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        <entity>
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        <period>
            <startDate>2026-06-18</startDate>
            <endDate>2026-06-18</endDate>
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    <context id="c20260618to20260618_StatementClassOfStockAxis_WarrantsMember">
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        <period>
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            <endDate>2026-06-18</endDate>
        </period>
    </context>
    <dei:AmendmentFlag
      contextRef="c20260618to20260618"
      id="Fact_c6d57522bc7642619362e0136c95920f">false</dei:AmendmentFlag>
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      contextRef="c20260618to20260618"
      id="Fact_3d6da6b41f7c4a328849072cdd762ab7">0001781162</dei:EntityCentralIndexKey>
    <dei:DocumentType
      contextRef="c20260618to20260618"
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      contextRef="c20260618to20260618"
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      contextRef="c20260618to20260618"
      id="Fact_51c6f3abbfc4497bb4568cf9be1dcf91">Momentus Inc.</dei:EntityRegistrantName>
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      contextRef="c20260618to20260618"
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      contextRef="c20260618to20260618"
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      id="Fact_01037813b36746fe87c2285549de1619">650</dei:CityAreaCode>
    <dei:LocalPhoneNumber
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      contextRef="c20260618to20260618"
      id="Fact_fd16d7ddd7cb45739047ccfd3e69a347">false</dei:WrittenCommunications>
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    <dei:SecurityExchangeName
      contextRef="c20260618to20260618_StatementClassOfStockAxis_CommonClassAMember"
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      contextRef="c20260618to20260618_StatementClassOfStockAxis_WarrantsMember"
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    <dei:TradingSymbol
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