GPM Event Timeline
The timeline below highlights important dates for GPM including
recent events and those planned for the future up until the planned
launch of our Core Spacecraft. Events include mission reviews, spacecraft/flight
reviews, ground command and control segment reviews, planning workshops,
and the launch.
(If you would like a larger, printable version of the timeline,
click here (PDF).
More details are available on some of the most recent or upcoming
events - click on these items for the corresponding article.)
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GPM Holds Core Spacecraft Concept Review
A Spacecraft
Concept Review (SCR) is one of numerous reviews that are completed
during the lifecycle of a spacecraft. As a project proceeds from
initial concept formulation, to spacecraft design, development,
test, and finally to implementation, independent reviews provide
those responsible for building the spacecraft with ample opportunities
to ensure that the project is progressing according to plan, and
that project objectives will be fully achieved.
Convened after
the spacecraft requirements are established, an SCR allows project
personnel to identify risks inherent in the spacecraft design at
a fairly early stage in the design process. The spacecraft design
team can then mitigate the risks by incorporating appropriate design
changes, before the spacecraft has progressed into the detailed
design or development phases. The earlier the decision to change
the spacecraft design is made, the easier it is to incorporate the
changes. A successful SCR ensures that the spacecraft is designed
to best meet its purpose, and often results in significant time
and cost savings to the project.
GPM held its
Core SCR at Goddard Space Flight Center on 9-10 December 2002. During
the SCR, the Core Spacecraft team presented the design concept for
the GPM Core Spacecraft to a review team consisting of experts in
varying aspects of spacecraft design and operations. The review
team examined the design concept, bearing in mind the spacecraft
and mission requirements. Review team members discussed any risks
or concerns they had regarding the design, and documented them as
Requests For Action (RFAs). The RFAs were provided to the Core Spacecraft
Team after the review, along with a report summarizing the review
team’s findings.
Overall, the
SCR went well. In the summary report, the review team stated, “The
spacecraft team did an excellent job, presenting a thorough concept
which is approaching preliminary-design level in some areas.”
The review team commended GPM for employing reliability analysis
so early in the design phase, and observed that GPM’s application
of advanced computing technology—including use of a distributed
architecture—will likely result in cost savings. Also noted
were the benefits of the GPM Design for Demise, a plan to safely
dispose of the GPM Core Spacecraft at the end of its lifetime. Future
spacecraft programs will benefit from numerous features incorporated
in GPM’s Design for Demise, including decreased on-board propellant
requirements and reduced end-of -life operations cost. (For more
on the GPM Design for Demise, click here to view an article from
the June 2002 GPM Monitor.) In addition, the development of the
GPM Core Spacecraft in-house is enabling Goddard engineers to foster
and promote their mission systems development skill set.
The review team’s
primary concern regarding the current Core Spacecraft design is
that the spacecraft components (as they are designed now) will consume
more power than the power system is capable of generating. Implementation
of some design changes and further refinement of power consumption
estimates may be necessary to solve this problem, which must be
eliminated before the design can proceed further. In addition, the
review team expressed concern regarding plans for solar inertial
safehold, undefined launch vehicle interface parameters (including
definition of launch mass), underutilization of the Power Supply
Electronics (PSE) processors, the unusual solar array configuration,
and undefined instrument interfaces. All of these risks are documented
in the RFAs the review team generated. The Core Spacecraft Team
is currently working to respond to the actions by mid February 2003.
In lieu of a follow-on SCR, the SCR review team has requested the
opportunity to review the revised GPM Core Spacecraft concept at
a future Project Status Review (PSR), before they declare the spacecraft
concept viable.
In a message
to the entire GPM team, Project Formulation Manager Jim Adams congratulated
the GPM Core Spacecraft Team, commending them for their hard work
and untiring efforts, and stating, “Again, let me say how
very pleased we all were with the progress the Core design team
has made since June.”
By Lena
Braatz/Booz Allen Hamilton
For additional
information, please contact Dave Everett (david.f.everett@nasa.gov).
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So... What Is Next for
GPM?
The GPM team
has been busy working for months to prepare for the GPM Core Spacecraft
Concept Review (SCR) held on 9-10 December 2003 (click
here to view an article about the SCR). The review was very
successful, and the SCR review team commended GPM on the thorough
presentation of a mature design concept. Now that that milestone
has been achieved, however, what is next for the GPM team? The following
is a synopsis of some of the activities the team is engaged in as
GPM progresses toward its next major milestone—the Preliminary
Design Review (PDR).
The GPM Core
Spacecraft Team has received the report summarizing the findings
of the SCR review team, including a complete listing of the Requests
For Action (RFAs) generated. GPM is currently working to address
all of the RFAs by the mid-February 2003 deadline. Especially of
note are the SCR review team’s concerns regarding the spacecraft
power consumption. With the current design, engineers estimate that
the spacecraft components will require more power than the spacecraft
power system can generate. Not surprisingly, the GPM team is working
to remedy this problem, revisiting the design decisions that led
to such a power-hungry spacecraft design.
GPM staff members
are also working to enter the GPM Level 3 requirements into the
System Level Automation Tool for Enterprises (SLATE). SLATE is a
database tool that enables users to easily track and correlate multiple
layers of project requirements. GPM’s Level 1 requirements
(requirements specified by NASA Headquarters) and Level 2 requirements
(mission level requirements) are already recorded in SLATE. The
Level 3 requirements are requirements at the element level. Once
these requirements are entered into SLATE, subsystem engineers will
be able to use the system to track and trace requirements, link
them to risks in the GPM risk database, and link the requirements
to specific pieces of the GPM system.
The GPM team
is gathering information to support a congressionally mandated cost
assessment to be performed by the GPM Independent Review Team (IRT).
The IRT will independently estimate the cost of GPM, and compare
it to the estimate that GSFC has prepared. Discrepancies between
the two estimates are considered to be risks to the project. Additionally,
the President’s budget for the next fiscal year is slated
for release in early February 2003; GPM is looking forward to this
announcement so that the detailed project schedule can be defined
for the coming year.
Recently, GPM
released a Request For Proposal (RFP) for performance of an instrument
concept and risk reduction study for the GPM Microwave Imager (GMI)
instrument. The objective of the study is to develop an instrument
concept that is compliant with the design and performance requirements
for GMI, and that can be fabricated and assembled with a low level
of cost, technical and schedule risk. Multiple study contracts will
be awarded in late February 2003.
Finally, GPM
personnel are working with the Korean government to examine the
possibility of using the existing proto-flight model of the Korea
Multi-Purpose Satellite (KOMPSAT-1) as the bus for the GPM Constellation
Spacecraft. In fact, GPM representatives traveled to Korea in February
to meet with staff members from the Korea Aerospace Research Institute
(KARI) to discuss this effort. During the first week of March 2003,
GSFC’s Integrated Mission Design Center (IMDC) will conduct
a study to determine the modifications that would have to be done
to the Korean spacecraft bus to enable it to be converted into a
bus that could be used for the GPM Constellation Spacecraft. NASA
has a Letter of Agreement in place with the Korean government stating
that the two countries agree to work together to determine the feasibility
of using the Korean bus by July 2003.
By Lena
Braatz/Booz Allen Hamilton
For additional
information, please contact Dave Everett (david.f.everett@nasa.gov).
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