pekka janhunen finnish meteorological institute kumpula space centre esa estec may 19 2008 l.
Skip this Video
Loading SlideShow in 5 Seconds..
Electric Sail Technology Status Review PowerPoint Presentation
Download Presentation
Electric Sail Technology Status Review

Loading in 2 Seconds...

play fullscreen
1 / 19

Electric Sail Technology Status Review - PowerPoint PPT Presentation

  • Uploaded on

Pekka Janhunen Finnish Meteorological Institute, (Kumpula Space Centre ) ESA/ESTEC May 19, 2008 Electric Sail Technology Status Review Contents Tether manufacture Edward Haeggström et al., Univ. Helsinki, Electronics Res. Lab Tether reels Lutz Richter, DLR-Bremen Electron gun

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

Electric Sail Technology Status Review

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
pekka janhunen finnish meteorological institute kumpula space centre esa estec may 19 2008
Pekka Janhunen

Finnish Meteorological Institute,

(Kumpula Space Centre)


May 19, 2008

Electric SailTechnology Status Review
P.Janhunen, www.electric-sailing.comContents
  • Tether manufacture
    • Edward Haeggström et al., Univ. Helsinki, Electronics Res. Lab
  • Tether reels
    • Lutz Richter, DLR-Bremen
  • Electron gun
    • Mikhail Zavyalov et al., IKI-Moscow
  • Tether Direction Sensors
    • Greger Thornell et al., ÅSTC-Uppsala
  • Dynamic Tether Simulations
    • Numerola Oy company & PJ
  • Orbital Calculations
    • Giovanni Mengali et al., Univ. Pisa
  • Integration of components
tether material tech selection
P.Janhunen, www.electric-sailing.comTether material & tech selection
  • Initial material & technology study was made by Prof. S.-P. Hannula et al. at Helsinki Univ. Tech.
  • Technology options covered:
    • Laser-cut tether from metal sheet (efficiency? quality?)
    • Metal-clad fibres (CTE? radiation?)
    • Wire-wire bonding
      • Laser welding
      • Ultrasonic welding
      • Soldering (temperature range? CTE?)
      • Glueing (reliability? CTE?)
      • Wrap wire (not done at 20 um scale?)
  • Ultrasonic welding selected, others are fallbacks
wire metal selection
P.Janhunen, www.electric-sailing.comWire metal selection
  • Requirements: Good yield strength, preferably at least steel-class conductivity
  • No brittle-ductile transition at cold temperature
  • Generally: Alloying can improve yield strength, but usually destroys conductivity
  • Good-conductivity alloys:
    • 90% Cu, 10% Ag: Tensile strength 1000-1600 MPa, Density 9 g/cm3
    • 99% Al, 1% Si: Tensile strength ~300 MPa, Density 2.7 g/cm3
  • Dense metal has better micrometeoroid tolerance?
tether manufacture
P.Janhunen, www.electric-sailing.comTether manufacture
  • Prof. Edward Haeggström, Univ. Helsinki, Electronics Research Lab
    • Presented by Henri Seppänen
tether reels
P.Janhunen, www.electric-sailing.comTether reels
  • Preparatory work by Lutz Richter, DLR-Bremen
  • Baseline plan
    • Spinning reel, maybe with capstains
    • Outreeling only, or reeling both in and out
    • Ordinary or magnetic bearing
  • Other ideas also considered
  • Plan for proceeding
    • TRL 4 level work can commence when at least few metre piece of tether is available (either final-type or mockup, this is TBD)
electron gun
P.Janhunen, www.electric-sailing.comElectron gun
  • Prof. Mikhail Zavyalov, Pavel Tujrujkanov, E.N. Evlanov, Space Research Institute IKI, Moscow
  • Three new designs produced, based on IKI heritage hardware:
    • 300 V low-voltage gun for ionospheric testing
    • 20 kV/2kW baseline model for solar wind
    • 40 kV/2kW enhanced voltage model for solar wind
electron gun summary
P.Janhunen, www.electric-sailing.comElectron gun summary
  • 40 kV, 2 kW, 50 mA gun: Mass 3.9 kg including power supply (2 kg) and radiator (0.9 kg)
