Exhibit 2.1

AMENDMENT NO. 2 TO BUSINESS COMBINATION AGREEMENT

This AMENDMENT NO. 2 TO BUSINESS COMBINATION AGREEMENT (this “Amendment”), is made and entered into as of April 2, 2024, by and among Mars Acquisition Corp., a Cayman Island exempted company (the “Purchaser”), ScanTech AI Systems Inc., a Delaware corporation and a wholly owned subsidiary of Mars (“Pubco”), Mars Merger Sub I Corp., a Cayman Islands exempted company and a wholly owned subsidiary of Mars (“Purchaser Merger Sub”), Mars Merger Sub II LLC, a Delaware limited liability company and a wholly owned subsidiary of Pubco (“Company Merger Sub”), ScanTech Identification Beam Systems, LLC, a Delaware limited liability company (the “Company” or “ScanTech”), and Dolan Falconer in the capacity as the representative from and after the Effective Time for the Company Holder Participants as of immediately prior to the Effective (the “Seller Representative”). Capitalized terms not otherwise defined in this Amendment shall have the meaning given to them in the Business Combination Agreement (as defined below).

W I T N E S S E T H:

WHEREAS, the parties hereto are parties to a Business Combination Agreement, dated as of September 5, 2023 (the “Business Combination Agreement”) by and among, (i) the Purchaser, (ii) Pubco, (iii) Purchaser Merger Sub, (iv) the Company Merger Sub, (v) ScanTech and (vi) the Seller Representative (collectively, the “Parties”);

WHEREAS, the Purchaser i) issued an aggregate of 2,470,200 ordinary shares, par value $0.000125 per share (the “Ordinary Shares”) to Mars Capital Holding Corp. and its assignees (the “Sponsors”) as well the Purchaser’s officers, directors and other insiders prior to completion of its initial public offering (together with the Sponsors, the “Insiders”); and ii) for additional cash and for other potential funding the Sponsors may contribute toward the Purchaser’s working capital, entered into a promissory note with its Sponsors for $337,500 which upon closing of the Business Combination (the “Closing”) will automatically convert to 40,500 Ordinary Shares, resulting in the Insiders holding an aggregate of 2,510,700 Ordinary Shares on a fully converted basis at the Closing (“Insider Shares”); and

WHEREAS, in accordance with the terms of Section 10.11 of the Business Combination Agreement, the Parties desire to amend the Business Combination Agreement as set forth herein.

NOW, THEREFORE, in consideration of the foregoing and the respective covenants and agreements set forth below, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Parties agree as follows:

Section 1.    Amendments to the Business Combination Agreement.

1.8   Merger Consideration. The aggregate consideration to be paid to Company Holders pursuant to the Company Merger (the “Merger Consideration”) shall be a number of shares of Pubco Common Stock with an aggregate value equal to One Hundred Ten Million U.S. Dollars ($110,000,000) minus (or plus, if negative) the amount of the Closing Net Debt that exceeds of $20 million (for the avoidance of doubt, if the Closing Net Debt is $25 million, the adjustment shall be made by deducting $5 million from the Merger Consideration), with each Company Holder receiving for each Company Common LLC Unit held a number of shares of Pubco Common Stock equal to (a) the Per Unit Price, divided by (b) $9.87 (the “Conversion Ratio”) (as rounded down to the nearest whole number). Additionally, after the Closing, subject to the terms and conditions set forth in this Agreement, the Company Holder Participants shall have the contingent right to receive Earnout Shares from Pubco as additional consideration if the applicable Earnout Milestones as set forth in Section 1.10 are satisfied.

