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SpaceX is launching NASA's $80 million Deep Space Atomic Clock tonight
NASA JPL takes a first step toward a GPS for space.
- Spacecraft have no independent navigation systems onboard. They rely on navigation instructions sent from Earth, which can take about 40 minutes to reach them.
- The presence of an onboard atomic clock would radically streamline spacecraft navigation and is crucial to autonomous space exploration missions.
- A SpaceX Falcon Heavy rocket will take NASA's Deep Space Atomic Clock up for a year-long mission starting June 24, 2019.
On June 24, 2019, a SpaceX Falcon Heavy will carry into space the Orbital Test Bed Satellite from General Atomics Electromagnetic Systems. Aboard that platform will be NASA JPL's Deep Space Atomic Clock. This toaster-oven sized device has been under development for 20 years at a mission cost of $80 million, and if its year-long test flight goes well, it has the potential to revolutionize the manner in which spacecraft navigate.
Image source: Nasa JPL/General Atomics Electromagnetic Systems
Why this is a big deal
The current system for directing spacecraft to their destinations is really slow, with a built-in time lag that makes quick navigational changes basically impossible. The system works like this:
- To establish a craft's current position — the first essential step in directing it forward — ground control sends a signal from a large Earth-based antenna to the ship.
- The ship receives that signal and bounces it back to a large antenna on Earth.
- Ground control calculates the current position and speed of the craft by using an Earth-based atomic clock to precisely measure the amount of time that's elapsed since the first signal was transmitted.
- Once ground control — sort of — knows where the craft is now, it can finally issue navigation instructions to it.
Okay, so here's the issue. In number 4 above, ground control's calculation doesn't really tell control where the craft is currently — it tells control where it was when the positioning signal began its return trip. As spacecraft get further and further away, this inaccuracy becomes more and more of an issue. If humans were traveling to Mars, for example, steps 1 through 4 would take an average of 40 minutes. Yes, ground calculations can estimate the ship's current location based on its previous location and speed, but that's not the same as knowing. And Mars is close by — as craft move further and further into the cosmos, the lag lengthens and lengthens, and if unanticipated conditions in space require a prompt course-correction from home, well, it's just not possible.
Image source: Vadim Sadovski/Shutterstock/Big Think
A “GPS” in space
As we travel around down here in our cars, we use GPS to navigate. Each GPS satellite has its own atomic clock that allows it to triangulate our vehicle's location by tracking the time it takes for a ping coming from our car to reach a trio of three GPS satellites. Given the relatively short distance — compared to space travel — between our roads and our satellites, this all happens pretty quickly.
The hope for the compact Deep Space Atomic Clock is that it can do the same for spacecraft. If a spacecraft has its own reliable and accurate time reference, steps 1 through 4 above can be reduced to simply one: step 4. When navigation instructions are sent from Earth, a craft can measure the time it took them to arrive, work out its own position and speed, and immediately implement the new guidance.
Another possibility is that atomic clocks could be placed into orbit around a planet and act as a GPS-style system that would help human and robots on the surface navigate the planet.
The greatest challenge in building a space atomic clock is that it has to be extremely accurate. Given the great distances that spacecraft must travel, even tiny errors in time-tracking can have catastrophic results considering the number of miles over which such inaccuracies would then multiply. They could mean crash-landing in unintended locations, or missing a planet — or even an entire region of space — altogether.
In testing here on Earth, the Deep Space Atomic clock meets this challenge — it's off by just a single second every 10 million years.
The accuracy of the Deep Space Atomic Clock
Standard atomic clocks, and even wristwatches, measure vibrations in a quartz crystal to keep track of time. A continuous electric signal fed into the crystal keeps it vibrating, back and forth, like minute — in the tiny sense — ticks of a clock.
In the case of a consumer timepiece, the displayed time ends up drifting out of accuracy. In a terrestrial atomic clock, the measurements remain spot-on through the measurement of certain atoms according to the frequencies of light they emit. Unfortunately, these atomic clocks can be thrown off by exposure to external magnetic fields and changes in temperature.
The Deep Space Atomic Clock, on the other hand, keeps track of a number amount of mercury ions — JPL says it's fewer of these ions than you'd find in a can of tuna — that are held in electromagnetic traps. In essence, these traps give the ions a protective shell that helps shield them from outside influences.
The point of the mission is to see if, over the course of a year, the Deep Space Atomic Clock can remain stable in orbit, or if its timekeeping is disrupted by being in space. If its timekeeping remains solid, we may see it being deployed on missions as soon as the 2030s.
The Deep Space Atomic Clock
Image source: NASA JPL
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This storm rained electrons, shifted energy from the sun's rays to the magnetosphere, and went unnoticed for a long time.