  • LaB6 cathode lifetime: theoretically should be at least 10 years in high vacuum
  • Overall, electron gun situation looks good: gun which actually exceeds our power requirement (~400 W) several times has <4 kg mass. Could have more than one gun for redundancy.
tether direction sensors
P.Janhunen, www.electric-sailing.comTether Direction Sensors
  • Greger Thornell, Henrik Kratz, Ångström Space Technology Center, Uppsala
  • Status: Preliminary TRL 3 -level analysis done in collaboration with ÅSTC and PJ
  • Initially, also Univ. Liege (P. Rochus et al.) looked at the topic
  • Main idea: Detect tethers optically with stereo camera, Reconstruct 3-D directions from images onboard
  • Purpose: Tether lengths must be actively fine-tuned to avoid their collisions. One must first detect them.
tether direction sensors12
P.Janhunen, www.electric-sailing.comTether Direction Sensors
  • TRL 3 analysis done, basically
  • Modest-sized cameras enough unless >10-15 AU distance
  • May have to mat-finish wires to create diffuse reflectance
  • Seeing root of tether enough to determine its direction
  • Seeing the tip would be good as tether breakage alarm
mechanical simulations
P.Janhunen, www.electric-sailing.comMechanical simulations
  • Numerola Ltd company, Jyväskylä, Finland, together with P. Janhunen
orbital calculations
P.Janhunen, www.electric-sailing.comOrbital calculations
  • University of Pisa, prof. Giovanni Mengali, Alessandro Quarta
integration of components
P.Janhunen, www.electric-sailing.comIntegration of components
  • General approach
    • Design whole s/c around electric sail
    • Add electric sail to existing s/c design
  • Spinup strategy
    • Spinup rockets
    • Siamese Twins
  • Placement of reels
    • At outer edge of s/c disk
    • At deployable booms at ends of solar panel arrays
  • High voltage path design (grounding plan)
    • Whole s/c at high positive potential
    • Only reels and electron gun at high positive potential
P.Janhunen, www.electric-sailing.comControl
  • Tethers have two degrees of freedom: in spinplane and perpendicular to spinplane
  • Thus we need two controls: potential (controls solar wind force) and length (controls angular speed)
  • Length fine-tuning strategies:
    • Reel in and out (needs reliable reeling of partly damaged tether or thicker monofilament base tether)
    • Reel out only (must have enough spare tether)
flight algorithm
P.Janhunen, www.electric-sailing.comFlight algorithm
  • Inputs (partly redundant):
    • Pointing direction of each tether (direction sensor)
    • Spacecraft potential (electron detector)
    • DC current flowing in each tether
    • Thrust (accelerometer)
  • Output commands:
    • Overall thrust (electron gun current and voltage)
    • Individual tether potentials (potentiometers)
    • Tether length fine-tuning (reel motors)
  • Running in parallel:
    • S/C body spin state control so that it conforms with tethers (star sensor and ACS)
technical status summary
P.Janhunen, www.electric-sailing.comTechnical Status Summary
  • Tether manufacture: Progressing well, required before test mission can fly
  • Tether reels: No serious problems seen, but must be done to demonstrate reeling of final-type tether
  • Electron gun: Straightforward (could use spare cathodes/guns for redundancy)
  • Tether direction sensors: Should be straightforward
  • Dynamic tether simulations: No problems seen, but should be done more comprehensively still
  • Orbital calculations: OK
  • Overall design: OK
demonstration goals
P.Janhunen, www.electric-sailing.comDemonstration goals
  • Reel to reel tether production (10 m, 100 m, 1 km, 10 km) with quality control
  • Reliable reeling of the tether
  • After these, one can make decision to build test mission. Technological development risk remaining after this is small.