1.11(b) Purchaser Ordinary Shares. Every issued and outstanding Purchaser Ordinary Share (other than those described in Section 1.11(c), Section 1.11(d) and Section 1.11(e) below) that is not redeemed in the Closing Redemption shall become and be converted automatically at the Effective Time into the right to receive (i) one (1) share of Pubco Common Stock and (ii) one (1) share of Pubco Common Stock, or a convertible security automatically convertible or exercisable for one (1) share of Pubco Common Stock after 90 days following the Closing or such other period as may be agreed by the Purchaser and the Company and with such other terms as may be agreed by the Purchaser and the Company (together, the “Per Share Purchaser Merger Consideration”), following which, all Purchaser Ordinary Shares shall cease to be outstanding and shall automatically be canceled and shall cease to exist. The holders of any certificates previously evidencing Purchaser Ordinary Shares outstanding immediately prior to the Effective Time shall cease to have any rights with respect to such shares, except as provided herein or by Law. Any certificate previously evidencing Purchaser Ordinary Shares shall be exchanged for a certificate (if required by Law) representing the same number of shares of Pubco Common Stock upon the surrender of such certificate in accordance with Section 1.13. Any certificate formerly representing Purchaser Ordinary Shares (other those described in Section 1.10(d) and Section 1.11(e) below) shall thereafter represent only the right to receive the same number of shares of Pubco Common Stock. Insiders will hold an aggregate of 2,510,700 Ordinary Shares which include conversion of all rights held by the Insiders. It is hereby confirmed that the Insiders shall receive two shares of Pubco Common Stock for every Ordinary Share, or a total of 5,021,400 shares of Pubco Common Stock, under terms as provided for pursuant to this Section 1.11(b) of the Business Combination Agreement.”

“Insiders” mean Sponsor and its assignees, the Purchaser’s officers, directors and IPO Underwriter.

Section 2.    Effectiveness of Amendment. Upon the execution and delivery hereof, the Business Combination Agreement shall thereupon be deemed to be amended as hereinabove set forth as fully and with the same effect as if the amendments made hereby were originally set forth in the Business Combination Agreement, and this Amendment and the Business Combination Agreement shall henceforth respectively be read, taken and construed as one and the same instrument, but such amendments shall not operate so as to render invalid or improper any action heretofore taken under the Business Combination Agreement.

Section 3.    General Provisions.

(a)     Miscellaneous. This Amendment may be executed in two or more counterparts, each of which shall be deemed an original but all of which together shall be considered one and the same agreement and shall become effective when counterparts have been signed by each of the parties hereto and delivered to the other parties, it being understood that all parties need not sign the same counterpart. This Amendment may be executed and delivered by facsimile or PDF transmission.

(b)    Business Combination Agreement in Effect. Except as specifically provided for in this Amendment, the Business Combination Agreement shall remain unmodified and in full force and effect.

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IN WITNESS WHEREOF, each of the parties hereto has caused this Amendment to be executed as of the date first written above.

[Signature Page to Amendment No. 2 to Business Combination Agreement]

Exhibit 10.1

SUBSCRIPTION AGREEMENT

THIS SUBSCRIPTION AGREEMENT (this “Agreement”) is made and entered into effectively as of April 2, 2024 (the “Effective Date”), by, between and among Polar Multi-Strategy Master Fund (the “Investor”), Mars Acquisition Corp., a Cayman Islands exempted company (“SPAC”), Mars Capital Holdings Corporation, a British Virgin Islands business company (“Sponsor”), and Scantech Identification Beam Systems, LLC, a Delaware limited liability company (“Scantech”). Investor, SPAC, Sponsor and Scantech are referred to in this Agreement individually as a “Party” and collectively as the “Parties.”

WHEREAS, SPAC is a special purpose acquisition company that closed on its initial public offering on February 16, 2023, with 12 months to complete an initial business combination (the “De- SPAC”);

WHEREAS, on January 30, 2024, SPAC held a special meeting of stockholders during which SPAC’s stockholders approved a proposal to extend the date by which the SPAC must consummate the De- SPAC from February 16, 2024 to November 16, 2024; (the “Extension”);

WHEREAS, on September 5, 2023, SPAC entered a business combination agreement with Scantech (the “Business Combination Agreement”). The transactions contemplated by the Business Combination Agreement are hereinafter referred to collectively as the “Business Combination”;

WHEREAS, as of the date of this Agreement, SPAC has not completed the De-SPAC;

WHEREAS, Sponsor is seeking to raise funds from existing SPAC investors which will in turn be loaned by the Sponsor to the Scantech for working capital expenses (“Scantech Loan”);

WHEREAS, pursuant to the terms and conditions of this Agreement, Investor has agreed to fund an amount up to $1,000,000 to Sponsor (the “Capital Contribution”) in return for the Subscription Shares;