- An international team of scientists has confirmed the existence of a "space hurricane" seven years ago.
- The storm formed in the magnetosphere above the North magnetic pole.
- The storm posed to risk to life on Earth, though it might have interfered with some electronics.
What do you call that kind of storm when it forms over the Arctic ocean?<iframe width="730" height="430" src="https://www.youtube.com/embed/8GqnzBJkWcw" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p> Many objects in space, like Earth, the Sun, most of the planets, and even some large moons, have magnetic fields. The area around these objects which is affected by these fields is known as the magnetosphere.</p><p>For us Earthlings, the magnetosphere is what protects us from the most intense cosmic radiation and keeps the solar wind from affecting our atmosphere. When charged particles interact with it, we see the aurora. Its fluctuations lead to changes in what is known as "space weather," which can impact electronics. </p><p>This "space hurricane," as the scientists are calling it, was formed by the interactions between Earth's magnetosphere and the <a href="https://en.wikipedia.org/wiki/Interplanetary_magnetic_field" target="_blank" rel="noopener noreferrer">interplanetary magnetic field,</a> the part of the sun's magnetosphere that goes out into the solar system. It took on the familiar shape of a cyclone as it followed magnetic fields. For example, the study's authors note that the numerous arms traced out the "footprints of the reconnected magnetic field lines." It rotated counter-clockwise with a speed of nearly 7,000 feet per second. The eye, of course, was still and <a href="https://www.sciencealert.com/for-the-first-time-a-plasma-hurricane-has-been-detected-in-space" target="_blank" rel="noopener noreferrer">calm</a>.</p><p>The storm, which was invisible to the naked eye, rained electrons and shifted energy from space into the ionosphere. It seems as though such a thing can only form under calm situations when large amounts of energy are moving between the solar wind and the upper <a href="https://www.reading.ac.uk/news-and-events/releases/PR854520.aspx" target="_blank">atmosphere</a>. These conditions were modeled by the scientists using 3-D <a href="https://www.nature.com/articles/s41467-021-21459-y#Sec10" target="_blank">imaging</a>.<br><br>Co-author Larry Lyons of UCLA explained the process of putting the data together to form the models to <a href="https://www.nbcnews.com/science/space/space-hurricane-rained-electrons-observed-first-time-rcna328" target="_blank">NBC</a>:<br><br>"We had various instruments measuring various things at different times, so it wasn't like we took a big picture and could see it. The really fun thing about this type of work is that we had to piece together bits of information and put together the whole picture."<br><br>He further mentioned that these findings were completely unexpected and that nobody that even theorized a thing like this could exist. <br></p><p>While this storm wasn't a threat to any life on Earth, a storm like this could have noticeable effects on space weather. This study suggests that this could have several effects, including "increased satellite drag, disturbances in High Frequency (HF) radio communications, and increased errors in over-the-horizon radar location, satellite navigation, and communication systems."</p><p>The authors <a href="https://www.nature.com/articles/s41467-021-21459-y#Sec8" target="_blank" rel="noopener noreferrer">speculate</a> that these "space hurricanes" could also exist in the magnetospheres of other planets.</p><p>Lead author Professor Qing-He Zhang of Shandong University discussed how these findings will influence our understanding of the magnetosphere and its changes with <a href="https://www.eurekalert.org/pub_releases/2021-03/uor-sho030221.php" target="_blank" rel="noopener noreferrer">EurekaAlert</a>:</p><p>"This study suggests that there are still existing local intense geomagnetic disturbance and energy depositions which is comparable to that during super storms. This will update our understanding of the solar wind-magnetosphere-ionosphere coupling process under extremely quiet geomagnetic conditions."</p>
Research reveals a new evolutionary feature that separates humans from other primates.
- Researchers find a new feature of human evolution.
- Humans have evolved to use less water per day than other primates.
- The nose is one of the factors that allows humans to be water efficient.
A model of water turnover for humans and chimpanzees who have similar fat free mass and body water pools.
Credit: Current Biology
Being skeptical isn't just about being contrarian. It's about asking the right questions of ourselves and others to gain understanding.
- It's not always easy to tell the difference between objective truth and what we believe to be true. Separating facts from opinions, according to skeptic Michael Shermer, theoretical physicist Lawrence Krauss, and others, requires research, self-reflection, and time.
- Recognizing your own biases and those of others, avoiding echo chambers, actively seeking out opposing voices, and asking smart, testable questions are a few of the ways that skepticism can be a useful tool for learning and growth.
- As Derren Brown points out, being "skeptical of skepticism" can also lead to interesting revelations and teach us new things about ourselves and our psychology.