Here are some pen name suggestions based on your specifications:

Combining Initials & Genre:

• A.S. Vance: Classic, strong-sounding, evokes a sense of adventure common in Sci-Fi.
• A.S. Kepler: Suggests mystery and intrigue, fitting for a Sci-Fi thriller.
• S.A. Rex: Short, punchy, and memorable. "Rex" hints at power and dominance, suitable for a Sci-Fi hero or villain.
• A.S. Nova: "Nova" directly relates to space and celestial events, fitting the genre perfectly.
• S.A. Orion: "Orion" is a prominent constellation, adding a cosmic touch.

American/Canadian Names with Initials:

• Asa Sterling: Classic American-sounding name, the initials fit.
• Asher Stone: Modern yet strong, suitable for a protagonist.
• Adrian Sinclair: Sophisticated and mysterious, good for a Sci-Fi detective or intellectual character.
• Spencer Ames: Slightly less common, but still sounds very American.
• Samuel Archer: Traditional but strong, suitable for a Sci-Fi hero or leader.

More Creative Options:

• Axon Stellar: Combines a scientific term ("Axon") with a celestial one ("Stellar").
• Solarian Ames: "Solarian" evokes a sun-like energy, fitting for a powerful character.
• Arcturus Stone: "Arcturus" is a bright star, adding a cosmic element.
• Silas Vance: While not using both initials, it maintains a strong American feel and fits the Sci-Fi genre.

Remember to check if the name is already in use before settling on one. You can search online databases of authors and other creative professionals to ensure uniqueness.