Why the Parker Solar Probe is NASA's most exciting mission
Dr. Michelle Thaller is an astronomer who studies binary stars and the life cycles of stars. She is Assistant Director of Science Communication at NASA. She went to college at Harvard University, completed a post-doctoral research fellowship at the California Institute of Technology (Caltech) in Pasadena, Calif. then started working for the Jet Propulsion Laboratory's (JPL) Spitzer Space Telescope. After a hugely successful mission, she moved on to NASA's Goddard Space Flight Center (GSFC), in the Washington D.C. area. In her off-hours often puts on about 30lbs of Elizabethan garb and performs intricate Renaissance dances. For more information, visit NASA.
Michelle Thaller: One of the most exciting things that's going on at NASA right now is that we have a probe that's actually orbiting very close to the sun. And over the next years, it's going to get closer, and closer, and closer. It's called the Parker Solar Probe, and the catch phrase, sort of the mission motto is, a mission to touch the sun. And that sounds incredibly dramatic. I should probably quantify that a bit. We're not actually touching the surface of the Sun, but the Sun has an atmosphere of gas around it, almost like the Earth has an atmosphere. It's called the corona. And the corona extends many millions of miles away from the surface of the Sun. Parker Solar Probe is actually going to fly through the Corona, getting into a fairly close part.
Now, it doesn't sound so close. It's going to get within about four million miles away from the Sun. But the Sun itself is nearly a million miles across. It's about 900,000 miles across. So this is actually getting just about four times the diameter of the Sun away, which is really pretty close. It's by far the closest object that humanity has ever sent to the Sun.
Over the next seven years, it's going to orbit around 24 times. And each time, it's going to get a little bit closer to the Sun. And in order to survive that, in order to have enough speed to actually escape the Sun's gravity and come out again, it's going to go faster and faster all the time as well. So at its fastest-- in a few years from now-- the Parker Solar Probe will be going nearly 400,000 miles an hour as it loops around the sun and then comes right back out again. That's by far the fastest speed that any human-made spacecraft has ever attained. And that's going to be very exciting. So each perihelion is a little closer and a little faster, and then the orbit takes it out close to the planet Venus. And the planet Venus actually-- interestingly enough-- it helps Parker lose energy. In order to get closer and closer to the Sun, Parker has to lose some of its own rotational energy. And when it loses energy, it can drop in a little closer all the time. So over the next years, you're going to see our spacecraft get a little closer each time and go a little faster each time it goes around the Sun.
Now, what are we looking for? Why are we actually flying a spacecraft this close to the Sun? Well, the corona, the atmosphere around the sun, is actually one of the biggest mysteries in our solar system. It's extremely hot. The gas around the Sun is millions of degrees. And that's rather strange because the surface of the Sun itself is only about 10,000 degrees. So how can the gas above the surface be that much hotter than the surface itself? Kind of the analogy we use at NASA is picture yourself around a campfire at night and you're enjoying the warmth of the campfire, but then as you walk away from the fire, it becomes hotter and hotter as you go away and burns you to a crisp five miles out. That doesn't work. It's a very strange way of thinking about temperature. So something's going on with the corona. It may have to do with the Sun's complex magnetic field. Maybe the magnetic field is shooting particles up into it. It may have to do with shock waves, even the Sun vibrating and actually giving energy to the gas above it. There's many different ideas and theories as to why the corona is so hot. But right now, we don't have a great way to tell which is right and which isn't. So when we're there and actually measuring how fast the particles are going, the different particles you find, how dense or how rarified that gas is around the sun, we'll have a much better idea which of those theories are true.
The Parker Solar Probe to me is also a marvel of modern engineering. I mean, think about how are you going to get a spacecraft that close to the Sun, and have it survive and not burn up. Well, the whole spaceship is protected by a heat shield. The heat shield itself is not very thick. It's actually only about six inches thick. And it's made of a carbon composite material with a very shiny reflective aluminum coating on top. Incredibly, that heat shield is still going to get up to about 2,500 degrees Fahrenheit. So it's going to get very, very hot, but that will protect the rest of the spacecraft from the radiation coming from the Sun. And the angle has to be just right. You always have to have the heat shield right in between the Sun and the rest of the spacecraft. The rest of the spacecraft has to be in its shadow, or it will fry. And we actually can't send commands up to Parker often enough to make sure it's exactly lined up. So Parker is a very autonomous spacecraft. It's constantly detecting what its angle is relative to the Sun and correcting that. So in some ways, it's one of the most autonomous spacecraft yet launched.
One of the things I think is kind of funny about the design is it does use solar power-- that makes sense-- you're very close to the Sun. But it has these really, really dinky little solar panels off to the side because when you get close to the sun, you don't need big solar panels. So at the end of Parker Solar Probe's mission, we will have this thing orbiting closer to the sun than we've ever been before, going faster than we ever have before. And maybe we'll finally have some idea why this corona, this mysterious million-degree gas around the Sun can possibly be that hot.
- The Parker Solar Probe is set to uncover a mystery about the sun: Why is it's corona hotter than its surface?
- NASA's ability to fly a probe so close to the sun is a marvel of engineering.
- Michelle Thaller, an astronomer at NASA, explains why the Parker Solar Probe is so hot right now.
Researchers hope the technology will further our understanding of the brain, but lawmakers may not be ready for the ethical challenges.
- Researchers at the Yale School of Medicine successfully restored some functions to pig brains that had been dead for hours.
