<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:ns2="http://www.sec.gov/edgar/common">
    <headerData>
        <submissionType>144</submissionType>
        <filerInfo>
            <filer>
                <filerCredentials>
                    <cik>0001920996</cik>
                    <ccc>XXXXXXXX</ccc>
                </filerCredentials>
            </filer>
            <liveTestFlag>LIVE</liveTestFlag>



        </filerInfo>
    </headerData>
    <formData>
        <issuerInfo>
            <issuerCik>0001145986</issuerCik>
            <issuerName>ASPEN AEROGELS, INC.</issuerName>
            <secFileNumber>001-36481</secFileNumber>
            <issuerAddress>
                <ns2:street1>30 FORBES ROAD, BUILDING B</ns2:street1>
                <ns2:city>NORTHBOROUGH</ns2:city>
                <ns2:stateOrCountry>MA</ns2:stateOrCountry>
                <ns2:zipCode>01532</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>5086911111</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>RICARDO RODRIGUEZ</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Officer</relationshipToIssuer>
            </relationshipsToIssuer>
        </issuerInfo>
        <securitiesInformation>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>8th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>32465</noOfUnitsSold>
            <aggregateMarketValue>978495.10</aggregateMarketValue>
            <noOfUnitsOutstanding>77082075</noOfUnitsOutstanding>
            <approxSaleDate>08/26/2024</approxSaleDate>
            <securitiesExchangeName>NYSE</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>02/25/2023</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted Stock Units</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>7165</amountOfSecuritiesAcquired>
            <paymentDate>02/25/2023</paymentDate>
            <natureOfPayment>N/A</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>08/26/2024</acquiredDate>
            <natureOfAcquisitionTransaction>Exercise of Stock Options</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>25300</amountOfSecuritiesAcquired>
            <paymentDate>08/26/2024</paymentDate>
            <natureOfPayment>Cash</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <remarks>The securities to be sold were acquired upon the vesting of restricted stock units during the period of 02/23/2023 through 03/08/2024
The securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale.
</remarks>
        <noticeSignature>
            <noticeDate>08/26/2024</noticeDate>
            <planAdoptionDates>
                <planAdoptionDate>05/16/2024</planAdoptionDate>
            </planAdoptionDates>
            <signature>/s/ Ricardo C. Rodriguez</signature>
        </noticeSignature>
    </formData>
</edgarSubmission>
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144
0001920996
XXXXXXXX
LIVE
0001145986
ASPEN AEROGELS, INC.
001-36481
30 FORBES ROAD, BUILDING B
NORTHBOROUGH
MA
01532
5086911111
RICARDO RODRIGUEZ
Officer
Common
Morgan Stanley Smith Barney LLC Executive Financial Services
1 New York Plaza
8th Floor
New York
NY
10004
32465
978495.10
77082075
08/26/2024
NYSE
Common
02/25/2023
Restricted Stock Units
Issuer
N
7165
02/25/2023
N/A
Common
08/26/2024
Exercise of Stock Options
Issuer
N
25300
08/26/2024
Cash
Y
The securities to be sold were acquired upon the vesting of restricted stock units during the period of 02/23/2023 through 03/08/2024
The securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale.
08/26/2024
05/16/2024
/s/ Ricardo C. Rodriguez