$ASTR-US Astra Space, Inc. 6:50 am, November 22, 2021 • Portfolios: !!!!!!!!! • Tickers: ASTR HOL Filed Pursuant to Rule (424)(b)(3)PROSPECTUS SUPPLEMENT NO. 17 Registration No. 333-257930(to Prospectus dated August 12, 2021) ASTRA SPACE, INC.Primary Offering Of15,333,303 Shares of Common StockSecondary Offering of189,026,575 Shares of Common Stock5,333,333 Warrants to Purchase Common StockThis prospectus supplement amends and supplements the prospectus dated August 12, 2021 (as supplemented or amended from time to time, theProspectus), which forms a part of our Registration Statement on Form S-1 (No. 333-257930). This prospectus supplement is being filed to update andsupplement the information in the Prospectus with the information contained in our Current Report on Form 8-K, filed with the Securities and Exchange Commission on November 22, 2021 (theCurrent Report). Accordingly, we have attached the Current Report to this prospectus supplement.The Prospectus and this prospectussupplement relate to the issuance by us of up to an aggregate of (i) 9,999,970 shares of our Class A common stock that may be issued upon exercise of warrants to purchase Class A common stock at an exercise price of $11.50 per share (thepublic warrants) issued by Holicity Inc. (Holicity) in its initial public offering; and (ii) 5,333,333 shares of our Class A common stock that may be issued upon exercise of private placement warrants at an exerciseprice of $11.50 per share that were originally sold to X-icity Holdings Corporation (the Sponsor) in a private placement consummated simultaneously with Holicitys IPO (the private placement warrants and, together withthe public warrants, the warrants).The Prospectus and this prospectus supplement also relate to the offer and sale, from time to time, bythe selling securityholders named in this prospectus (the Selling Securityholders), or any of their permitted transferees, of (i) 5,333,333 private placement warrants; (ii) up to an aggregate of 5,333,333 shares of ourClass A common stock that may be issued upon exercise of the private placement warrants held by the Selling Securityholders; (iii) up to an aggregate of 20,000,000 shares of our Class A common stock that were issued to certaininvestors (collectively, the PIPE Investors) in a private placement in connection with the closing of the Business Combination (as defined herein); (iv) 7,500,000 shares of Class A common stock issued to the Sponsor prior toHolicitys initial public offering and registered for sale by the Selling Securityholders; (v) up to an aggregate of 92,277,793 shares of Class A common stock that were issued to certain affiliates of Astra (collectively, theAstra Affiliates) pursuant to the Business Combination Agreement (as defined herein); (vi) up to an aggregate 56,239,188 shares of Class A common stock issuable upon conversion (on a one-for-one basis) of shares of our Class B common stock, par value $0.0001 per share (Class B Common Stock) held by certain Selling Securityholders and (vii) up to an aggregate of7,676,261 shares of our Class A common stock issued in connection with our acquisition of Apollo Fusion, Inc. (Apollo Fusion), which closed on July 1, 2021 comprised of (x) 2,558,744 shares of our Class A common stock (theInitial Apollo Shares) issued to certain of the Selling Securityholders on July 1, 2021, in connection with our merger with Apollo Fusion, Inc. (Apollo Fusion) and (y) 5,117,517 additional shares of our Class Acommon stock (the Additional Apollo Shares) which may be issued to certain of the Selling Securityholders assuming (a) the achievement of all remaining performance milestones set forth in the Apollo Fusion Merger Agreement (asdefined herein), (b) we elect to pay all future milestone consideration in shares of our Class A common stock as required by the terms the Apollo Fusion Merger Agreement, and (c) the per share price used to calculate the number of sharesof our Class A common stock to be issued is $11.