Io Volcano Observer
|Operator||Under evaluation by NASA|
|Mission type||Orbiter, fly-by|
|Launch vehicle||Atlas V (401)|
|Mission duration||18-month nominal mission at Jupiter|
|Orbits||At least 6|
Io Volcano Observer (IVO) is a proposed unmanned spacecraft that, if approved and launched, would orbit Jupiter and perform at least seven flybys of Jupiter's moon Io. IVO has been proposed to NASA by the University of Arizona as both a science and engineering mission, originally as part of NASA's Discovery & Scout Mission Capability Expansion (DSMCE) concept-study program.
IVO is a low-cost, outer-planet mission that would explore Io's active volcanism and impact on the Jupiter system as a whole by measuring its global heat flow, its induced magnetic field, the temperature of its lava, and the composition of its atmosphere, volcanic plumes, and lavas.
IVO's launch would be with an Atlas V (401) rocket. Following launch, the spacecraft would perform a VEEGA trajectory, using a gravity assist at Venus and two at Earth to send the spacecraft on a Jupiter-bound trajectory. Following an Io flyby on its way in, the Io Volcano Observer would execute a Jupiter orbital insertion burn to go into an inclined orbit around Jupiter. Following an initial six-month orbit, IVO would encounter at 6-10 times during an 18-month primary mission. As IVO would be an inclined orbit (~49°), during each of these encounters would approach Io from over its south polar region, make its closest approach near the equator of Io at distances ranging from 100 to 1000 kilometers, and depart Io over its north polar region. To aid in change detection, the spacecraft would also encounter Io near the same point in Io's orbit, keeping similar lighting conditions over the course of the nominal mission. Following the primary mission, if the spacecraft and power source remains healthy, an extended mission could be approved. This extended mission could include pumping up the orbital period of IVO to one year in length as part of a test of the ASRGs life span, to monitor Io for changes over a longer time span, and to possibly encounter one of Jupiter's outer irregular satellites. Such an extended mission could last up to eight years, with the potential for up to eight additional encounters.
Io Volcano Observer (IVO) is a concept study for NASA's Discovery & Scout Mission Capability Expansion (DSMCE) that could be performed under a Discovery Program cost cap of $425 million. IVO was previously proposed for Discovery 2010; from the 40 proposals submitted to NASA's DSMCE Program, nine were selected for further study, but IVO was not selected for launch.
In February 2014, NASA released a Discovery Program 'Draft Announcement of Opportunity' for Discovery Mission #13, with a required launch readiness date of December 31, 2021. IVO will likely be one such proposal. As such, IVO has not been funded and it is still in its conceptual phase.
Active volcanism was discovered on Jupiter's moon Io by Voyager 1 in March 1979. This significant amount of volcanism on Io is the result of tidal heating, a process that has also resulted in increased internal heat within other outer planet satellites, such as Enceladus and Europa. On both of these latter moons, the tidal heating has allowed liquid water near the surface of these moons, dramatically affecting their geology and providing a possible habitat for life. Since its discovery in 1979, the volcanic activity on Io was observed by ground-based astronomers as well as the Galileo, Cassini, and New Horizons. Galileo flew by Io seven times over the course of its nearly-eight-year mission at Jupiter. However, Galileo's low downlink bandwidth resulting from its broken high-gain antenna, camera and spectrometer problems, and safing events that occurred during several of the encounters limited the amount and quality of data that could be returned from these flybys. Both Cassini and New Horizons flew by the Jupiter system at distances greater than the orbit of Callisto, the outermost of the Galilean satellites, limiting the resolution and time span of their data.
The science objectives of this proposed mission are:
- Understand Io's currently active volcanism and implications for volcanic processes on other planetary bodies throughout geologic time.
- Understand Io's interior structure and tidal heating mechanisms and implications for the coupled orbital-thermal evolution of satellites and extrasolar planets.
- Understand the processes that form mountains and paterae on Io and the implications for tectonics under high-heat-flow conditions that may have existed early in the history of other planetary bodies.
- Understand how Io affects the Jovian system, and implications for the study of otherplanetary systems.
- Seek evidence for activity in Io's deep interior and understand the generation of internal magnetic fields.
The payload includes narrow angle and wide angle cameras, dual fluxgate magnetometers, a thermal mapper, dual ion and neutral mass spectrometers, and dual plasma ion analyzers. The Principal investigator is Alfred McEwen.
- Radiation-hard Narrow-Angle Camera (RCam) 10 μrad/pixel CMOS detector with 2 e-read noise, color imaging in 15 bandpasses from 200-1100 nm, framing images (clear-filter) for movies and optical navigation.
- Thermal Mapper (ThM): 125 μrad/pixel, ten bandpasses for thermal mapping and silicate compositions. The instrument was derived from the Mars Odyssey THEMIS but with an improved microbolometer detector.
- Ion and Neutral Mass Spectrometer (INMS): Mass range 1-1000 amu/q. Contributed by the University of Bern and the Swedish Institute of Space Physics.
- Fluxgate Magnetometers (FGM): two units with a sensitivity of 0.01 nT. Contributed by IGEP, Braunschweig.
- Payload Enhancement Options: (1) Second INMS for better coverage; (2) Wide-angle camera for more stereo mapping; (3) Contributed near-IR imaging spectrometer; (4) Student built dust detector.
- McEwen, Alfred (August 24, 2009). "Io Volcano Observer (IVO)" (pdf). National Research Council. Retrieved 2010-02-08.
- Green, James (March 12, 2008). "Planetary Science Update and Lunar Science Plans" (pdf). Goddard Space Flight Center. NASA. Retrieved 2010-02-08.
- James L., Green (June 23, 2008). "Planetary Science Division Update" (PDF). NASA. Retrieved 10 November 2009.
- McEwen, Alfred (December 12, 2008). "Io Volcano Observer (IVO)" (pdf). Berkley Io Workshop. Retrieved 2010-02-08.
- "NASA Discovery Program Draft Announcement of Opportunity". NASA Science Mission Directorate (SpaceRef). 2014-02-19.
- Morabito, L. A.; et al. (1979). "Discovery of currently active extraterrestrial volcanism". Science 204 (4396): 972. Bibcode:1979Sci...204..972M. doi:10.1126/science.204.4396.972. PMID 17800432.
- Perry, J.; et al. (2007). "A Summary of the Galileo mission and its observations of Io". In Lopes, R. M. C.; and Spencer, J. R. Io after Galileo. Springer-Praxis. pp. 35–59. ISBN 3-540-34681-3.
- McEwen, A.; et al. (2010). "Science Rationale for an Io Volcano Observer (IVO) Mission" (PDF). "LPSC XLI". Abstract #1433.
- McEwen, Alfred; Elizabeth Turtle, Kenneth Hibbard, Edward Reynolds and Elena Adams. (January 2014). "Io Volcano Observer (IVO): Budget travel to the outer Solar System". Acta Astronautica 93: 539–544. doi:10.1016/j.actaastro.2012.05.028. Retrieved 2014-03-13.