Voyager 1 & Insect Gears| SciByte 102

Voyager 1 & Insect Gears| SciByte 102

We take a look at Voyager 1’s journey, a possible HIV vaccine, gears in nature, Curiosity news, and as always take a peek back into history and up in the sky this week.

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— Show Notes: —

Voyager 1’s Journey

  • NASA says that the Voyager 1 spacecraft is in interstellar space and actually made the transition about a year ago
  • There is however a bit of an argument on the semantics of whether Voyager 1 is still inside or outside of our Solar System
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  • \”Edge of the Solar System?\”
  • There is no one simple definition of where the \’edge of the solar system\’ is
  • The heliosphere is a region of space dominated by the Sun, a sort of bubble of charged particles in the space surrounding the Solar System.
  • Although electrically neutral atoms from the extrasolar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself.
  • Some scientists define that as the edge of the solar system, while others define it at the outer boundary of the Oort cloud
  • The Oort cloud is a hypothesized spherical cloud of predominantly icy planetesimals that may lie roughly 50,000 AU, or nearly a light-year, from the Sun
  • This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun
  • The outer Oort cloud is only loosely bound to the Solar System, and thus is easily affected by the gravitational pull both of passing stars and of the Milky Way itself
  • Shift in the Magnetic Field
  • Solar plasma produces a distinctive magnetic field because it all comes from the same source
  • Scientists expected that the field would shift in interstellar space, where particles flit around in all directions
  • Because of this, scientists thought would be the key signature of interstellar space: a shift in the direction of the magnetic field
  • Without a Shift in the Magnetic Field
  • Since there was no clear change in the magnetic fields, scientists determined they needed to look at the properties of the plasma instead
  • The Sun’s heliosphere is filled with ionized plasma from the Sun, outside that bubble, the plasma comes from the explosions of other stars millions of years ago
  • The main tell-tail difference between the two is that interstellar plasma is denser.
  • The real instrument that was designed to make the measurements on the plasma quit working in the 1980’s
  • Instead they used the plasma wave instrument, located on the 10-meter long antennas on Voyager 1 and a massive Coronal Mass Ejection from the Sun
  • All Scientists Never Agree
  • Some scientists, including a few holdouts on the Voyager team, have written a paper demonstrating how plasma could become dense enough within the heliosphere to produce the measurements seen
  • Several well-publicized studies made that claim the team lacked evidence of what they thought would be the key signature of interstellar space: a shift in the direction of the magnetic field
  • Solar plasma produces a distinctive magnetic field because it all comes from the same source
  • Scientists expected that the field would shift in interstellar space, where particles flit around in all directions
  • Getting The Data
  • Voyager 1 is 18.7 billion km [11.6 billion miles] from the sun, or about 125 astronomical units
  • Voyager mission controllers still talk to or receive data from Voyager 1 and Voyager 2 every day
  • Emitted signals are currently very dim, at about 23 watts, the power of a refrigerator light bulb and takes more than 17 hours for a radio signal to travel from the spacecraft
  • By the time the signals get to Earth, they are a fraction of a billion-billionth of a watt
  • The signal strength is so incredibly weak that it takes both a 230-foot and a 110-foot-diameter antenna to receive our highest resolution data
  • Data from Voyager 1′s instruments are transmitted to Earth typically at 160 bits per second and the signals from Voyager 1 takes about 17 hours to travel to Earth.
  • After the data are transmitted to JPL and processed by the science teams, Voyager data are made publicly available
  • What the Data Says
  • Other astrophysicists say the evidence is overwhelming that Voyager 1 has crossed the heliopause, but acknowledge that they have to determine why the magnetic field direction didn’t shift
  • The data shows that Voyager 1 in certainly in a new region at the edge of the solar system where things are changing rapidly
  • The data is also changing in ways that the team didn’t expect
  • After further review, the Voyager team generally accepts the August 2012 date as the date of interstellar arrival
  • The charged particle and plasma changes were what would have been expected during a crossing of the heliopause
  • Coronal Mass Ejection Data
  • A CME erupted from the Sun in March 2012, and eventually arrived at Voyager 1′s location 13 months later, in April 2013
  • Because of the CME, the plasma around the spacecraft began to vibrate like a violin string.
  • The pitch of the oscillations helped scientists determine the density of the plasma
  • Those particular oscillations meant the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the outer layer of the heliosphere
  • The plasma wave science team reviewed its data and found an earlier, fainter set of oscillations in October and November 2012 from other CMEs
  • Extrapolation of measured plasma densities from both events, the team determined Voyager 1 first entered interstellar space in August 2012
  • Sounds of \’Interstellar Space\’
  • YouTube | Voyager Captures Sounds of Interstellar Space | NASA Jet Propulsion Laboratory
  • The graphic shows the frequency of the waves, which indicate the density of the plasma.
  • Colors indicate the intensity of the waves, or how \”loud\” they are, with red indicating the loudest waves and blue the weakest.
  • The soundtrack reproduces the amplitude and frequency of the plasma waves as \”heard\” by Voyager 1.
  • The waves detected by the instrument antennas can be simply amplified and played through a speaker
  • This helped the Voyager science team calculate the density of interstellar plasma
  • The Future of Voyager 1
  • While Voyager 1 will keep going, we will not always be able to communicate with it, as we do now
  • NASA estimates that Voyager 1 has enough plutonium fuel to keep all its instruments powered for another seven years
  • Moving outward from the sun at about 3.5 AU per year there are estimates of how long it will be before it reaches various locations
  • In 2025 all instruments will be turned off, and the science team will be able to operate the spacecraft for about 10 years after that to just get engineering data
  • It will take 300 years to reach the Oort cloud
  • Scientists do not know when Voyager 1 will reach the undisturbed part of interstellar space where there is no influence from our Sun
  • They also are not certain when Voyager 2 is expected to cross into interstellar space, but they believe it is not very far behind.
  • In the year 40,272 AD, Voyager 1 will come within 1.7 light years of an obscure star in the constellation Ursa Minor
  • Multimedia
  • YouTube | Voyager Captures Sounds of Interstellar Space | NASA Jet Propulsion Laboratory
  • YouTube | Voyager Welcomed To Interstellar Space | VideoFromSpace
  • Further Reading / In the News
  • Messages To Voyager: Welcome to Interstellar Space |
  • [Listen to the Sounds of Interstellar Space, Recorded by Voyager 1] |
  • Voyager 1 spacecraft reaches interstellar space, study confirms |
  • It\’s Official: Voyager 1 Is Now In Interstellar Space
  • At last, Voyager 1 slips into interstellar space | Atom & Cosmos | Science News
  • Voyager 1 Probe Captures 1st-Ever Sounds of Interstellar Space (Video) |
  • Heliosphere | Wikipeida
  • Oort Cloud | Wikipeida


