Document:

<PAGE>   1
                                                                     EXHIBIT 4.7

                                                                  EXECUTION COPY

            SECOND AMENDMENT, dated as of February 16, 2000 (this "Amendment"),
to the Amended and Restated Credit Agreement, dated as of February 23, 1998, as
amended by the First Amendment dated as of June 23, 1998 (as the same may be
further amended, supplemented or otherwise modified from time to time, the
"Credit Agreement"), among FIRMAMENTO MEXICANO S. de R.L. de C.V., a limited
liability company (sociedad de responsabilidad limitada de capital variable)
organized under the laws of the United Mexican States ("Holdings"), SERVICIOS
CORPORATIVOS SATELITALES S.A. de C.V., a corporation (sociedad anonima de
capital variable) organized under the laws of the United Mexican States
("Mezzanine HoldCo"), SATELITES MEXICANOS, S.A. de C.V., a corporation (sociedad
anonima de capital variable) organized under the laws of the United Mexican
States ("Borrower"), the several banks and other financial institutions or
entities from time to time parties to this Agreement ("Lenders"), DONALDSON,
LUFKIN & JENRETTE SECURITIES CORPORATION and LEHMAN BROTHERS INC., as advisors
and arrangers (in such capacity, the "Arrangers"), DLJ CAPITAL FUNDING, INC. and
LEHMAN COMMERCIAL PAPER INC., as syndication agents (in such capacity, the
"Syndication Agents") and CITIBANK, N.A., as administrative agent (in such
capacity, the "Administrative Agent").

                              W I T N E S S E T H:

            WHEREAS, pursuant to the Credit Agreement, the Lenders have agreed
to make, and have made, certain loans and other extensions of credit to the
Borrower; and

            WHEREAS, the Borrower has requested, and, upon this Amendment
becoming effective, the Requisite Aggregate Lenders have agreed, that certain
provisions of the Credit Agreement be amended in the manner provided for in this
Amendment.

            NOW, THEREFORE, the parties hereto hereby agree as follows:

            1  Defined Terms.  Terms defined in the Credit Agreement and used
herein shall have the meanings given to them in the Credit Agreement.

            2. Amendment to Section 6.5 of the Credit Agreement. The sixth
sentence of Section 6.5 of the Credit Agreement is hereby amended by deleting
the sentence in its entirety and replacing it by two new sentences to read as
follows:

            "If a loss of an insured satellite occurs, the Borrower shall
            deposit with the Collateral Trustee a portion of the insurance
            proceeds from such loss, as cash collateral for the Secured
            Facilities. The amount of such cash collateral shall be at least
            $25,000,000 and shall be held in the Insurance Proceeds Debt Service
            Sub-Account (as defined in the Collateral Trust Agreement), subject
            to release to pay debt service to the extent requested by the
            Borrower in amounts not to exceed, in any period, the amount of
            revenue lost during such period by reason of the loss of such
            satellite (as such revenue loss is reasonably estimated by the
            Borrower and certified by the Borrower in writing)."

<PAGE>   2
                                                                               2

            3. Amendment to Subsection 7.1(a) of the Credit Agreement.
Subsection 7.1(a) of the Credit Agreement is hereby amended by amending and
restating in its entirety the grid for the Consolidated Leverage Ratio contained
in such subsection to read as follows:

<TABLE>
<CAPTION>
                          Each Fiscal Quarter                                       Consolidated
                          Ending During Period                                      Leverage Ratio
                          --------------------                                      --------------
<S>                                                                                <C>
                        December 31, 1999 to September 30, 2000                     7.50:1.00
                        December 31, 2000 to June, 30 2001                          7.25:1.00
                        September 30, 2001 to December 31, 2001                     7.00:1.00
                        March 31, 2002 to June 30, 2002                             6.75:1.00
                        September 30, 2002 to December 31, 2002                     6.50:1.00
                        March 31, 2003                                              6.25:1.00
                        June 30, 2003                                               6.00:1.00
                        September 30, 2003 to December 31, 2003                     5.50:1.00
                        March 31, 2004 and thereafter                               5.00:1.00
</TABLE>

