EXHIBIT A
                            JOINT FILING AGREEMENT

Pursuant to Rule 13d-1(k)(1) promulgated under the Securities Exchange Act of
1934, the undersigned agree to the joint filing of a Statement on Schedule 13G
(including any and all amendments thereto, and any filing on Schedule 13D
relating to the same investment) with respect to the shares of common stock,
par value $0.01 per share, of Capstone Turbine Corporation, and further agree
that this Joint Filing Agreement be included as an Exhibit thereto.  In
addition, each party to this Agreement expressly authorizes each other party
to this Agreement to file on its behalf any and all amendments to such
Statement.

Dated: June 13, 2005.


RHO CAPITAL PARTNERS, INC.

    By: /s/ Jeffrey I. Martin
    ------------------------------------
    Jeffrey I. Martin, Authorized Signer



RHO MANAGEMENT TRUST I
By: RHO CAPITAL PARTNERS, INC.
    as Investment Adviser

    By: /s/ Jeffrey I. Martin
    ------------------------------------
    Jeffrey I. Martin, Authorized Signer


/s/ Jeffrey I. Martin
- ------------------------------------------------------
Jeffrey I. Martin, Authorized Signer for Joshua Ruch



/s/ Jeffrey I. Martin
- ------------------------------------------------------
Jeffrey I. Martin, Authorized Signer for Habib Kairouz



/s/ Jeffrey I. Martin
- ------------------------------------------------------
Jeffrey I. Martin, Authorized Signer for Mark Leschly