WHEREAS, Scantech will pay all principal under the Scantech Loan to Sponsor at the closing of the De-SPAC transaction (the “De-SPAC Closing”), in accordance with Section 1.5 below, and the Investor will be entitled to receive from the Sponsor an amount equal to the Capital Investment (as defined below) as a return of capital; and

NOW, THEREFORE, in consideration of the premises set forth above, which are incorporated in this Agreement as if fully set forth below, and the representations, warranties, covenants and agreement contained in this Agreement, and intending to be legally bound hereby, the Parties agree as follows:

ARTICLE I

SUBSCRIPTION AND RETURN OF CAPITAL

For greater certainty, Sponsor has the right but no obligation to request Capital Call(s) in its sole discretion, and no Capital Calls may be requested after the termination or expiry of this Agreement. All Capital Calls shall be funded by the Investor to the Sponsor within five (5) calendar days of receiving a Capital Notice except for the Initial Capital Call which shall be funded at Closing. Investor shall advance the Capital Call amount specified in the Capital Notice to the Sponsor by wire transfer of immediately available funds pursuant to the wiring instructions separately provided.

provided, in each case, that in no event will SPAC (or the surviving entity following the De-SPAC Closing) issue, any Default Shares to Investor that would result in Investor (together with any other persons whose beneficial ownership of SPAC’s Common Stock would be aggregated with Investor’s for purposes of Section 13(d) or Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the applicable regulations of the Securities and Exchange Commission, including any “group” of which Investor is a member) beneficially owning more than 19.9% of the outstanding shares of SPAC Common Stock (“Ownership Limit”); provided further than any Default Shares that were not issued to Investor because the issuance of such shares would have exceeded the Ownership Limit shall be promptly issued to Investor upon written request from Investor to extent that, at the time of such request, such issuance would no longer exceed the Ownership Limit. Any such Default Shares received pursuant to this Section 1.6 shall be subject to the Registration Requirement if a registration statement covering such shares is not effective at the time the Default Shares are transferred to Investor, and if a registration statement has been declared effective, such Default Shares shall be promptly registered, and in any event will be registered within 30 days. In the event that Investor notifies Sponsor and SPAC of any default pursuant to this Section 1.6, Sponsor shall not sell, transfer, or otherwise dispose of any SPAC securities owned by the Sponsor, other than in accordance with this Section 1.6, until such default is cured.

ARTICLE II

BCA TERMINATION

ARTICLE III
REPRESENTATIONS AND WARRANTIES

Each Party hereby represents and warrants to each other Party as of the date of this Agreement and as of each date that a Capital Call is funded hereunder that:

“THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED OR ANY STATE SECURITIES ACT. THE SECURITIES HAVE BEEN ACQUIRED FOR INVESTMENT AND MAY NOT BE SOLD, TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS (I) THEY SHALL HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY APPLICABLE STATE SECURITIES ACT, OR (II) AN EXEMPTION FROM THE REGISTRATION REQUIREMENTS UNDER THE SECURITIES ACT OF 1933, AS AMENDED, EXISTS..”

The SPAC shall take all steps necessary in order to remove the legend referenced in the preceding paragraph from the Investor Shares immediately following the earlier of (a) the effectiveness of a registration statement applicable to the Investor Shares or (b) any other applicable exception to the restrictions described in the legend occurs.

ARTICLE IV
MISCELLANEOUS

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The Parties have caused this Agreement to be duly executed and delivered, all as of the date first set forth above.

Exhibit 10.2

THIS PROMISSORY NOTE (“NOTE”) HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”). THIS NOTE HAS BEEN ACQUIRED FOR INVESTMENT ONLY AND MAY NOT BE SOLD, TRANSFERRED OR ASSIGNED IN THE ABSENCE OF REGISTRATION OF THE RESALE THEREOF UNDER THE SECURITIES ACT OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY IN FORM, SCOPE AND SUBSTANCE TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.

