander, into space. The low Moon gravity and no atmosphere means that these tons of debris are launched into orbit and only after months do they settle back down on the moon. This debris is travelling and moving with hyper-velocity and can cause damage to orbiting spacecraft or other structures on the surface. Wow, I had no idea about this effect! When craft are coming and going a lot in the future exploration of the Moon, who knows what the risk and effects will actually be!
Finally, we transitioned to fun presentations, without discussion of more risks and anxiety, but of beauty and photos of the Earth and Moon as a unit. I only show a couple of the photos provided by Professor Carle PIeters, Brown U. Check out this first photo of the Earth and Moon taken by the Voyager 1 spacecraft. Neat! I would have guessed that one of the early crewed missions would have taken the first such photo but apparently not.
Another selection, out of many, is this next photo taken by the Solar Dynamics Observatory (SDO) and it was one of my favorites. Here you can see the Sun and the Moon and the Earth all lined up. The Sun shows up with its surface corona and the Earth, because of its atmosphere, does not cast a sharp shadow. The Moon on the other hand displays a crisp clear edge. Pretty neat; thank you for that Carle!
Until next time, here from our burrow, stay safe, as we recover more of our freedom,
Resident Astronomer George
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