            4. Amendment to Subsection 7.1(b) of the Credit Agreement.
Subsection 7.1(b) of the Credit Agreement is hereby amended by amending and
restating in its entirety the grid for the Consolidated Interest Coverage Ratio
contained in such subsection to read as follows:

<TABLE>
<CAPTION>
                          Each Fiscal Quarter                                       Consolidated Interest
                          Ending During Period                                      Coverage Ratio
                          --------------------                                      --------------
<S>                                                                             <C>
                        December 31, 1999 to September 30, 2000                     1.20:1.00
                        December 31, 2000 to June 30, 2001                          1.25:1.00
                        September 30, 2001 to June 30, 2002                         1.35:1.00
                        September 30, 2002 to December 31, 2002                     1.45:1.00
                        March 31, 2003                                              1.50:1.00
                        June 30, 2003                                               1.60:1.00
                        September 30, 2003                                          1.70:1.00
                        December 31, 2003                                           1.80:1.00
                        March 31, 2004                                              1.90:1.00
                        June 30, 2004                                               2.00:1.00
                        September 30, 2004 and thereafter                           2.25:1.00
</TABLE>

            5. Amendment of Annex A to the Credit Agreement. Annex A to the
Credit Agreement is hereby amended by (i) deleting from the header relating to
the pricing grid for Tranche A Term Loans and Revolving Credit Loans the words
"and Revolving Credit Loans" with the effect that such pricing grid shall be
applicable only to Tranche A Term Loans and (ii) inserting a new pricing grid
applicable to Revolving Credit Loans to read as follows:

               Revolving Credit Loans:

<PAGE>   3
                                                                               3

<TABLE>
<CAPTION>
                        Consolidated            Applicable Margin-                  Applicable Margin-
                        Leverage Ratio          Eurodollar Loans [*]                Base Rate Loans [*]
                        --------------          --------------------                -------------------
<S>                                            <C>                                 <C>
                        >  6.00 to 1.00               4.25%                              3.25%
                        >  5.00 to 1.00               3.75%                              2.75%
                        >  4.00 to 1.00               3.00%                              2.00%
                        [ ] 4.00 to 1.00              2.50%                              1.50%
</TABLE>

            6. Conditions to Effectiveness. This Amendment shall become
effective on the date (the "Amendment Effective Date") on which all of the
following conditions precedent have been satisfied or waived:

            (a) The Requisite Aggregate Lenders and the Requisite Lenders shall
have executed and delivered to the Administrative Agent the Consent to the
Amendment.

            (b) The Second Supplemental Indenture (as defined therein) shall be
executed and delivered simultaneously with this Amendment in respect of the
corresponding provisions of the Existing Indenture, as amended (as defined in
the Second Supplemental Indenture).

            (c) The fee of 0.25% of the Total Revolving Credit Commitments shall
have been paid to the Administrative Agent for the account of those Lenders who
shall have delivered the Consent approving the Amendment to the Borrower prior
to the time the consent of the Requisite Aggregate Lenders and the consent of
the Requisite Lenders shall have been obtained, which fee shall be paid by the
Administrative Agent to each such Lender on a pro rata basis in proportion to
its Revolving Credit Commitment under the Credit Agreement.

            7. Representation and Warranties. To induce the Agents parties
hereto to enter into this Amendment, the Borrower and each other Loan Party
hereby represents and warrants to the Agents as of the Amendment Effective Date
that:

            (a) No Change. Since November 15, 1999, there has been no
development or event nor any prospective development or event, which has had or
could reasonably be expected to have a Material Adverse Effect.

