Ask an Asteroid Scientist


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Ask an Asteroid Scientist

Unread postby Lloyd » Mon Nov 13, 2017 11:53 am

A family friend is now an asteroid scientist. If anyone has questions for him, let me know. Below are questions I asked him and his answers. I'll try to see if he'll be at all open to any EU concepts. It doesn't look promising.

Astrophysics etc
Sunday, November 12, 2017 1:50 AM
From: "John Weirich"

>LK: When did you graduate from college and in what fields mainly?
_John: I have a B.S. in Physics from the University of Missouri at Rolla (now called the Missouri School of Science and Technology), 2001. I have a PhD in Planetary Science from the University of Arizona, 2011.

>LK: What jobs/positions have you had after college?
_John: After I finished my PhD I was at Arizona State University. My position was a post-doctoral researcher working on Apollo 17 samples.
_My next position was in London, Ontario, Canada. At Western University also as a post-doctoral researcher, working on the Sudbury Impact crater.

>LK: When did you get your present position with NASA?
Or do you work for a company that contracts with NASA?

_John: I started on the OSIRIS-REx project in June of 2015. I work for the Planetary Science Institute (PSI for short) in Tucson, AZ. I do not work for NASA, but at PSI roughly 98% of that funding comes from NASA.

>LK: Have you ever been a teacher or had interest in it? You seem to like to share knowledge.
_John: I did teach a class when I was at Western University in Canada. I may teach again in the future, but teaching jobs are a bit hard to come by. Currently the US is producing more PhDs than the universities can hire. Back in the 70’s about 50% of PhD’s went into teaching and the rest went into research. Now it’s more like 10% in teaching.

>LK: Did you say you're more a geologist than an astronomer?
_John: I’m probably closer to geology than astronomy, but I’m a bit of everything. Planetary Science is a very wide field that includes Physics, Geology, Chemistry, Astronomy, and a bit of Biology and Math, though the Biology is a fairly small part.

>LK: What's your project mission with asteroid Benu again?
_John: I’m working on the OSIRIS-REx project which is going to bring back surface material of asteroid Bennu. My specific part is building the global Digital Terrain Model of Bennu, which is just a fancy way of saying a 3D model.

>LK: If your team strikes gold there, or some other precious metal, will you stake a claim?
_John: There is no legal precedence for staking claims on extra-teriterristal objects. I doubt we’ll find much at Bennu worth mining, but who knows? The main thrust for the OSIRIS-REx mission is to bring back a sample so we can understand how to turn telescope data into enough information to determine how much an asteroid would be worth. The idea is that Bennu will tell us “This telescope signal means Bennu has this (probably small) amount of precious metals. But the telescope signal from this other asteroid is 1000 times larger than on Bennu, so it has (a reasonable amount) of precious metals."

>LK: Do you know if asteroids, comets and/or spacecraft get ionized in space?
_John: Large objects don’t get ionized, but the molecules and elements in them can get ionized. The amount of mass that gets ionized is tiny; it’s usually a tiny fraction of the atmosphere, or if it’s an airless body then a tiny fraction of the surface (micrometers to millimeters thick, probably more like micrometers). However these ions are easy to detect with telescopes and other instruments on spacecraft. Ionized molecules make interesting chemical reactions with other molecules and some people make entire careers out of analyzing the chemistry that occurs on these objects. Pretty much anything exposed to direct solar rays or cosmic rays (rays from outside the solar system) can be ionized, including the very outer portions on spacecraft. As long as you have a little bit of mass between you and the rays then nothing affect[s] you. Our atmosphere does a great job of blocking ionizing radiation.

>LK: If they do [get ionized], do you have to take their charges into account when bringing them close together?
_John: If you’re talking about molecules interacting with each other then the charge is important, but for entire objects it won’t matter. Keep in mind that even though the atmosphere/surface becomes ionized, overall the atmosphere/surface remains neutral. For example, if a pool of water became ionized, the H-O-H (H2O) bonds would break into H+ and OH- ions, but the charge of the pool of water would stay neutral because for every positive ion there would be a negative ion. The distance required for the charge to become important is quite small, less than micrometers.