HIV/AIDS Vaccine

  • An HIV/AIDS vaccine candidate being developed by researchers at Oregon Health & Science University
  • The Vaccine
  • The promising vaccine is being tested through the use of a non-human primate form of HIV simian immunodeficiency virus, or SIV, which causes AIDS in monkeys
  • In fact SIV is roughly 100x more deadly that HIV
  • It involves the use of cytomegalovirus, or CMV, a common virus already carried by a large percentage of the population
  • The researchers discovered that pairing a modified CMV virus with SIV had a unique effect
  • The modified version of CMV engineered to express SIV proteins generates and indefinitely maintains so-called \”effector memory\” that are capable of searching out and destroying SIV-infected cells
  • The Testing
  • About 50 percent of monkeys given highly pathogenic SIV after being vaccinated with this vaccine became infected with SIV but over time eliminated all trace of SIV from the body
  • The vaccine mobilized a T-cell response that was able to overtake the SIV invaders in 50 percent of the cases treated
  • In fact, testing suggests SIV was banished from the host
  • The lab is now investigating the possible reasons why only a subset of the animals treated had a positive response in hopes that the effectiveness of the vaccine candidate can be further boosted
  • Further Reading / In the News
  • AIDS vaccine candidate appears to completely clear virus from the body |


Natural Insect Gears

  • Michael Thalleen ‏@ThalleenM | Check This Out!
  • Natural Insect Gears
  • Answer
  • To the best of our knowledge, the mechanical gear was invented sometime around 300 B.C.E. by Greek mechanics who lived in Alexandria
  • Issus coleoptratus, planthopper, have an intricate gearing system that locks their back legs together, allowing both appendages to rotate at the exact same instant, causing the tiny creatures jump forward.
  • The finding, is believed to be the first functional gearing system ever discovered in nature
  • Gearing
  • The reason for the gearing, they say, is coordination, to jump both of the insect’s hind legs must push forward at the exact same time
  • The skeleton is used to solve a complex problem that the brain and nervous system can’t
  • The gears are located at the top of the insects’ hind legs and include 10 to 12 tapered teeth, each about 80 micrometers wide (or 80 millionths of a meter).
  • In all the planthoppers studied, the same number of teeth were present on each hind leg, and the gears locked together neatly
  • Scientists used electron microscopes and high-speed video capture to discover the existence of the gearing and figure out its exact function.
  • They jump at speeds as high as 8.7 miles per hour, and 50,000 teeth per second
  • They cock their back legs into a jumping position, then pushed forward, with each moving within 30 microseconds (30 millionths of a second)
  • No \’Gears\’ in Adults
  • Adults of the same insect species don’t have any gearing-as the juveniles grow up and their skin molts away
  • The adult legs are synchronized by an alternate mechanism
  • Adults are bigger and heavier, Burrows say, so perhaps leg-to-leg friction syncs motions without the need for gear teeth
  • It is hypothesize that this could be explained by the fragility of the gearing, if one tooth breaks, it limits the effectiveness of the design
  • That weakness isn’t such a big problem for the juveniles, who repeatedly molt and grow new gears before adulthood
  • However for the mature Issus, replacing the teeth would be impossible
  • Multimedia
  • YouTube | Working Gears Evolved in Plant-Hopping Insect | SciAmerican
  • Image Animation of the Gears in Action |
  • Further Reading / In the News
  • Young insect legs have real meshing gears | Zoology |
  • This Insect Has The Only Mechanical Gears Ever Found in Nature |



Looking back

  • September, 23 1846 : 167 years ago : Neptune Discovered : The German astronomer Johan G. Galle discovered Neptune after only an hour of searching, within one degree of the position that had been computed by Urbain-Jean-Joseph Le Verrier. Independently of the English astronomer John C. Adams, Le Verrier had calculated the size and position of a previously unknown planet, which he assumed influenced the irregular orbit of Uranus, and he asked Galle to look for it.

Looking up this week

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