Enclosure_BB--_2_JPSS_RTO.pdf

PRELIMINARY- OMES-2 JPSS

Background

NOAA has delegated procurement authority to NASA Goddard Space Flight

Center (GSFC) for the JPSS flight and ground system development and management. The GSFC JPSS Program develops and manages program and mission level requirements, and has responsibility for ensuring proper requirements allocation and verification to lower level requirements. The

Program systems engineering is responsible for end-to-end JPSS mission systems engineering that covers both flight and ground elements. This includes, but is not limited to, establishing and maintaining interfaces between flight and ground elements, so that communications between flight and ground elements are seamless and the data distribution to end user is uninterrupted.

The Program plans to develop and fly the same spacecraft bus and instruments for JPSS-1 through JPSS-4. However, there might be some design and system configuration changes due to on-orbit failures or unavailability of key components such as parts obsolescence. The program expects and plans to review on-orbit flight system performances and anomalies, and will implement alternate and/or corrective actions to the missions yet to be launched. It is the responsibility of program systems engineering to make sure all of the corrective actions and mitigations are appropriately implemented. Therefore, the systems engineering contractors are required to have experience and knowledge with design, requirements and system development, I&T and operation of spaceflight systems including Earth observing instruments.

Task Description

The long-standing CERES instrument is being updated to accommodate more robust science measurements. The new instrument (hereinafter referred to as “CERES_PLUS”) will need to develop new s/c interface requirements, performance requirements, Con-Ops, etc. that will lead to successful mission PDR (requirements driven event).

The performance goals for CERES_PLUS instrument are as below (CERES performance goals are provided in parenthesis):

1. Reliability of at least Ps=0.85 at 7 years (on-orbit years) with selective redundancy. (CERES: no reliability goal specified) (Ps = Probability of Success)

2. Mass requirement now 80 kg (CERES 55kg)

3. Instrument average power 100W, instantaneous 170W, survival 60W

(CERES average power 50W, instantaneous 104W)

4. 1/1/1 (m) Volume (CERES 0.6/0.6/0.576 (m))

5. Instrument data rate is 300 kbps (CERES data rate is 30 kbps)

6. Pointing requirements, per axis, 3 sigma

a. Control 360 arcsec

b. Knowledge 80 aresec

c. Stability 40/6.6 sec

(CERES Level 2 requirement: known pointing of the CERES instrument boresight, referenced to the center of the effective field of view for any channel, shall be within 2.50 km (3 sigma) at nadir.

Pointing requirements ( platform & instrument ) is 3 sigma (from aqua.nasa.gov/ceres)

d. Control 720 arcsec

e. Knowledge 180 arcsec

f. Stability 79 arcsec/6.6 sec)

7. Thermal: completely passive (assume: no power from S/C) and isolated from spacecraft (CERES is thermally controlled by heaters and radiators)

Subtask Description

The contractor shall:

1. Develop draft Interface Requirement Document (IRD) between JPSS-

1 spacecraft and CERES_PLUS. NOTE: for the IRD definition format, use the outline as specified in NASA Systems Engineering

Handbook: NASA/SP-2007-6105 Rev1 (available in e-library).

Numerical values for line items such as mass, voltage, power, etc.

may be listed as a range, if more detailed design beyond the information requested in the CERES_PLUS performance goals is needed for a complete solution. For each requirement include rationale, source, verification method, phase, priority and ownership.

a. Identify required alterations and interfaces between spacecraft and CERES_PLUS that will minimize impact on spacecraft modifications

b. Prioritize a list of redundant component/subsystems and provide a trade space with regards to reliability numbers, cost, mass and power as each component/subsystem is eliminated.

Include rationale for the prioritization and driving factors of the changes in each variable.

c. Provide recommendation(s) on how much data processing to do on board versus in the ground system including rationale.

2. Develop credible milestones for monitoring progress of

CERES_PLUS instrument development, and identify cut-off date if instrument will not meet spacecraft I&T schedule

a. In the event that the new instrument cannot meet planned delivery date, identify all changes on spacecraft that will need to be implemented to minimize impacts on spacecraft’s I&T schedule (as derived by launch readiness date).

3. Develop/update Con-Ops that will be required for CERES_PLUS

4. Develop on-orbit activation plan highlighting verification of redundant systems/components of CERES_PLUS

5. Identify components or sub-systems that would require life test with rationale that would demonstrate the reliability of at least 0.85 for 7 years (on-orbit years)

6. Develop list and timeline of deliverables between spacecraft provider and the instrument provider, clearly describe purpose and benefits of these deliverables, and how they will be used.

Applicable Documents

MSS 470-00019: JPSS-1 Mission Systems Specification

If information is not available In this document, Make the relevant assumptions and provide a list of assumptions made, with explanations of how these assumptions were derived at.

Deliverables

Table 1 - Deliverables

Deliverable Due Date

1. Draft IRD at PDR

2. Updated requirements documents, as needed

3. Spacecraft changes plan, if instrument cannot meet launch date

4. Con-ops for CERES_PLUS

5. Activation plan with emphasis on required verification of redundancies

6. List of components for life test

7. List and timeline of deliverables

Assumptions

1. The JPSS-1 mission risk classification shall be Class B, as per NPR

8705.4 Risk Classification for NASA Payloads.

2. The JPSS-1 mission shall operate for the Mission Lifetime in a polar sun-synchronous orbit with the following characteristics:

Nominal Altitude: 824 km +/- 17 km

Ground Track Repeatability Accuracy: +/- 20 km at the equator

Ground Track Repeat Cycle: 16 days

Nominal Ascending Equator Crossing Time: 1330 (local time) +/- 10 min.