            (b) Corporate Power; Authorization; Enforceable Obligations. Each
Loan Party has the corporate or other power and authority, and the legal right,
to make, deliver and perform this Amendment and has taken all necessary
corporate or other action to authorize the execution, delivery and performance
of this Amendment. No consent or authorization of, filing with, notice to or
other act by or in respect of, any Governmental Authority or any other Person is
required in connection with the execution, delivery, performance, validity or
enforceability of this Amendment, except for consents, authorizations, filings
and notices which have been obtained and are in full force and effect, and
except for other approvals the failure to obtain which could not reasonably be
expected to have a Material Adverse Effect. This Amendment has been duly
executed and delivered on behalf of each of the applicable Loan Parties. This
Amendment constitutes a legal, valid and binding obligation of each Loan Party
hereto enforceable against

<PAGE>   4
                                                                               4

such Person in accordance with its terms, except as enforceability may be
limited by applicable bankruptcy, insolvency, reorganization, moratorium or
similar laws affecting the enforcement of creditors' rights generally and by
general equitable principles (whether enforcement is sought by proceedings in
equity or at law).

            (c) No Legal Bar. The execution, delivery and performance of this
Amendment and the performance of the Loan Documents, as amended by this
Amendment, will not violate any Requirement of Law or any Contractual Obligation
of any Loan Party or Loan Parties or any of their Subsidiaries and will not
result in, or require, the creation or imposition of any Lien on any of their
respective properties or revenues pursuant to any Requirement of Law or any such
Contractual Obligation (other than the Liens created by the Security Documents).
No Requirement of Law or Contractual Obligation applicable to any Loan Party or
any of their respective Subsidiaries could reasonably be expected to have a
Material Adverse Effect.

            (d) Representations and Warranties in Credit Agreement. Each of the
representations and warranties made by the Loan Parties in Section 4 of the
Credit Agreement, as amended, or pursuant to the other Loan Documents are true
and correct in all material respects on and as of the Amendment Effective Date,
after giving effect to this Amendment, as if made on and as of the Amendment
Effective Date.

            8. Covenant. Each Loan Party hereby jointly and severally agrees
that the Mortgage and the Stock Pledge Trust Agreements shall be amended or
restated as necessary under Mexican law or as is deemed advisable by the Agents'
Mexican counsel in order to reflect this Amendment, which amendments shall be
effective no later than the date which is 60 days after the date hereof.

            9. General. (a) Payment of Expenses. The Borrower agrees to pay or
reimburse the Agents for all of their reasonable out-of-pocket costs and
expenses incurred in connection with this Amendment, any other documents
prepared in connection herewith and the consummation and administration of the
transactions contemplated hereby, including, without limitation, the reasonable
fees and disbursements of counsel to the Agents.

            (b) No Other Amendments; Confirmation. Except as expressly amended,
modified and supplemented hereby, the provisions of the Credit Agreement and the
Notes are and shall remain in full force and effect.

            (c) GOVERNING LAW. THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF
THE PARTIES HERETO SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN
ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

            (d) Counterparts. This Amendment may be executed by one or more of
the parties to this Amendment on any number of separate counterparts (including
by telecopy), and all of said counterparts taken together shall be deemed to
constitute one and the same instrument. A set of the copies of this Amendment
signed by all the parties shall be lodged with the Borrower and the
Administrative Agent.

<PAGE>   5
                                                                               5

       IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed and delivered by their respective proper and duly authorized
officers as of the day and year first above written.

                       FIRMAMENTO MEXICANO S. de R.L. de C.V.

                       By: /s/ Nicholas Moren
                           ---------------------------
                          Name: Nicholas Moren
                          Title: Authorized Signatory

                       By: /s/ Lauro Gonzalez
                           ---------------------------
                          Name: Lauro Gonzalez
                          Title:  Chief Executive Officer

                       SERVICIOS CORPORATIVOS SATELITALES S.A. de C.V.

                       By: /s/ Nicholas Moren
                           ---------------------------
                          Name: Nicholas Moren
                          Title: Authorized Signatory

                       By: /s/ Lauro Gonzalez
                           ---------------------------
                          Name: Lauro Gonzalez
                          Title: Authorized Signatory

                       SATELITES MEXICANOS, S.A. de C.V.

