S02 - Ep. 10 - Nov 8, 2019
Voyager 2
One year in interstellar space!
- Announced December 2018 that Voyager 2 had reached interstellar space November 5, 2018
- Region created by the solar winds produced by the sun
- Stream of particles and a magnetic field
- Keeps out particles of other stars/debris not created by our own solar system
- The end of the heliosphere
- Determine this by temperature and number of particles
- Outside is colder but much more dense
- One year on - what have we learned?
The Voyager Program
- Emerged from the Grand Tour program (developed throughout the 60s)
- Every 175 years, the outer planets align in such a way that launched objects could use gravitational assists to study the furthest bodies
- Originally meant to send several pairs of probes
- Cancelled in 1971 due to internal competition and other factors
- Replaced with proposal to only visit two planets, Jupiter and Saturn (and Saturn’s moon Titan), with Mariner-derived probes
- Mariner Project
- 1962-1973
- Launched a total of 10 probes that explored Mercury, Mars, and Venus
- Name of the replacement project
- Approved 1972
- 1977 name changed to Voyager
Voyagers
- Launched September 5, 1977
- Optimized to study Titan
- Titan’s importance - had an atmosphere
- Mission was a success
- September 12, 2013 - officially announced it reached interstellar space
- Has trajectory correction jets NASA uses to keep probe’s antenna pointed to Earth
- Expected to last only two to three more years as of 2017
- Designed to do Grand Tour
- Launched August 20, 1977
- Design
- Constructed by the Jet Propulsion Laboratory (JPL)
- Has large, parabolic, high-gain antenna to communicate with earth
- 10 scientific instruments - including a cosmic ray telescope and plasma spectrometer
- Powered by three plutonium dioxide radioisotope thermoelectric generators (RTGs)
- Sixteen hydrazine MR-103 thrusters with enough fuel to last until 2034
- April 24, 1979 - begins sending pictures back of Jupiter
- Had a 10-hour “volcano watch” - scientists interested in Europa and Io
- Passed through the plane of its rings and was bombarded with thousands of dust grains
- Jets fired many times to keep it on course
- Official end of primary mission
- November 4, 1985 -
- Discovered 10 new moons and two new rings
- August 25, 1989 - Neptune
- Four flybys
- Discovers six new moons and three major features in the planet’s clouds: the Lesser Dark Spot, the Great Dark Spot, and Scooter
- Officially renamed the project the Voyager Interstellar Mission (VIM)
- Put in low power mode to conserve energy
- December 2018 - reaches interstellar space
- Five papers have been published based on the data received
- Each one details one of the five instruments still active: a magnetic field sensor, two instruments to detect energetic particles in different energy ranges and two instruments for studying plasma
- Voyager 1 and Voyager 2 confirm that plasma outside the heliosphere is much denser than inside
- Slight compression
- As Voyager 2 cross the heliosphere threshold, it noted an increase in temperature and slight increase in plasma density
- Heliosphere is kind of like a protective bubble
- Are leaks
- Magnetic region outside the heliosphere is parallel to the magnetic region inside
- The outside region strongly influences the entry of cosmic rays into the heliosphere
- Scientists originally expected a difference outside
- Voyager 1 reported the parallel first. Voyager 2’s data confirmed it.
Future?
- Steps taken to squeeze out as much data as possible
- Heaters turned off
- Slowly turning off scientific instruments
- Scientists estimate data for only another 5 to 10 years
- Question becomes: how far away can we get?
- Have questions that might be answered
- Do the outer magnetic fields return to normal?
- What’s the heliosphere’s shape? Can one be sent down the tail?
- 300 years to Oort Cloud, 30,000 years to cross it
- Once out, it will enter into a long orbit around the heart of our galaxy
References