I like ensemble pieces…you had some of that here, despite the “man alone” scenario.
The most realistic scenario starts like CONTACT (no ships at first, just signals) mixed with the behind the scene goings on with the movie Arrival, with many teams devising protocols.
The one way “suicide mission” would have been in the past, with this:
en.wikipedia.org
That actually looks more like HM anyway, but it has a SNAP reactor and zip propellants both.
The astronaut would have wrangled with the object behind the TETON EVENT 1972 daylight fireball, with shuttle orbiter payload bay size based on how long the body was…not (just) HEXAGON.
The researchers would have been unaware of the DoD intercepting the probe—and the film then is more like THE CHINA SYNDROME mixed with THE KREMLIN LETTER than Capricorn One.
No doomsday scenario , no fanciful amoebae with the energy density of zero-point (Nomad of TOS did that anyway.)
Shuttle returns the Bracewell probe with a mummy of a life-form, explaining some servicemen seeing an alien. The enemy here is secrecy, with people the world over able to hear the broadcast, so the secret would have to come out.
No possession, no saucers, apart from the Bracewell probe’s aero shell the Gemini pilots cut away.
Rotation