                       By: /s/ Nicholas Moren
                           ---------------------------
                          Name: Nicholas Moren
                          Title: Authorized Signatory

                       By: /s/ Lauro Gonzalez
                           ---------------------------
                          Name: Lauro Gonzalez
                          Title: Authorized Signatory

                       CITIBANK, N.A., as Administrative Agent

                       By: /s/ Mario Espinosa
                           ---------------------------
                          Name: Mario Espinosa
                          Title: VP<PAGE>   1
                                                                     EXHIBIT 4.8

                                                                  EXECUTION COPY

       ------------------------------------------------------------------

                       SATELITES MEXICANOS, S.A. DE C.V.,

                                 AS THE COMPANY,

                     FIRMAMENTO MEXICANO, S. DE R.L. DE C.V.
                                       AND
               SERVICIOS CORPORATIVOS SATELITALES, S.A. DE. C.V.,

                                  AS GUARANTORS

                                       AND

                                 CITIBANK, N.A.,

                                   AS TRUSTEE

                            ------------------------

                          SECOND SUPPLEMENTAL INDENTURE

                          Dated as of February 16, 2000

                            ------------------------

              Supplemental to Indenture, dated as of March 4, 1998
                       Original Issue of U.S.$325,000,000
                   Senior Secured Floating Rate Notes due 2004

    ------------------------------------------------------------------------

<PAGE>   2

            SECOND SUPPLEMENTAL INDENTURE, dated as of February 16, 2000 (the
"Second Supplemental Indenture"), by and among SATELITES MEXICANOS, S.A. de
C.V., a corporation (sociedad anonima de capital variable) organized under the
laws of the United Mexican States (the "Company"), FIRMAMENTO MEXICANO, S. de
R.L. de C.V., a limited liability company (sociedad de responsabilidad limitada
de capital variable) organized under the laws of the United Mexican States
("Holdings"), SERVICIOS CORPORATIVOS SATELITALES, S.A. de C.V., a corporation
(sociedad anonima de capital variable) organized under the laws of the United
Mexican States ("Mezzanine HoldCo" and, together with Holdings, the
"Guarantors") and Citibank, N.A., a national banking association duly
incorporated and existing under the laws of the United States of America, as
trustee (the "Trustee").

                                    RECITALS

            WHEREAS, the Company and the Guarantors executed and delivered the
indenture dated as of March 4, 1998, as amended by the First Supplemental
Indenture dated as of June 30, 1998 (the "Existing Indenture"), to the Trustee
to provide for the original issuance of the Company's Securities in the
aggregate principal amount of up to U.S.$325,000,000, which shall be the maximum
aggregate principal amount of Securities outstanding at any time, except as
provided in Section 2.7 of the Original Indenture;

            WHEREAS, the Company desires to, and the Trustee has agreed to,
amend the Existing Indenture as hereinafter provided;

            WHEREAS, the entry into this Second Supplemental Indenture by the
parties hereto has in all respects been authorized by the requisite Holders
under the provisions of the Existing Indenture and the Collateral Trust
Agreement, and the Trustee has determined that this Second Supplemental
Indenture is in form satisfactory to it; and

            WHEREAS, all acts and proceedings required by law, by the Existing
Indenture and by the organizational documents and By-Laws of the Company and the
Guarantors necessary to constitute this Second Supplemental Indenture a valid
and binding agreement of the Company, the Guarantors and the Trustee, in
accordance with its terms, and a valid amendment of, and supplement to, the
Existing Indenture, have been done and taken;

            NOW THEREFORE, in consideration of the premises and the purchases of
the Securities by the Holders thereof, the Company, the Guarantors and the
Trustee agree that the Existing Indenture is supplemented and amended, to the
extent and for the purposes expressed herein, as follows:

            1. Definition of Terms. For all purposes of this Second Supplemental
Indenture, except as otherwise herein expressly provided or unless the context
otherwise requires:

            (a) terms used herein in capitalized form and defined in the
     Existing Indenture shall have the meanings specified in the Existing
     Indenture

<PAGE>   3
                                                                               2

            (b) the words "herein", "hereof" and "hereunder" and other words of
     similar import used in this Second Supplemental Indenture refer to this
     Second Supplemental Indenture as a whole and not to any particular Article,
     Section or other subdivision;

            (c) the term defined in the first paragraph of the Recitals herein
     shall have the meaning specified therein;

            (d) the terms defined in this paragraph 1 have the meanings assigned
     to them in this paragraph 1 and include the plural as well as the singular.

