Nature of Operations	6 Months Ended
Nature of Operations	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Note 1. Nature of Operations The Company Momentus Inc. (together with its consolidated subsidiaries “Momentus” or the “Company”) is a U.S. commercial space company that offers in-space infrastructure services, including in-space transportation, hosted payloads and in-orbit services. Momentus is making new ways of operating in space possible with its in-space transfer and service vehicles, powered by an innovative, space-proven water plasma-based propulsion system. On May 25, 2022, the Company launched its Vigoride 3 Orbital Service Vehicle (OSV) to low-earth orbit aboard the SpaceX Transporter-5 mission. In addition to Vigoride 3, Momentus used a second port on the same SpaceX mission to fly a third-party deployer from a partner company. Momentus deployed a total of eight customer satellites in low-earth orbit during its inaugural mission, comprising seven satellites from Vigoride 3 and one satellite from the third-party deployer system. The Company incorporated improvements identified during its inaugural mission in advance of its first follow-on mission and other planned follow-on missions. On January 3, 2023, the Company launched its Vigoride 5 OSV to low-earth orbit aboard the SpaceX Transporter-6 mission. The mission is ongoing and the Vigoride 5 OSV is maneuvering under its own power in low-earth orbit. The primary mission objective is to test the spacecraft on orbit, learn from any issues that are encountered and implement lessons-learned on future Vigoride vehicles and missions. The mission also supported two customers: the Qosmosys Zeus-1 payload which was deployed on orbit on May 10, 2023, and Caltech’s Space Solar Power Demonstrator project, a hosted payload for which the Vigoride 5 continues to provide thrusting maneuvers and on-orbit support, including providing data, communication, commanding and telemetry, and resources for optimal picture taking and solar cell lighting. As part of the Vigoride 5 mission, we successfully completed the initial tests on-orbit of the pioneering Microwave Electrothermal Thruster (MET) that relies on solar power and uses distilled water as a propellant. The MET is the Vigoride OSV’s primary propulsion method that produces thrust by expelling extremely hot gases through a rocket nozzle. Unlike a conventional chemical rocket engine, which creates thrust through a chemical reaction, the MET is designed to create a plasma and thrust using solar power to drive a microwave energy source that heats the water propellant. Momentus has two patents in support of this proprietary propulsion technology. The recent MET testing done on-orbit included dozens of firings of the thruster that imparted forces on the Vigoride 5 spacecraft. These forces can change the orbital velocity of the spacecraft, allowing the orbit to be adjusted, changing parameters such as altitude and orbital inclination. This capability allows Momentus to deliver its customers’ payloads to custom orbits. Momentus has used the MET to change the spacecraft altitude during the current Vigoride 5 mission. The Vigoride OSV’s Attitude Control and Reaction Control Systems also use water as a propellant and were recently tested and fully commissioned. With its water-based propulsion systems, Momentus aims to offer cost-effective, efficient, safe, and environmentally friendly propulsion to meet the demands for in-space transportation and infrastructure services. On April 15, 2023, the Company launched its Vigoride 6 OSV to low-earth orbit aboard the SpaceX Transporter-7 mission and used its MET to change the orbital inclination of the Vigoride 6 OSV to support the deliveries of six customer payloads, including two satellites for the NASA LLITED mission. The Vigoride 6 mission is also hosting a Momentus technology demonstration of a new kind of solar array. The Tape Spring Solar Array (TASSA) technology features large sheets of flexible solar cells bonded to tape springs. To stow, they are tightly coiled around a mandrel. After launch, motors unroll the mandrel, deploying the solar array. Momentus aims to drive down vehicle production costs and streamline on-orbit operations, while reducing the cost of power for the satellite, with this technology once operational. Momentus has entered a new phase by operating two spacecraft in orbit concurrently as the Company continues to grow its capabilities. The Company anticipates flying its next mission with its Vigoride OSV in early 2024. All future missions remain subject to the receipt of licenses and government approvals, and the successful completion of our efforts to prepare our spacecraft for flight. The Company can offer no assurances that the vehicles that it plans to operate in the future missions will be ready on time, or that they will operate as intended. Business Combination On August 12, 2021, the Company consummated a merger pursuant to certain Agreement and Plan of Merger, dated October 7, 2020, and as amended on March 5, 2021, April 6, 2021, and June 29, 2021 (the “Merger Agreement”), by and among Stable Road Acquisition Corp (“SRAC”), Project Marvel First Merger Sub, Inc., a Delaware corporation and a direct, wholly owned subsidiary of SRAC (“First Merger Sub”), and Project Marvel Second Merger Sub, LLC, a Delaware limited liability company and a direct, wholly owned subsidiary of SRAC (“Second Merger Sub”), pursuant to which First Merger Sub merged with and into Momentus Inc., a Delaware