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                           March 23, 2021

       Donald R. Young
       Chief Executive Officer
       Aspen Aerogels, Inc.
       30 Forbes Road, Building B
       Northborough, MA 01532

                                                        Re: Aspen Aerogels,
Inc.
                                                            Registration
Statement on Form S-3
                                                            Filed March 15,
2021
                                                            File No. 333-254250

       Dear Mr. Young:

              This is to advise you that we have not reviewed and will not
review your registration
       statement.

               Please refer to Rules 460 and 461 regarding requests for
acceleration. We remind you
       that the company and its management are responsible for the accuracy and
adequacy of their
       disclosures, notwithstanding any review, comments, action or absence of
action by the staff.

                                                        Please contact Donald
Field at 202-551-3680 with any questions.




                           Sincerely,


                           Division of Corporation Finance

                           Office of Trade & Services