            (e) the term "Second Supplemental Indenture" shall mean this
     instrument as originally executed or, if amended or supplemented pursuant
     to the applicable provisions of the Existing Indenture.

            2. Amendment to Section 4.16(a) of the Existing Indenture. Section
4.16(a) of the Existing Indenture is hereby amended by amending and restating in
its entirety the grid for the Consolidated Leverage Ration contained in such
section to read as follows:

<TABLE>
<CAPTION>
                          Each Fiscal Quarter                                       Consolidated
                          Ending During Period                                      Leverage Ratio
                          --------------------                                      --------------
<S>                                                                                <C>
                        December 31, 1999 to September 30, 2000                     7.50:1.00
                        December 31, 2000 to June, 30 2001                          7.25:1.00
                        September 30, 2001 to December 31, 2001                     7.00:1.00
                        March 31, 2002 to June 30, 2002                             6.75:1.00
                        September 30, 2002 to December 31, 2002                     6.50:1.00
                        March 31, 2003                                              6.25:1.00
                        June 30, 2003                                               6.00:1.00
                        September 30, 2003 to December 31, 2003                     5.50:1.00
                        March 31, 2004 and thereafter                               5.00:1.00
</TABLE>

            3. Amendment to Section 4.16(b) of the Existing Indenture. Section
4.16(b) of the Existing Indenture is hereby amended by amending and restating in
its entirety the grid for the Consolidated Interest Coverage Ratio contained in
such section to read as follows:

<TABLE>
<CAPTION>
                          Each Fiscal Quarter                                       Consolidated Interest
                          Ending During Period                                      Coverage Ratio
                          --------------------                                      ---------------------
<S>                                                                                 <C>
                        December 31, 1999 to September 30, 2000                     1.20:1.00
                        December 31, 2000 to June 30, 2001                          1.25:1.00
                        September 30, 2001 to June 30, 2002                         1.35:1.00
                        September 30, 2002 to December 31, 2002                     1.45:1.00
                        March 31, 2003                                              1.50:1.00
                        June 30, 2003                                               1.60:1.00
                        September 30, 2003                                          1.70:1.00
                        December 31, 2003                                           1.80:1.00
                        March 31, 2004                                              1.90:1.00
</TABLE>

<PAGE>   4
                                                                               3

<TABLE>
<S>                                                                              <C>
                        June 30, 2004                                               2.00:1.00
                        September 30, 2004 and thereafter                           2.25:1.00
</TABLE>

            4. Amendment to Section 4.8 of the Existing Indenture. The sixth
sentence of Section 4.8 of the Existing Indenture is hereby amended by deleting
the sentence in its entirety and replacing it by two new sentences to read as
follows:

      "If a loss of an insured satellite occurs, the Company shall deposit with
      the Collateral Trustee a portion of the insurance proceeds from such loss,
      as cash collateral for the Secured Facilities. The amount of such cash
      collateral shall be at least $25,000,000 and shall be held in the
      Insurance Proceeds Debt Service Sub-Account (as defined in the Collateral
      Trust Agreement), subject to release to pay debt service to the extent
      requested by the Company in amounts not to exceed, in any period, the
      amount of revenue lost during such period by reason of the loss of such
      satellite (as such revenue loss is reasonably estimated by the Company and
      certified by the Company in writing)."

            5. Amendment of Annex A to the Existing Indenture. Annex A to the
Existing Indenture is hereby amended by deleting the existing pricing grid in
its entirety and replacing it by a new pricing grid to read as follows:

<TABLE>
<CAPTION>
                        Consolidated            Applicable Margin-           Applicable Margin-
                        Leverage Ratio          Eurodollar Base Rate         Base Rate
                        --------------          --------------------         ------------------
<S>                                             <C>                          <C>
                        > 6.00 to 1.00                  4.50%                        3.50%
                        > 5.00 to 1.00                  4.00%                        3.00%
                        > 4.00 to 1.00                  3.25%                        2.25%
                        [ ] 4.00 to 1.00                3.25%                        2.25%
</TABLE>

            6. Miscellaneous.

            (a) Incorporation of Existing Indenture. All the provisions of this
Second Supplemental Indenture shall be deemed to be incorporated in, and made a
part of, the Existing Indenture; and the Existing Indenture, as supplemented and
amended by this Second Supplemental Indenture, shall be read, taken and
construed as one and the same instrument.