>LK: Do spacecraft have to take into account the charge of Earth's ionosphere when returning to Earth?
_John: Not to determine the path of the spacecraft. There might be some interesting chemistry that occurs on the surface of the spacecraft, but the heat shield would protect the rest of the spacecraft from the ionizing radiation.

>LK: Are meteors charged much when they enter Earth's atmosphere?
_John: They’re not charged, but the friction between the atmosphere and surface of the meteorite heats it up and causes what the planetary science community calls “fusion crust.” It’s sort of a black glassy rind on the meteorite.

>LK: Does the solar wind tend to charge objects that encounter it? I understand the solar wind is weak beyond Earth's orbit. Right?
_John: The solar wind doesn’t charge the object that it hits, but again it does cause some interesting chemistry. For what it’s worth, the solar wind is ionized, but overall neutral. Unlike the H+ OH- example I gave above, the solar wind is mostly H+ and electrons, with a small amount of He+ (helium) and a tiny fraction of everything else. The further you get from the sun the less dense the solar wind becomes, so while it’s weaker beyond Earth’s orbit it can still drive important chemistry.

>LK: Charles Chandler found that the Titius-Bode Law is explainable as repulsion between charged planets, just like plasma cells in the lab. Comment?
_John: The Titus-Bode Law was an early “predictor” of planet positions, but it wasn’t based on physics. From my understanding of it, it was more of a “Hey we noticed that if you plug the known planet positions into this (mostly made up but simple) equation everything kinda fits.” And the “kinda fits” is being generous. I’m not familiar with repulsion between plasma cells in the lab. I don’t know of a way to charge up the planets, but if there was some mechanism I would actually think the solar wind would neutralize it. The solar wind is neutral when it leaves the Sun, so if it encountered a charged object, that object would repulse the similar charged particles, and the opposite charge particles would react with the object and neutralize the object. I don’t really spend much time thinking about the solar wind, so I could be off base, but applying what I know about physics and chemistry that would be the outcome.

>LK: What are the large and small diameters of Benu again?
_John: It’s about 510 meters pole to pole, and 565 meters for the long axis. The third axis is 535 meters. So it’s not a squashed ball like Earth where the equator everywhere has the same diameter. With these small objects they can get to be pretty non-spherical.

>LK: I think you said it's a NEA, or near-Earth asteroid. Right?
_John: Yep!

>LK: Is it like a moon or satellite of Earth, or is it like a Trojan, or is it just in a similar orbit at ca. 1 AU?
_John: The NEAs are all in orbit around the Sun. I poked around on google and found this pic showing Bennu’s orbit. If you’re not familiar with these pictures, you’re basically looking down on the north pole of the Earth and the Sun, the dotted lines show the paths of the objects (well the spacecraft is solid), and if I understand the picture correctly, this will be the position of the objects in August of next year.

>LK: Can you describe the tech you use again? I think you said you do mapping that gets adjusted/fine-tuned as you approach Benu. Right?
_John: Yep! In short we take the 2D images we get from the cameras, and using the known position and pointing of the spacecraft at the time each image was taken we can recreate the 3D shape of the object. As the mission progresses we get higher and higher resolution images, so the 3D shape gets better and better. It has to be done incrementally.

>LK: Did you say you've worked with 3D printing, or have seen it? Or with AI?
_John: Much to my surprise 3D printing isn’t really that expensive from a business perspective. The mission bought one to print off objects for public outreach events.
_I haven’t used AI. We do use pattern matching routines with our software, but it’s not learning anything. That part of the software just takes two images and lines them up, somewhat like photoshop can make a panoramic image from a series of pictures.

