The entry probe of the Galileo mission to Jupiter entered the planet’s ambiance in 1995 in fiery trend. Because the probe descended from Mach 50 to Mach 1 and generated sufficient warmth to trigger plasma reactions on its floor, it relayed knowledge concerning the burning of its warmth defend that differed from the consequences predicted in fluid dynamics fashions. New work examines what might need brought on such a discrepancy.
Researchers on the Universidade de Lisboa and the College of Illinois at Urbana-Champaign report their findings from new fluid radiative dynamics fashions utilizing knowledge transmitted from the of Galileo’s 30-second entry. The paper, published in Physics of Fluids, from AIP Publishing, employs new computational methods developed in the almost 25 years for the reason that mission.
“Early simulations for the probe design have been performed in the Nineteen Eighties,” mentioned Mario Lino da Silva, an creator on the paper. “There are some issues we will do in 2019, as a result of we’ve got the computational energy, new units, new theories and new knowledge.”
Galileo’s probe entered Jupiter’s gravity touring 47.4 kilometers per second, making it one of many quickest man-made objects ever. The fireball brought on by the descent warmed the carbon phenolic warmth defend to temperatures hotter than the solar’s floor.
Knowledge from the probe revealed the rim of the warmth defend burned considerably greater than even at the moment’s fashions would predict, measured by what is named the recession fee.
“The fireball is a form of soup the place quite a lot of issues occur on the similar time,” he mentioned. “One drawback with modeling is that there are a lot of sources of uncertainty and just one noticed parameter, the warmth defend recession fee.”
The group recalculated options of the hydrogen-helium combination the probe handed by, akin to viscosity, thermal conductivity and mass diffusion, and located the oft-cited Wilke/Blottner/Eucken transport mannequin did not precisely mannequin interactions between hydrogen and helium molecules.
They discovered the radiative heating properties of hydrogen molecules performed a major position in the extra heating the probe’s warmth defend skilled.
“The built-in warmth defend engineering margins truly saved the spacecraft,” Lino da Silva mentioned.
Lino da Silva hopes the work helps enhance future spacecraft design, together with upcoming initiatives to discover Neptune that may doubtless not attain their locations till after he has retired.
“In a manner, it’s like constructing cathedrals or the pyramids,” he mentioned. “You don’t get to see the work when it’s completed.”
Lino da Silva subsequent seems to validate a number of the simulated findings by reproducing related circumstances in a shock-tube facility tailor-made for reproducing high-speed flows.
Reference: “Computational fluid radiative dynamics of the Galileo Jupiter entry” by Mario Lino da Silva, Luis dos Santos Fernandes and Bruno Lopez, 15 October 2019, Physics of Fluids.
Physics of Fluids
Physics of Fluids is dedicated to the publication of unique theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and sophisticated or multiphase fluids.