- They hope the technology will advance our understanding of the brain, potentially developing new treatments for debilitating diseases and disorders.
- The research raises many ethical questions and puts to the test our current understanding of death.
The image of an undead brain coming back to live again is the stuff of science fiction. Not just any science fiction, specifically B-grade sci fi. What instantly springs to mind is the black-and-white horrors of films like Fiend Without a Face. Bad acting. Plastic monstrosities. Visible strings. And a spinal cord that, for some reason, is also a tentacle?
But like any good science fiction, it's only a matter of time before some manner of it seeps into our reality. This week's Nature published the findings of researchers who managed to restore function to pigs' brains that were clinically dead. At least, what we once thought of as dead.
What's dead may never die, it seems
The researchers did not hail from House Greyjoy — "What is dead may never die" — but came largely from the Yale School of Medicine. They connected 32 pig brains to a system called BrainEx. BrainEx is an artificial perfusion system — that is, a system that takes over the functions normally regulated by the organ. Think a dialysis machine for the mind. The pigs had been killed four hours earlier at a U.S. Department of Agriculture slaughterhouse; their brains completely removed from the skulls.
BrainEx pumped an experiment solution into the brain that essentially mimic blood flow. It brought oxygen and nutrients to the tissues, giving brain cells the resources to begin many normal functions. The cells began consuming and metabolizing sugars. The brains' immune systems kicked in. Neuron samples could carry an electrical signal. Some brain cells even responded to drugs.
The researchers have managed to keep some brains alive for up to 36 hours, and currently do not know if BrainEx can have sustained the brains longer. "It is conceivable we are just preventing the inevitable, and the brain won't be able to recover," said Nenad Sestan, Yale neuroscientist and the lead researcher.
As a control, other brains received either a fake solution or no solution at all. None revived brain activity and deteriorated as normal.
The researchers hope the technology can enhance our ability to study the brain and its cellular functions. One of the main avenues of such studies would be brain disorders and diseases. This could point the way to developing new of treatments for the likes of brain injuries, Alzheimer's, Huntington's, and neurodegenerative conditions.
"This is an extraordinary and very promising breakthrough for neuroscience. It immediately offers a much better model for studying the human brain, which is extraordinarily important, given the vast amount of human suffering from diseases of the mind [and] brain," Nita Farahany, the bioethicists at the Duke University School of Law who wrote the study's commentary, told National Geographic.
An ethical gray matter
Before anyone gets an Island of Dr. Moreau vibe, it's worth noting that the brains did not approach neural activity anywhere near consciousness.
The BrainEx solution contained chemicals that prevented neurons from firing. To be extra cautious, the researchers also monitored the brains for any such activity and were prepared to administer an anesthetic should they have seen signs of consciousness.
Even so, the research signals a massive debate to come regarding medical ethics and our definition of death.
Most countries define death, clinically speaking, as the irreversible loss of brain or circulatory function. This definition was already at odds with some folk- and value-centric understandings, but where do we go if it becomes possible to reverse clinical death with artificial perfusion?
"This is wild," Jonathan Moreno, a bioethicist at the University of Pennsylvania, told the New York Times. "If ever there was an issue that merited big public deliberation on the ethics of science and medicine, this is one."
One possible consequence involves organ donations. Some European countries require emergency responders to use a process that preserves organs when they cannot resuscitate a person. They continue to pump blood throughout the body, but use a "thoracic aortic occlusion balloon" to prevent that blood from reaching the brain.
The system is already controversial because it raises concerns about what caused the patient's death. But what happens when brain death becomes readily reversible? Stuart Younger, a bioethicist at Case Western Reserve University, told Nature that if BrainEx were to become widely available, it could shrink the pool of eligible donors.
"There's a potential conflict here between the interests of potential donors — who might not even be donors — and people who are waiting for organs," he said.
It will be a while before such experiments go anywhere near human subjects. A more immediate ethical question relates to how such experiments harm animal subjects.
Ethical review boards evaluate research protocols and can reject any that causes undue pain, suffering, or distress. Since dead animals feel no pain, suffer no trauma, they are typically approved as subjects. But how do such boards make a judgement regarding the suffering of a "cellularly active" brain? The distress of a partially alive brain?
The dilemma is unprecedented.
Setting new boundaries
Another science fiction story that comes to mind when discussing this story is, of course, Frankenstein. As Farahany told National Geographic: "It is definitely has [sic] a good science-fiction element to it, and it is restoring cellular function where we previously thought impossible. But to have Frankenstein, you need some degree of consciousness, some 'there' there. [The researchers] did not recover any form of consciousness in this study, and it is still unclear if we ever could. But we are one step closer to that possibility."
She's right. The researchers undertook their research for the betterment of humanity, and we may one day reap some unimaginable medical benefits from it. The ethical questions, however, remain as unsettling as the stories they remind us of.
Can you make solar power work when the sun goes down? You can, and Dubai is about to run a city that way.
- A new concentrated solar plant is under construction in Dubai.
- When it opens next year, it will be the largest plant of its kind on Earth.
- Concentrated solar power solves the problem of how to store electricity in ways that solar pannels cannot.
Believe it or not, for a few decades, giving people "milk transfusions" was all the rage.
- Prior to the discovery of blood types in 1901, giving people blood transfusions was a risky procedure.
- In order to get around the need to transfuse others with blood, some doctors resorted to using a blood substitute: Milk.
- It went pretty much how you would expect it to.
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