Concept:
Private astronaut missions are commercial space missions where private companies collaborate with NASA to send astronauts to space stations like the ISS.
• Helps in commercial space exploration.
• Expands private participation in space missions.
• Supports research and tourism in space.
Step 1: Understand the role of private aerospace companies.
NASA partners with private companies for:
Launching astronauts and cargo to space
to reduce costs and improve innovation.
Step 2: Identify the company involved.
The company that signed this agreement is:
SpaceX
which has already carried astronauts to the ISS through Crew Dragon missions.
Step 3: Eliminate incorrect options.
• Vast Space -- private station developer
• Blue Origin -- separate space tourism missions
• Boeing -- CST-100 Starliner
• SpaceX -- correct
Step 4: Final conclusion.
Hence, the correct answer is:
\[
\boxed{\text{SpaceX}}
\]