Filed Pursuant to Rule (424)(b)(3)

Registration No. 333-267113

PROSPECTUS SUPPLEMENT NO. 18

(to Prospectus dated September 13, 2022)

ASTRA SPACE, INC.

34,000,000 SHARES OF CLASS A COMMON STOCK

This prospectus supplement amends and supplements the prospectus dated September 13, 2022 (as supplemented or amended from time to time, the “Prospectus”), which forms a part of our Registration Statement on Form S-1 (No. 333-267113). This prospectus supplement is being filed to update and supplement the information in the Prospectus with the information contained in our Current Report on Form 8-K, filed with the Securities and Exchange Commission (the “SEC”) on March 2, 2023 (the “Current Report”). Accordingly, we have attached the Current Report to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the offer and resale of up to 34,000,000 shares of Class A Common Stock, par value $0.0001 per share (the “Class A Common Stock”), of Astra Space, Inc. by B. Riley Principal Capital II, LLC (the “Selling Stockholder”). The shares included in the Prospectus and this Prospectus supplement consist of shares of Class A Common Stock that we may, in our discretion, elect to issue and sell to the Selling Stockholder pursuant to a common stock purchase agreement we entered into with the Selling Stockholder on August 2, 2022 (the “Purchase Agreement”). Such shares of Class A Common Stock include (i) up to 33,281,805 shares of our Class A Common Stock that we may, in our sole discretion, elect to sell to the Selling Stockholder from time to time after the date of this prospectus, pursuant to the Purchase Agreement and (ii) 718,195 shares of our Class A Common Stock we issued, or may issue if certain conditions are met, in each case, to the Selling Stockholder as consideration for its commitment to purchase shares of our Class A Common Stock in one or more purchases that we may, in our sole discretion, direct them to make, from time to time after the date of this prospectus, pursuant to the Purchase Agreement. See “The Committed Equity Financing” for a description of the Purchase Agreement and “Selling Stockholder” for additional information regarding the Selling Stockholder.

Our Class A common stock is listed on Nasdaq under the symbol “ASTR”. On March 1, 2023, the closing price of our Class A common stock was $0.5101 per share.

This prospectus supplement updates and supplements the information in the Prospectus and is not complete without, and may not be delivered or utilized except in combination with, the Prospectus, including any amendments or supplements thereto. This prospectus supplement should be read in conjunction with the Prospectus and if there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement.

Investing in our securities involves risks that are described in the “Risk Factors” section beginning on page 17 of the Prospectus.

Neither the SEC nor any state securities commission has approved or disapproved of the securities to be issued under the Prospectus or determined if the Prospectus or this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is March 2, 2023.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): March 1, 2023

Astra Space, Inc.

(Exact name of Registrant as Specified in Its Charter)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 8.01 Other Events.

On March 1, 2023, Astra Space, Inc. (the “Company”) filed a petition in the Delaware Court of Chancery (the “Court of Chancery”) pursuant to Section 205 of the Delaware General Corporation Law (the “DGCL”), seeking validation of an amendment to its certificate of incorporation increasing the authorized common stock of the Company (as further described below) and the shares issued pursuant thereto.

At a special meeting of the stockholders of the Company held on June 30, 2021 (the “2021 Special Meeting”), a majority of the then-outstanding shares of the Company’s Class A common stock and Class B common stock, voting as a single class, voted to approve the Company’s Second Amended and Restated Certificate of Incorporation, which, among other things, increased the authorized shares of the Company’s common stock from 220,000,000 to 465,000,000 shares of common stock (the “Charter Amendment”).

A recent decision of the Court of Chancery has created uncertainty regarding the validity of the Charter Amendment and whether a separate vote of the majority of the then-outstanding shares of Class A common stock would have been required under Section 242(b)(2) of the DGCL.

The Company continues to believe that a separate vote of Class A common stock was not required to approve the Charter Amendment. However, in light of the recent Court of Chancery decision, the Company filed a petition in the Court of Chancery pursuant to Section 205 of the DGCL seeking to validate the Charter Amendment and the shares issued pursuant thereto to resolve any uncertainty with respect to those matters. Section 205 of the DGCL permits the Court of Chancery, in its discretion, to validate potentially defective corporate acts and stock after considering a variety of factors.

While the Company believes that a separate vote of the Company’s Class A common stock was not required to approve the Charter Amendment at the 2021 Special Meeting, and therefore that all of the currently outstanding shares of common stock of the Company are validly issued, if the Company is not successful in the Section 205 proceeding, the uncertainty with respect to the Company’s capitalization resulting from the Court of Chancery’s decision referenced above could have an adverse effect on the Company, including on its ability to complete financing transactions, until the underlying issues are definitively resolved.

Forward-Looking Statements

This current report on Form 8-K (this “Current Report”) includes “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. All statements, other than statements of present or historical fact included in this Current Report, are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may,” “should,” “could,” “would,” “expect,” “plan,” “anticipate,” “intend,” “believe,” “estimate,” “continue,” “project” or the negative of such terms and other similar expressions that predict or indicate future events or trends or that are not statements of present or historical matters. These statements are based on various assumptions, whether or not identified herein, and on the current expectations of the Company and are not predictions of actual outcomes. Actual events and circumstances are impossible to predict and are beyond the control of the Company.

With respect to the matters addressed in this Current Report, no assurances can be made regarding the outcome of the Company’s proceeding pursuant to Section 205 of the DGCL. The Section 205 proceeding is subject to inherent uncertainties and is beyond the Company’s control and may not result in timely resolution of the uncertainty regarding the Company’s capitalization, if at all. If the Company is unsuccessful in the Section 205 proceeding, it could have a material adverse effect on the Company.

The Company cautions you that these forward-looking statements are subject to numerous risk and uncertainties, most of which are difficult to predict and many of which are beyond the control of the Company. Additional risks and uncertainties that could affect the Company and its financial results are included under the captions “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in the Company’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (the “SEC”) on

November 9, 2022, which is available on the Company’s website at https://investor.astra.com/financial-and-filings/sec-filings and on the SEC’s website at www.sec.gov. Additional information will also be set forth in other filings that the Company makes with the SEC from time to time. All forward-looking statements in this Current Report are based on information available to the Company as of the date hereof, and the Company assumes no obligation to update the forward-looking statements provided to reflect events that occur or circumstances that exist after the date on which they were made, except as required by applicable law.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.