venerdì, Novembre 27, 2020
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Space life : radiation and the effects of microgravity could damege your body and fry your electronics devices

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NASA astronaut Don Pettit holds a ThinkPad at the International Space Station during Expedition 30. Before sending personal electronic devices to space, NASA tests them to make sure they can withstand the high levels of radiation out there. Credit: NASA
While space radiation research has expanded rapidly in recent years, large uncertainties remain in predicting and extrapolating biological responses to radiation exposure in humans.
As future missions explore outside of low-Earth orbit (LEO) and away from the protection of the Earth’s magnetic shielding, the nature of the radiation exposures that astronauts encounter will include higher radiation exposures than any experienced in historical human spaceflight.
The study of human health risks of spaceflight (e.g., bone health, behavior, nutrition, etc.) typically involves analogs that closely represent the space environment.
In most cases, theory, models, and study outcomes can be validated with available spaceflight data or, at a minimum, observation of humans subjected to analog terrestrial stresses.
In contrast, space radiation research is limited to the use of analogs or models that for many reasons do not accurately represent the operational space radiation environment or the complexity of human physiology.
For example, studies on the effects of space radiation generally use mono-energetic beams and acute, single-ion exposures (including protons, lithium, carbon, oxygen, silicon, iron, etc.) instead of the complex energy spectra and diverse ionic composition of the space radiation environment.
In addition, a projected, cumulative mission dose is often delivered in one-time, or rapid and sequential, doses delivered to experimental animals.
In most cases, these dose-rates are several orders of magnitude higher than actual space environment exposures.
Even the use of animal models introduces error, as studies make use of a variety of animal species with differing responses and sensitivity to radiation that may not represent human responses to similar exposures.
Further, studies do not challenge multiple organ systems to respond concurrently to the numerous stressors seen in an operational spaceflight scenario. Historical epidemiological studies of humans, which are generally used for correlation of animal and experimental models, include populations such as atomic bomb or nuclear accident survivors exposed to whole-body irradiation at high doses and high dose-rates, limited to scenarios not found in spaceflight.
These disparities and numerous other environmental considerations contribute to the large uncertainties in the outcomes of space radiobiology studies and the applicability of such studies for extrapolation and prediction of clinical health outcomes in future spaceflight crews.

Biological stressors related to space radiation are due to the effects of energy transfer from a charged particle to the human body.

The combination of a particle’s charge, mass, and energy determines how quickly it loses energy when interacting with matter.

For example, given equal initial kinetic energies, an electron will penetrate further into aluminum than a heavy charged particle, and an X-ray will, on average, penetrate even further.

In biological tissue, the absorbed dose that a particular target organ receives from heavy-charged particle radiation depends not only on the energy spectrum of the particles but also on the depth and density of the tissue mass that lie between the skin surface and the target organ (for example, see Fig. 1, which demonstrates the tissue depth ionized hydrogen (proton) penetrates as a function of energy).

Fig. 1
Fig. 1

Depth dose, energy, and linear energy transfer characteristics of protons. The range of proton energies relative to the body diameter (dotted lines) and bone marrow depth (ordinate) for mice, pigs, and humans for energies up to 60 MeV. Figure reprinted by permission from Conditions for RightsLink Permissions Springer Customer Service Center GmbH:Springer-Verlag

Before the space-tourism industry takes flight and passengers start taking their electronic devices into orbit, there had better be a way for travelers to protect their digital data from the harsh environment of space. 

Between the radiation and the effects of microgravity, the typical smartphone, tablet or laptop may malfunction before you have the chance to tweet your amazing photos of Earth.

Add NASA’s worries about hackers intercepting communications and even commandeering control of satellites in space, and our electronic devices and the data they contain become even more vulnerable.

If and when your personal electronic devices succumb to these vulnerabilities in space, whether it’s during a suborbital flight on SpaceShipTwo or an extended stay at a luxury space hotel, there will likely be no resident IT expert aboard your spacecraft.

And without a working mobile device, you’ll have a hard time calling tech support back on Earth.

How, then, do astronauts aboard the International Space Station (ISS) send and safeguard their data?

In a word: carefully.

According to Backup4all, which services the laptops at the space station, data protection is essential not only to the research and science experiments astronauts perform at the orbiting lab, but also to the information they see and share on social media.

As the ISS orbits Earth 16 times a day (or about once every 90 minutes), crewmembers back up their data to 13 destinations, including external hard drives and the same cloud-storage providers that many of us use on Earth.

Those include Google Drive, Dropbox and Microsoft OneDrive. That data involves experiments concerning cancer research, “cool-flame extinction” and the use of a Robonaut in high-stress conditions, among other things.

If backup policies were not in place, NASA and its international partners at the space station would risk losing “time-sensitive, mission-critical data, like information about the crew’s health, the status of the station’s systems, results from onboard science experiments, as well as every single social media post and interview,” NASA officials said in a statement.

It would be hard for NASA’s public outreach to succeed without the breathtaking pictures of space the agency shares with its social media followers. Picture, too, the space station’s Twitter feed without its 2.3 million followers.

Now, picture yourself without access to your own data and pictures. A malfunctioning smartphone can be frustrating enough on Earth.

But how would you feel if your smartphone stopped working while you were hundreds of miles away from the planet, making it impossible for you, as a space tourist, to beam pictures and messages down to Earth?

You could avoid these future “first-world problems” by keeping data-backup tools at the ready.

Here on Earth, 140,000 hard drives crash every week in the United States alone, according to the cybersecurity news website CSO.com.

Recovering a crashed computer can cost upward of $7,500, with no guarantee of success.

Even worse, every year about 70 million smartphones fall victim to theft, whether they’re physically stolen or digitally hacked, according to a study from the Kensington Computer Products Group. The study found that the cost of losing a laptop or other mobile electronic device can greatly exceed the cost of the device itself “thanks to lost productivity, the loss of intellectual property, data breaches, and legal fees.”

The good news is that the ISS can be the ultimate symbol of data protection. It already is a symbol of the triumph of science, technology, engineering and mathematics (STEM).

Translating that symbol into a call to action should be a national priority. Creating a call to action “is a design challenge, to be sure,” said Janil Jean, director of overseas operations for LogoDesign.net.

“It is not, however, an insurmountable one.

Not when it is easier — at the moment — to find a ‘no smoking’ sign than it is to find a sign that warns against not leaving data vulnerable to loss or theft.”

I agree with that statement, just as I believe in the value of the mission of the ISS.

That value has many denominations, from the actual work that crewmembers do every day to the data that serves as a digital record of the research these men and women perform on behalf of humankind.

We should emulate their example by doing the practical thing, which is also the smart thing: treating data as a personal commodity and a public good that is too precious to squander, too powerful to sacrifice and too potent to surrender — and that is equally as vulnerable in space as it is on the ground, if not more vulnerable.

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