            (b) Representations, Warranties, Covenants and Agreements of the
Company and the Guarantors. (i) The Company and the Guarantors make and reaffirm
as of the date of the execution of this Second Supplemental Indenture all of
their respective representations, warranties, covenants and agreements set forth
in the Existing Indenture.

            (ii) The Guarantors consent to this Second Supplemental Indenture
and confirm that their respective guarantees remain in full force and effect
with respect to the Existing Indenture as supplemented hereby.

            (iii) The Company and the Guarantors jointly and severally agree
that, no later than the date which is 60 days after the date hereof, the
Mortgage and the Stock Pledge Trust

<PAGE>   5
                                                                               4

Agreements shall be amended or restated as necessary under Mexican law or as is
deemed advisable by the Company's Mexican counsel in order to reflect this
Second Supplemental Indenture. The Trustee is hereby authorized and directed to
execute such amendments and cause the same to be filed or recorded in accordance
with the advice of the Company's Mexican counsel.

            (c) Trustee Not Responsible for Recitals. The recitals contained
herein shall be taken as the statements of the Company, and the Trustee assumes
no responsibility for their correctness, except for the recital indicating the
Trustee's approval of the form of this Second Supplemental Indenture. The
Trustee makes no representation as to the validity or sufficiency of this Second
Supplemental Indenture.

            (d) Headings. The headings of the paragraphs and subparagraphs of
this Second Supplemental Indenture are inserted for convenience of reference and
shall not be deemed to be a part thereof.

            (e) Counterparts. This Second Supplemental Indenture may be executed
in any number of counterparts, each of which so executed shall be deemed to be
an original, but all such counterparts shall together constitute but one and the
same instrument.

            (f) Successors. All covenants and agreements in this Second
Supplemental Indenture by the Company and the Trustee shall bind their
respective successors. All covenants and agreements of the Trustee in this
Second Supplemental Indenture shall bind its successor.

            (g) Separability Clause. In case any provision in this Second
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

            (h) Benefits of Second Supplemental Indenture. Nothing in this
Second Supplemental Indenture, express or implied, shall give to any person,
other than the parties hereto and their successors hereunder and the Holders,
any benefit or any legal or equitable right, remedy or claim under this Second
Supplemental Indenture.

            (i) GOVERNING LAW. THIS SECOND SUPPLEMENTAL INDENTURE SHALL BE
GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW
YORK.

<PAGE>   6
                                                                               5

            IN WITNESS WHEREOF, the parties hereto have caused this Second
Supplemental Indenture to be duly executed as of February 16, 2000.

                          SATELITES MEXICANOS, S.A. de C.V.

                          By: /s/ N. Moren
                             ---------------------------------
                            Name: Nicholas Moren
                            Title:  Authorized Signatory

                          By: /s/ Lauro Gonzalez
                             ---------------------------------
                            Name: Lauro Gonzalez
                            Title: Authorized Signatory

                          FIRMAMENTO MEXICANO S. de R.L. de C.V.

                          By: /s/ N. Moren
                             ---------------------------------
                             Name: Nicholas Moren
                             Title: Authorized Signatory

                          By: /s/ Lauro Gonzalez
                             ---------------------------------
                             Name: Lauro Gonzalez
                             Title: Authorized Signatory

                          SERVICIOS CORPORATIVOS SATELITALES
                          S.A. de C.V.

                          By: /s/ N. Moren
                             ---------------------------------
                             Name: Nicholas Moren
                             Title: Authorized Signatory

                          By: /s/ Lauro Gonzalez
                             ---------------------------------
                             Name: Lauro Gonzalez
                             Title: Authorized Signatory

                          CITIBANK, N.A., as Trustee

                          By: /s/ Cindy Tsang
                             ---------------------------------
                             Name: Cindy Tsang
                             Title: V.P.

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