Asptro is a contract bridge

Contract bridge

Contract bridge, usually known simply as bridge, is a trick-taking card game using a standard deck of 52 playing cards played by four players in two competing partnerships with partners sitting opposite each other around a small table...

  bidding convention used to intervene over a 1NT opening bid. It is a hybrid of the Astro

Astro (convention)

Astro is a contract bridge bidding convention used to intervene over an opponent's 1NT opening. Requiring an unbalanced hand with at least nine cards in two suits, at least one of which is a major, Astro is initiated by a 2-level overcall in a minor suit:...

 and Aspro conventions, thus the name.

• 2 shows at least 5-4 either way round in hearts, the anchor, and a minor suit
  Minor suit
  In contract bridge the minor suits are diamonds and clubs . They are given that name because contracts made in those suits score less than contracts made in the major suits , and they rank lower in bidding. In particular, one can make game with a bid of 4 in a major suit, while a bid of 5 is...
  
  . Exceptionally the intervenor holds hearts and spades with preference for spades.
• 2 shows at least 5-4 either way round in spades, the anchor, and another suit. If the other suit is hearts, there is preference for hearts.
• 2 and 2 are natural.

Partner can bid two of the anchor suit, 2M, expecting to play that contract (sign off). 2 is a non-forcing enquiry, if available, and 2NT is a forcing enquiry. Other replies are natural.

After a 2 reply, the 2 intervenor passes with five diamonds or bids the 5 card suit, always the unknown one with 5-5.

After a 2NT reply, the intervenor routinely bids the unknown suit. Both the anchor and the unknown major imply both majors with preference for the new one. Thus 3 and 3 may be refined, such as by a strength difference with 3 stronger.