>LK: What kinds of tech do you enjoy the most? What's so great about them?
_John: Not sure what scope or range you’re looking for here, could you give more details? I have a smart phone that I think is pretty cool, but I don’t think that’s what you mean! :)

>LK: Did you get into science in order to avoid hard work and make easy money?
_John: I got into science because I enjoyed it and was good at it. Most people in science, and especially the prominent ones in the field, put in 50-60+ hours a week. The pay check is decent, but I actually gave up money to do this type of work. I almost went into Engineering instead of Science. Engineers are paid way more than scientists, and most of them don’t have PhDs! Engineers work hard too, but they get paid more for the same amount of work.

>LK: To graduate from college, do they make sure you believe in relativity, quantum mechanics, the big bang etc first?
_John: Well they have exams where they make sure you can do the math and understand the concepts taught in the class. They don’t grill you to make sure you “believe” in science. The thing about science, and physics in particular, is that everything is based on something that can be measured. And anybody with the proper equipment can measure it. But a theory isn’t accepted until it makes predictions that turn out to be correct. I never had any outward pressure to “believe” in any of the theories. It was my own pursuit of the theories, reading about how the theories were developed and tested, and which of the observations that were predicted to occur and why. If you compare current theories to the abandoned theories (and importantly why those old theories existed in the first place) it actually strengthens the current ones. Germ theory (bacteria and viruses as the source of disease) was meet with massive resistance by the medial community when the ideas were being developed. Now 5th graders look at bacteria under microscopes and we go get antibiotics every time our throat is scratchy.
_I should mention that the media doesn’t do a good job of accurately portraying scientists and religious beliefs. They tend to latch onto people like Stephen Hawking who are prominent atheists. Of the professors at the department I earned my PhD, I would say 30-40% of them were religious. That's less than the general population, but the media makes it seem like there’s only 1 or 2 per university. I imagine you’ve never heard of him, but Guy Consolmagno is a Jesuit Brother, prominent in my field, and received his PhD from the department I went to, and frequently visits PSI to collaborate with colleges; he’s also the director of the Vatican Observatory and was appointed by the Pope. He has a wikipedia page here if you’re interested.

>LK: Would it be possible to fake the Moon landings or the Mars rovers etc?
_John: For the Moon landings: If it was just camera footage that everyone has seen, possibly. But the radio signals transmitting the data was coming from the Moon, and if the Russians found the radio signals were coming from Earth they would have called shenanigans. The other things is we brought Moon rocks back, as did the Russians with their unmanned “Luna” missions. Scientists worldwide have looked at both samples, and agree that they are similar to each other, and very different from Earth rocks or meteorites. In the 70’s Russia was more motived to uncover a hoax than people are today!
_For the Mars rovers: Same thing about the radio signals from Mars.
_Also for both: Given the large quantities of data that come from these missions, it would actually be harder to generate all that data and have it make sense, than it would be to just build the spacecraft and send it there.
_There’s also this comic from a few years ago. Moon Landing

>LK: Would you be interested in spaceflight? _John: If the risks were extremely low?
_John: Once many others have done it and the cost came down I’d be interested. Back in 2012 Virgina Galactic was taking reservations on a future flight for something like $300,000-500,000. They haven’t launched anything yet, and I don’t know if they’re still even taking reservations, but if I had that kind of money in the bank I think I’d rather buy a nice house, or just leave it for retirement!

>LK: Do you expect humans to go to Mars? If so, when?
_John: I think we’ll get there eventually, but I don’t know about it in my lifetime. If you look at when NASA thinks we’ll put people on Mars, it’s always about 20 years in the future. After Apollo 17 it was in 20 years, around 2000 it was in 20 years, right now NASA says… about 20 years. So who knows.

>LK: What city do you work in?
_John: PSI has 100+ scientists who live all over the world, but about 1/3 of us (including me) are in Tucson, AZ.

>LK: May I ask more questions for follow-up after you reply (soon)?
_John: Sure, but it may take awhile for me to find time. This was suppose to be a somewhat quick email, but apparently I can’t give short answers!
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