Create one production-ready image asset for the StoryVault mobile app.
Persona: Captain Nova (space_adventure_captain).
Asset name: companion_space_whale_calf.
Asset label for prompt context only: Space Whale.
Step: companion.
Usage: choice_icon.
Target size/aspect intent: 512x512.

Image description:
A gentle baby whale floating through stars, translucent fins, soft blue glow, kind expression.

Art direction:
- Style: premium children storybook, cinematic space adventure, soft 3D illustration, high contrast, cheerful, safe, magical
- Palette: deep navy, cosmic purple, electric blue, warm yellow, emerald green, coral red
- Lighting: soft glow, rim light, star sparkle highlights
- Character consistency: Captain Nova is a warm childlike astronaut guide with a round helmet, star headphones, blue-gold suit accents, and a friendly expression.
- Safety: No weapons, no frightening aliens, no realistic danger, no sharp horror elements.

Hard requirements:
- Do not include any readable text, letters, numbers, captions, logos, watermarks, labels, UI text, or signage inside the image.
- Create a polished rounded-square storybook choice tile. Use a clean dark navy or cosmic background inside the tile and keep the main subject centered with comfortable padding. Do not include a text label.
- Do not include Captain Nova, astronauts, children, guides, or mascot characters. Show only the requested asset subject.
- Use a premium children storybook look with soft 3D forms.
- Use kid-safe, cheerful expressions and rounded shapes.
- Avoid horror, weapons, realistic danger, aggressive expressions, or adult themes.
- Output a single image asset, not a collage and not a phone UI mockup.