Cover - shares	3 Months Ended
	Mar. 31, 2025	May 10, 2025
Document Information Line Items
Entity Registrant Name	HORIZON SPACE ACQUISITION I CORP.
Entity Central Index Key	0001946021
Document Type	10-Q
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Small Business	true
Entity Shell Company	true
Entity Emerging Growth Company	true
Entity Current Reporting Status	Yes
Document Period End Date	Mar. 31, 2025
Entity Filer Category	Non-accelerated Filer
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2025
Entity Ex Transition Period	false
Entity Common Stock Shares Outstanding		4,168,739
Entity File Number	001-41578
Entity Incorporation State Country Code	E9
Entity Address Address Line 1	1412 Broadway
Entity Address Address Line 2	21st Floor
Entity Address Address Line 3	Suite 21V
Entity Address City Or Town	New York
Entity Address State Or Province	NY
Entity Address Postal Zip Code	10018
City Area Code	646
Local Phone Number	257-5537
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Units Consisting Of One Ordinary Shares Member
Document Information Line Items
Security 12b Title	Ordinary Share, $0.0001 par value
Trading Symbol	HSPOU
Security Exchange Name	NASDAQ
Ordinary Shares Capital Member
Document Information Line Items
Security 12b Title	Ordinary Shares, par value $0.0001 per share
Trading Symbol	HSPO
Security Exchange Name	NASDAQ
Redeemable Warrant Member
Document Information Line Items
Security 12b Title	Ordinary Share at an exercise price of $11.50 per share
Trading Symbol	HSPOW
Security Exchange Name	NASDAQ
Rights Each Whole Right To Acquires Member
Document Information Line Items
Security 12b Title	one Ordinary Share
Trading Symbol	HSPOR
Security Exchange Name	NASDAQ