A Mission to Touch the Sun
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A Mission to Touch the Sun Presented by: David Malaspina Based on a huge amount of work by the NASA, APL, FIELDS, SWEAP, WISPR, ISOIS teams Who am I? Recent Space Plasma Group Missions: Van Allen Probes Assistant Professor in: Magnetospheric MultiScale (MMS) Professional Researcher in the Space Plasma Group (SPG) at: Parker Solar Probe Space Plasma Physicist Studying: The Solar Wind Planetary Magnetospheres Planetary Ionospheres Plasma Waves MAVEN Electric Field Sensors Spacecraft Charging A Tale in Four Acts [1] History - How do we know that a solar wind exists? - Why do we care? - What have we learned about the solar wind? [2] Solar Wind Science - Key unanswered questions - The need for a Solar Probe [3] Preparing a Mission - A battle for funding - Mission design - Instrument design [4] A Mission to Touch the Sun - Launch - First orbits - First results Per Act: The future ~10-15 min talk + - ~5-10 min questions Act 0: Terminology Plasma: A gas so hot, the atoms separate into electrons and ions - Ionization Common plasmas: - The Sun - Lightning plasma - Neon signs, fluorescent lights - TIG welders / Plasma cutters Plasmas have complicated motions: Fluid motion and electromagnetic motion Magnetic Field Simplest magnetic fields are dipoles north and south pole Iron filings “trace” magnetic field of a bar magnet by aligning with the field Sun Plasmas and magnetic fields Electrons and ions follow magnetic field lines in helical paths Earth Plasmas “trace” magnetic field lines Act 1: History Where to start? 1859 : The Colorado Gold Rush In 1858: 620 g of gold found in Little Dry Creek (now Englewood, CO) By 1860: ~100,000 gold-seekers had moved to Colorado 1858: City of Denver founded 1859: Boulder City Town Company organized https://en.wikipedia.org/wiki/History_of_Denver https://bouldercolorado.gov/visitors/history ‘‘On the night of [September 1] we were high up on the Rocky Mountains sleeping in the open air. A lile aAer midnight we were awakened by the auroral light, so bright that one could easily read common print. Some of the party insisted that it was daylight and began the preparaon of breakfast. The light connued unl morning, varying in intensity in different parts of the heavens, and slowly changing posion. We can best describe it as the sky being overcast with very light cirrus clouds, waAed before a gentle breeze, and lighted up by an immense conflagraon. ’’ -- (Rocky Mountain News, September 17, 1859) The Carrington Event https://en.wikipedia.org/wiki/Solar_storm_of_1859 September 1859 Amateur astronomer Richard Carrington (using his private observatory, on his country estate) Observed a ‘white light’ flare from a group of Sun spots ~3 days later, Earth’s magnec field responds, Largest geoeffecve solar storm ever recorded Effects on Earth Carrington’s Sunspot sketch Aurora as bright as day in the Rocky Mountains Aurora in Panama / Caribbean Islands Telegraphs (long conductors, subject to induced currents) - some fail - some catch fire - some operate without ba@eries Solar Acvity Produces Geomagnec Acvity (!) What carries solar influences to the Earth? - Light is too fast (speed of light roughly known in 1676) Kew Observatory Magnetogram (British Geological Survey) - Must be much slower than light: parcle - A solar “wind” ? The Carrington Event https://en.wikipedia.org/wiki/Solar_storm_of_1859 September 1859 Amateur astronomer Richard Carrington (using his private observatory, on his country estate) Observed a ‘white light’ flare from a group of Sun spots ~3 days later, Earth’s magnec field responds, Largest geoeffecve solar storm ever recorded Effects on Earth Carrington’s Sunspot sketch Aurora as bright as day in the Rocky Mountains Aurora in Panama / Caribbean Islands Telegraphs (long conductors, subject to induced currents) - some fail - some catch fire - some operate without ba@eries Solar Acvity Produces Geomagnec Acvity (!) What carries solar influences to the Earth? - Light is too fast (speed of light roughly known in 1676) Kew Observatory Magnetogram (British Geological Survey) - Must be much slower than light: parcle - A solar “wind” ? Imagine: a Carrington-Class Event in the Modern World Other Hints at a Solar Wind George Ellery Hale (1908) Demonstrated that Sun spots are magnetic (Zeeman effect) Eugene Parker (1958) With knowledge of solar magnetism and ionized solar atmosphere: Introduces magnetic field into flow model Predicts a super-sonic solar wind flow Kivelson and Russell, Fig 5.1 (Space Physics: An Introduction) Predicts that magnetic fields produce a spiral pattern (Parker Spiral) First Observations USSR launches Luna 1 (1959) Reaches > 100,000 km altitude (intended for Moon, Khrushchev had ordered a new demonstration to coincide with political anniversary) Included: Scintillation Counter, Geiger counter, Magnetometer Measurements consistent with a solar wind - Australia received the data (real time only) - did not share (cold war) USA launches Mariner 2 (1962) Mission to Venus Includes Solar Plasma Spectrometer Marcia Neugebauer (JGR, 1966): Direct measurements of ions (< 2keV) Flow speeds of ~400 km/s Flow velocity variations (100’s km/s) Density variations Fast Forward ~60 years Heliosphere System Observatory (HSO) - circa 2017 Fast Forward ~60 years Fast Forward ~60 years DeForest et al. 2013 DeForest Video, SDO Video Learned a lot about the Sun, the solar wind STEREO A Earth (Wind) The Heliosphere The Sun’s gravity and energy output defines the Heliosphere and determines the dynamics of solar system bodies NASA/JSC Fisk+ 2005 ESA/Rosetta/NavCam ISAS/JAXA NASA Exploration of the Solar System is Very New Science! Parker (83 yrs old in 2010) Me! 1st Solar Probe FIELDS science working group meeting (2010, Berkeley) Discussion on: Act 1: History Act 2: Solar Wind Science Unanswered Questions Despite all this Fundamental questions about the solar wind remain unanswered (!) Unanswered Questions Despite all this Fundamental questions about the solar wind remain unanswered (!) Calvin and Hobbes, a comic by Bill Watterson Unanswered Questions Despite all this Fundamental questions about the solar wind remain unanswered (!) Calvin and Hobbes, a comic by Bill Watterson Unanswered Questions [1] What heats and accelerates the solar wind? Acceleration to super-sonic speeds in a few Rs Solar wind self-heats (Parker, 1958) during propagation from Sun Fast and slow wind accelerated by same (turbulent dissipation?) mechanism? different? (magnetic reconnection?) Adiabatic prediction Observation Chen et al. 2013 Need to measure solar wind near it’s source - where remnants of acceleration processes are observable - where most heat added Unanswered Questions [2] What solar structures are the source of the solar wind? Evidence that slow solar wind enters space as blobs While fast wind streams from coronal holes Magnec field bundles ‘disconnect’ and travel outward How do these ‘blobs’ smooth into the solar wind we see at Earth? Need to Measure the wind near its source - How does solar surface structure dictate blob structure? - How and where does smoothing occur? Unanswered Questions [3] How are solar energetic particles accelerated? Solar Energec Parcle (SEP) events: Ions moving nearly the speed of light (!) Associated with solar flares (somemes) Coronal Mass Ejecons (1%) Gradual vs. impulsive, why? Transport smears acceleraon signatures SEPs can be dangerous to : - Astronauts - Spacecra electronics - Spacecra solar panels Measure the wind near its source - What acceleration mechanisms act in SEP source regions? - How and where does smoothing occur? Discussion on: Act 2: Solar Wind Science Act 3: Preparing a Mission The Long Path to Flight 1958 - Parker’s paper on a supersonic solar wind 1958 - Simpson Committee recommends a Solar Probe 1958 - NASA founded 1962 - NASA’s Orbiting Solar Observatory concept 1974 - Helios 1 (West Germany) launches - to ~65 Rs 1976 - Helios 2 (West Germany) launches - to ~65 Rs 1978 - NASA Solar Probe concept study 1990 - NASA Solar Orbiter project concept study 2003 - National Research Council: Solar Probe mission “as soon as possible” 2003 - Solar Probe program cancelled by new NASA chief administrator 2005 - NASA: Solar Probe as “highest priority for new resources” 2008 - Solar Probe Mission Engineering Study Report 2008 - Reformulated as ‘Solar Probe Plus’ 2010 - Proposals accepted for Solar Probe Plus Instruments 2010 - Engineering begins 2017 - Spacecraft and Instruments completed 2018 - Renamed ‘Parker Solar Probe’, launched 2018 - First perihelion pass completed 2020 - Now The Long Path to Flight 1978-2008 Solar Probe Concept 3-4 Rs closest approach - Jupiter gravity assist - One-shot mission - Required nuclear power (RTGs) - Must survive extreme cold and heat, 4+ years to Jupiter and back 2009 ‘Solar Probe Plus’ Concept 9.5 Rs closest approach - Mulple Venus encounters - 19 orbits within 20 Rs - Solar powered spacecra Note the antennas Design - Distance to the Sun Mercury - 83 Rs Earth - 215 Rs Solar Probe close approach - 9.8 Rs Photosphere - 1 Rs Helios - 65 Rs Venus - 155 Rs Design - Orbits Prime Mission: 2018-2025 24 Orbits Perihelion steps down (36 Rs to 9.8 Rs) Venus gravity assists to lose angular velocity Design - Orbits Prime Mission: 2018-2025 24 Orbits Perihelion steps down (36 Rs to 9.8 Rs) Venus gravity assists to lose angular velocity We are here Design - Dangers Temperature: - Heat shield + antennas: ~1500° C (~2600° F) - if > 2° poinng error, spacecra melts - Survival heaters needed far from Sun (heat shield cools too much) - Antennas + Faraday cup in full sunlight (Helios was mirrored