CONVERTABLE PROMISSORY NOTE

Mars Acquisition Corp., an exempted limited liability Cayman Islands company and blank check company (the “Maker”), promises to pay to the order of Mars Capital Holding Corporation and its assignees (the “Payee”), or order, the principal sum of Three Hundred and Thirty Seven Thousand and Five Hundred Dollars ($337,500), in lawful money of the United States of America, on the terms and conditions described below. All payments on this Note shall be made by check or wire transfer of immediately available funds or as otherwise determined by the Maker to such account as the Payee may from time to time designate by written notice in accordance with the provisions of this Note.

1. Principal. The principal balance of this Note shall be payable by the Maker on the date on which Maker consummates the business combination with ScanTech Identification Beam Systems, LLC (the “Business Combination”), or the date of consummation of a business combination with another target, whichever is later, such later date is referred to as the “Maturity Date.”

2. Repayment. The principal balance may be prepaid at any time. Under no circumstances shall any individual, including but not limited to any officer, director, employee or shareholder of the Maker, be obligated personally for any obligations or liabilities of the Maker hereunder.

4. Interest. No interest shall accrue on the unpaid principal balance of this Note.

4. Conversion. The principal balance will automatically convert into 40,500 ordinary shares of the Maker on the Maturity Date.

5. Waiver. In the event that no business combination occurs between the Maker and any third party, the obligation to repay the Note shall be waived.

6. Events of Default. The following shall constitute an event of default (“Event of Default”):

(a) Voluntary Bankruptcy, Etc. The commencement by Maker of a voluntary case under any applicable bankruptcy, insolvency, reorganization, rehabilitation or other similar law, or the consent by it to the appointment of or taking possession by a receiver, liquidator, assignee, trustee, custodian, sequestrator (or other similar official) of Maker or for any substantial part of its property, or the making by it of any assignment for the benefit of creditors, or the failure of Maker generally to pay its debts as such debts become due, or the taking of corporate action by Maker in furtherance of any of the foregoing. 

(b) Involuntary Bankruptcy, Etc. The entry of a decree or order for relief by a court having jurisdiction in the premises in respect of Maker in an involuntary case under any applicable bankruptcy, insolvency or other similar law, or appointing a receiver, liquidator, assignee, custodian, trustee, sequestrator (or similar official) of Maker or for any substantial part of its property, or ordering the winding-up or liquidation of its affairs, and the continuance of any such decree or order unstayed and in effect for a period of 60 consecutive days.

7. Notices. All notices, statements or other documents which are required or contemplated by this Note shall be made in writing and delivered: (i) personally or sent by first class registered or certified mail, overnight courier service or facsimile or electronic transmission to the address designated in writing, (ii) by facsimile to the number most recently provided to such party or such other address or fax number as may be designated in writing by such party or (iii) by electronic mail, to the electronic mail address most recently provided to such party or such other electronic mail address as may be designated in writing by such party. Any notice or other communication so transmitted shall be deemed to have been given on the day of delivery, if delivered personally, on the business day following receipt of written confirmation, if sent by facsimile or electronic transmission, one (1) business day after delivery to an overnight courier service or five (5) days after mailing if sent by mail.

8. Construction. THIS NOTE SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF NEW YORK, WITHOUT REGARD TO CONFLICT OF LAW PROVISIONS THEREOF.

9. Severability. Any provision contained in this Note which is prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining provisions hereof, and any such prohibition or unenforceability in any jurisdiction shall not invalidate or render unenforceable such provision in any other jurisdiction.

10. Trust Waiver. Notwithstanding anything herein to the contrary, the Payee hereby waives any and all right, title, interest or claim of any kind (“Claim”) in or to any distribution of or from the trust account in which the proceeds of the Maker’s initial public offering were deposited, and hereby agrees not to seek recourse, reimbursement, payment or satisfaction for any Claim against the trust account for any reason whatsoever.

11. Amendment; Waiver. Any amendment hereto or waiver of any provision hereof may be made with, and only with, the written consent of the Maker and the Payee.

12. Assignment. No assignment or transfer of this Note or any rights or obligations hereunder may be made by any party hereto (by operation of law or otherwise) without the prior written consent of the other party hereto and any attempted assignment without the required consent shall be void.

IN WITNESS WHEREOF, Maker, intending to be legally bound hereby, has caused this Note to be duly executed by the undersigned as of the day and year first above written.