corporation (“Legacy Momentus”) with Legacy Momentus as the surviving corporation of the First Merger Sub, and immediately following which Legacy Momentus merged with and into the Second Merger Sub, with the Second Merger Sub as the surviving entity (the “Business Combination”). In connection with the closing of the Business Combination (“Closing”), the Company changed its name from Stable Road Acquisition Corp. to Momentus Inc., and Legacy Momentus changed its name to Momentus Space, LLC. The Business Combination was accounted for as a reverse recapitalization under ASC 805, Business Combinations, with SRAC and its two wholly owned subsidiaries. The Company received gross proceeds of $247.3 million upon the closing of the Business Combination. Public and private warrants of SRAC were assumed by the Company as a result of the Business Combination. Going Concern The accompanying financial statements have been prepared assuming that the Company will continue as a going concern. The going concern basis of presentation assumes that the Company will continue in operation one year after the date these unaudited condensed consolidated interim financial statements are issued and will be able to realize its assets and discharge its liabilities and commitments in the normal course of business. The Company’s ability to continue as a going concern is dependent on the Company’s ability to successfully raise capital to fund its business operations and execute on its business plan. To date the Company remains heavily focused on growth and continued development of its proprietary technology, as a result of this it has not generated sufficient revenues to provide cash flows that enable the Company to finance its operations internally and the Company’s financial position and operating results raise substantial doubt about the Company’s ability to continue as a going concern. This is reflected by the Company’s incurred net losses of $18.8 million and $39.7 million for the three and six months ended June 30, 2023, respectively, and accumulated deficit of $343.8 million as of June 30, 2023. Additionally, the Company used net cash of $33.2 million to fund its operating activities for the six months ended June 30, 2023, and had cash and cash equivalents of $21.3 million as of June 30, 2023. Pursuant to the requirements of ASC Topic 205-40, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, management must evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern for one year from the date these unaudited condensed consolidated interim financial statements are issued. This evaluation does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented or are not within control of the Company as of the date the unaudited condensed consolidated interim financial statements are issued. When substantial doubt exists, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the unaudited condensed consolidated Interim financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the unaudited condensed consolidated interim financial statements are issued. In connection with the preparation of the condensed consolidated financial statements for the three and six months ended June 30, 2023, management conducted an evaluation and concluded that there were conditions and events, considered in the aggregate, which raised substantial doubt as to the Company’s ability to continue as a going concern within twelve months after the date of the issuance of such financial statements. The Company believes that its current level of cash and cash equivalents are not sufficient to fund its regular operations and commercial scale production and sale of its services and products. These conditions raise substantial doubt regarding its ability to continue as a going concern for a period of at least one year from the date of issuance of these unaudited condensed consolidated financial statements. In order to proceed with the Company’s business plan and operating strategy, the Company will need to raise substantial additional capital to fund its operations. Until such time, if ever, the Company can generate revenues sufficient to achieve profitability, the Company expects to finance its operations through equity or debt financings, which may not be available to the Company on the timing needed or on terms that the Company deems to be favorable. In an effort to alleviate these conditions, the Company has recently executed a term sheet to raise capital with Deutsche Bank and continues to seek and evaluate all opportunities to access additional capital through any available means. As a result of these uncertainties, and notwithstanding management’s plans and efforts to date, there is substantial doubt about the Company’s ability to continue as a going concern. If the Company is unable to raise substantial additional capital in the near term, the Company's operations and business plan will need to be scaled back or halted altogether. Additionally, if the Company is able to raise additional capital but that capital is insufficient to provide a bridge to full commercial production at a profit, the Company's operations could be severely curtailed or cease entirely and the Company may not realize any significant value from its assets. The accompanying condensed consolidated financial statements have been prepared on a going concern basis of accounting. The accompanying condensed consolidated financial statements do not reflect any adjustments that might result if the Company is unable to continue as a going concern.