It is normal and natural for us humans to want everything to be neatly resolved. The Ascension Day narrative of Jesus safely returned to his throne in heaven has been enduringly popular, but that is not the narrative the New Testament gives us. The New Testament only tells us of Jesus’ bewildered disciples staring into heaven, and then casting lots to select a new apostle to replace Judas - just in case it was important.
What we learn is that God has chosen to put his mission into our hands. He trusts us, even though he knows that our understanding is limited. There is little point in sitting around waiting for an ‘act of God’ because God is waiting for us to act. It is for us to work out what sort of christians we need to be.