<PAGE>

                                                                     Exhibit 4.4

                               AMENDMENT NO. 2 TO

                          REGISTRATION RIGHTS AGREEMENT

                                February 28, 2000



To each of the Purchasers named in
Schedule I to the Series C Convertible
Preferred Stock Purchase Agreement
dated February 28, 2000 (the "Purchasers")


Ladies and Gentlemen:

     On June 4, 1998, Cidera, Inc. (formerly SkyCache, Inc.), a Delaware
corporation (the "Company"), Douglas E. Humphrey, Lisa Losito, each of the
several purchasers listed on Schedule I to that certain Series A Convertible
Preferred Stock Purchase Agreement of even date therewith, Anchor Financial
Group LLC, and the holders of the Warrants to Purchase shares of the Common
Stock, $.01 par value, of the Company issued pursuant to that certain Bridge
Financing Agreement dated February 16, 1998, entered into a Registration Rights
Agreement (as amended, the "Agreement") of even date therewith. On June 9, 1999,
the parties to the Agreement entered into Amendment No. 1 to the Agreement along
with the several purchasers listed on Schedule I to that certain Series B
Convertible Preferred Stock Purchase Agreement of even date with such Amendment
No. 1.

     The parties to the Agreement now wish to further amend the Agreement to
extend the rights and benefits thereof to holders of Series C Convertible
Preferred Stock, $.01 par value, of the Company (the "Series C Preferred Stock")
issued pursuant to that certain Series C Convertible Preferred Stock Purchase
Agreement of even date herewith (the "Series C Stock Purchase Agreement") by and
among the Company and the Purchasers and to make certain other changes as
hereinafter set forth.

     Section 13(d) of the Agreement provides for such Agreement to be amended
both with the written consent of the Company and the holders of at least
two-thirds of the outstanding shares of Restricted Stock (as defined therein).

     In consideration of and pursuant to the foregoing, the Company covenants
and agrees with each of you that the Agreement is hereby amended as follows:

     1.   All of the shares of Series C Preferred Stock purchased pursuant to
          the Series C Stock Purchase Agreement shall be "Preferred Shares" for
          all purposes and to the same extent as if they were originally
          included as "Preferred Shares"
<PAGE>

          under the Agreement, all references in the Agreement to the "Preferred
          Stock" and the "Purchase Agreement" shall include all of the shares of
          such Series C Preferred Stock and the Series C Stock Purchase
          Agreement, respectively and all references in the Agreement to
          "Purchasers" shall include each Purchaser named in Schedule I to the
          Series C Stock Purchase Agreement.

     2.   Section 4(b) of the Agreement is hereby amended by adding the
          following sentence:

          "Notwithstanding anything to the contrary contained herein, in the
          event that the holders of 33% or more of the then outstanding shares
          of Series C Preferred Stock (or Conversion Shares relating thereto)
          elect not to include their shares of Restricted Stock in at least one
          registration pursuant to this Section 4, such holders will be entitled
          to require the Company to effect two additional registrations pursuant
          to this Section 4, which registrations may be requested by a holder or
          holders of at least 30% of the total shares of Series C Convertible
          Preferred Stock of the Company then outstanding."

     3.   Section 4 of the Agreement is hereby amended by replacing "50%" in the
          fourth line thereof with "30%."

     4.   With respect to registrations on Form S-3, Section 6 of the Agreement
          is hereby amended by replacing "50%" in the second line thereof and
          replacing it with "20%."

     5.   Section 9(d) of the Agreement is hereby amended by replacing:
          "provided, however, that, in any such case, (A) no such holder will be
           --------  -------
          required to contribute any amount in excess of the public offering
          price of all such Restricted Stock, Warrant Shares or Founders' Stock
          offered by it pursuant to such registration statement;" beginning in
          the sixteenth line, with: "provided, however, that, in any such case,
                                     --------  -------
          (A) no such holder will be required to contribute any amount in excess
          of the net proceeds received by such holder for all such Restricted
          Stock, Warrant Shares or Founders' Stock offered by it pursuant to
          such registration statement;".

     6.   Section 13(c) of the Agreement is hereby amended to replace the word
          "Maryland" with the word "Delaware." The following additional language
          is hereby added to such Section 13(c): "Each of the parties hereby
          submits to
<PAGE>

          personal jurisdiction and waives any objection as to venue in the
          State of Delaware. Service of process on the parties in any action
          arising out of or relating to this Agreement shall be effective if
          provided in accordance with Section 13(b). The parties hereby waive
          all right to trial by jury in any action or proceeding to enforce or
          defend any rights under this Agreement."

     7.   Section 13(d) of the Agreement is hereby amended by adding the
          following sentence:

          "Notwithstanding anything to the contrary in this Agreement, the
          provisions of Section 4(b) hereof shall not be amended without the
          consent of holders of at least two-thirds of the outstanding shares of
          the Series C Preferred Stock."

     This Amendment may be executed in two or more counterparts, each of which
shall be deemed an original, but all of which together shall constitute one and
the same instrument. This Amendment shall be effective upon execution by the
Company and the holders of at least two-thirds of the outstanding shares of
Restricted Stock (as defined in the Agreement).

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]
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     Please indicate your acceptance of the foregoing by signing and returning
the enclosed counterpart of this letter, whereupon this Agreement shall be a
binding agreement between the Company and you.

                                   Very truly yours,

                                   CIDERA, INC.



