In Phase 3 of NASA’s HAVOC proposed mission for a buoyant probe to the Venusian atmosphere, a crewed atmospheric probe de-orbits from an orbiting mothership. The probe is a solar-electric propelled airship which would travel with the upper atmospheric winds

enter image description here NASA

During the planned mission, the probe would most likely confine itself to mid-latitudes to avoid Hadley Cell updrafts and downdrafts near the equator and polar collars.

enter image description here Wikipedia

The orbiting mothership's inclination is fixed at the time of probe de-orbiting. The probe location is at the mercy of local winds (and its own very low maneuvering speed).

At the end of the one-month mission, the crew vehicle would separate from the airship and make a rocket powered ascent to rendezvous with the orbiting mothership.

enter image description here https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQcGAewWaLAqMbevcjJexmkfX_0eGhlQBJLlH1Ds_BboNJ99JMx9zUcGc2_F_Fl-u5t3EQ&usqp=CAU

My concern is for an emergency abort-to-orbit event (such as loss of buoyancy control). Successful rendezvous with the orbiter would require the probe to be on the orbiter’s ground track so the orbital inclinations could match.

What choice of mothership's orbital inclination would maximize the chance of success for an emergency abort-to-orbit?

  • $\begingroup$ From the picture on this NASA site, it appears the "gondola" were the human would be, would be detachable from the inflated "buoyancy bag". How quickly it could decouple would be interesting to know, particularly in an emergency situation. I'm assuming the gondola would have the means of propulsion to get it into an orbiting situation. $\endgroup$
    – Fred
    Jul 27, 2023 at 5:29
  • $\begingroup$ Frankly the idea of inflating an airship gasbag while on the way down gives me the heebie-jeebies. $\endgroup$ Jul 27, 2023 at 21:44
  • $\begingroup$ @DarthPseudonym ... me, too. That's what started me thinking about abort-to-orbit options during the mission. At least in a failure-to-inflate scenario, you are still on the ground track for the mothership's orbit and you have a chance of rendezvousing with it. $\endgroup$
    – Woody
    Jul 27, 2023 at 23:45
  • $\begingroup$ Appears this was a 'science project', not something that was seriously proposed. Lots of work was done on entry, not sure much was done on ascent. $\endgroup$ Jul 28, 2023 at 4:43


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