                                          By: /s/ Douglas E. Humphrey
                                              ---------------------------------
                                                  Douglas E. Humphrey
                                                  President and Chief Executive
                                                  Officer

AGREED TO AND ACCEPTED as of the
date first above written.

CARLYLE VENTURE PARTNERS, L.P.

By: Its General Partner, TCG Ventures, Ltd.


By: /s/ J. Mitchell Reese
   -----------------------------
        J. Mitchell Reese
        Attorney in Fact


C/S Venture INVESTORS, L.P.

By: Its General Partner, TCG Ventures, Ltd.

By: /s/ J. Mitchell Reese
   -----------------------------
        J. Mitchell Reese
        Attorney in Fact


Carlyle U.S. Venture Partners, L.P.

By: Its General Partner, TCG Ventures, L.L.C.

By: /s/ J. Mitchell Reese
   -----------------------------
        J. Mitchell Reese
        Managing Director

                      [SIGNATURE PAGE TO AMENDMENT NO. 2
                       TO REGISTRATION RIGHTS AGREEMENT]
<PAGE>

Carlyle Venture Coinvestment, L.L.C.

By: Its Manager, TCG Ventures, L.L.C.

By: /s/ J. Mitchell Reese
   -----------------------------
        J. Mitchell Reese
        Managing Director

/s/ Douglas E. Humphrey
-----------------------
Douglas E. Humphrey


/s/ Lisa Losito
---------------
Lisa Losito


NEW ENTERPRISE ASSOCIATES VIII,
LIMITED PARTNERSHIP

By:  NEA Partners VIII, Limited Partnership
     General Partner


      By: /s/ Peter Barris
         -----------------
         General Partner

NEA PRESIDENTS' FUND, L.P.

By:   NEA General Partners, L.P.
      General Partner


      By: /s/ Peter Barris
         -----------------
          General Partner

NEA VENTURES 1999, L.P.


      By: /s/ Peter Barris
         -----------------
          General Partner

                      [SIGNATURE PAGE TO AMENDMENT NO. 2
                       TO REGISTRATION RIGHTS AGREEMENT]
<PAGE>

INSTITUTIONAL VENTURE PARTNERS VIII, L.P.

By:  its General Partner, Institutional Venture Management VIII, LLC


      By: /s/ R. Thomas Dyal
         -----------------------------------
          R. Thomas Dyal, Managing Director

IVM INVESTMENT FUND VIII, LLC

By:  its Manager Institutional Venture Management VIII, LLC


      By: /s/ R. Thomas Dyal
         -----------------------------------
          R. Thomas Dyal, Managing Director


IVP BROADBAND FUND, L.P.

By:  its General Partner IVP Broadband Management, LLC
By:  its Managing Director, Institutional Venture Management VIII, LLC


      By: /s/ R. Thomas Dyal
         -----------------------------------
          R. Thomas Dyal, Managing Director

INTEL CORPORATION


By: Noel Lazo
    ---------
Its: Assistant Treasurer
     -------------------

PURCHASERS NOT PREVIOUSLY PARTY TO THE
AGREEMENT


GE CAPITAL EQUITY INVESTMENTS, INC.

By:/s/ Steven D. Smith
   -------------------
Name: Steven D. Smith
      ---------------
Title: Managing Director
       -----------------

                      [SIGNATURE PAGE TO AMENDMENT NO. 2
                       TO REGISTRATION RIGHTS AGREEMENT]
<PAGE>

INVESTOR (GUERNSEY) LTD.

By: /s/ David Jeffreys  Marc Hollander
    ----------------------------------
Name: David Jeffreys   Marc Hollander
      --------------------------------
Title:
      --------------------------------

DELL USA, L.P.
By: Dell Gen. P. Corp., its general partner

By: /s/ Alex C. Smith
    -----------------
Name: Alex C. Smith
      ---------------
Title: Vice President
       --------------

PSINET STRATEGIC INVESTMENTS, INC.

By: /s/ Harold S. Wills
    -------------------
Name: Harold S. Wills
      -----------------
Title: V.P. PSINet Strategic Investments, Inc.
       ---------------------------------------


/s/ Edward Postal
-----------------
Edward Postal


/s/ Thom F. Degnan   Diane H. Degnan
------------------------------------
Thom F. and Diane H. Degnan, JTWROS


/s/ Diane H. Degnan
-------------------
Diane H. Degnan,
         as custodian for Jamie Degnan


/s/ Diane H. Degnan
-------------------
Diane H. Degnan,
         as custodian for Todd Degnan

/s/ John Landry
-------------------------------------
John Landry

                      [SIGNATURE PAGE TO AMENDMENT NO. 2
                       TO REGISTRATION RIGHTS AGREEMENT]
<PAGE>

/s/ John Landry, as custodian for Jillian K. Landry
---------------------------------------------------
John Landry,
         as custodian for Jillian K. Landry



/s/ Adam Landry
---------------
Adam J. Landry

MCI WORLDCOM VENTURE FUND, INC.


By: /s/ Susan Mayer
   -----------------------
Name: Susan Mayer
     ---------------------
Title: President
      --------------------

 /s/ John Sidmore
--------------------------
John Sidgmore

/s/ Arno Penzias
--------------------------
Arno Penzias

/s/ Wayne Correia
--------------------------
Wayne Correia

                      [SIGNATURE PAGE TO AMENDMENT NO. 2
                       TO REGISTRATION RIGHTS AGREEMENT]