Massachusetts Institute of Technology
Kavli Institute for Astrophysics and Space Research
(MKI)
TESS INSTRUMENT
Preliminary Hazard Analysis
Dwg. No. 37-11004.08
Revision 04
October 16, 2014
Document Revision Record
Rev.
01
02
Date
7/21/14
10/15/14
03
04
10/16/14
10/17/04
Description of Change
Initial release
Clarify hazards and incorporate DHU
and Simulator.
Incorporate lifting structure.
Incorporate Heater Element.
Approved By
PRELIMINARY HAZARD ANALYSIS
1 Introduction
This document presents the TESS Instrument Preliminary Hazard Analysis (PHA) per the TESS
Mission Assurance Requirements document (MAR), DID 3-3, and the TESS MAR Compliance
Matrix. It documents an evaluation of the mishap risk being assumed prior to the testing or
operation of the TESS Instrument. The PHA is an input to the Instrument Safety Analysis Report
(ISAR).
1.1 Applicable and Reference Documents
The following documents include related documents and TESS Project policies.
 Materials and Processes List, DID 12-4
 ISAR Handbook, NASA SCL-13-1209
 TESS Mission Assurance Requirements Document, EXP-TESS-QA-0001
 TESS MAR Compliance Matrix, Document 37-10001.01
 TESS Environmental Requirements Document, EXP-TESS-GSFC-RQMT-0002
 MIT Kavli Institute Quality Assurance Manual
2 TESS Instrument
2.1 Functional Description
The TESS Instrument consists of four Charge-Coupled Device (CCD) cameras mounted to a
camera plate that acts as the mechanical interface to the spacecraft bus through K-Mount
Struts. The plate serves as an optical bench and also allows for the attachment to the sunshade
frame. The CCD cameras pass data to the Data Handling Unit (DHU), which acts as the data
and electrical interface to the spacecraft bus. The basic Camera Accommodation Structure can
be seen in Figure 2-1.
Figure 2-1: Camera Accommodation Structure
Each of the four wide field of view CCD cameras is identical, with the exception of the individual
lens hoods. As seen in Figure 2.2, each camera has a carbon composite lens hood, a lens
assembly, and a detector assembly. The lens assembly consists of seven lens elements
mounted to the lens housing. The detector assembly consists of the CCD array and the focal
plane array (FPA) electronics. Trim heaters and survival heaters are used to avoid dropping
below the minimum passive temperature of the FPA electronics.
Figure 2-2: Camera Cross-Section
At a high level of operations, the spacecraft will point the instrument toward the sector of the sky
of interest. Each lens assembly will focus incident light onto the corresponding detector
assembly; the data will be initially processed by the FPA electronics. All image and control data
is passed to the DHU. The DHU pre-processes and stores the data until the appropriate time to
transmit the data to the ground. The data is passed to the bus for transmission via the
spacecraft Ka band transmitter. Additionally, the DHU distributes electrical power from the
spacecraft bus to the instrument.
3 TESS Instrument Simulator
3.1 Functional Description
The TESS Instrument Simulator is a specialized computer that will provide electrical signals
representative of the instrument’s data output. The simulator will be used for spacecraft
hardware and software development efforts; it will not be connected to flight hardware. The
simulator will be delivered to the spacecraft developer for use at their development facility.
4 TESS Instrument Structural Sling
4.1 Functional Description
The TESS Instrument Structural Sling is a load-spreading device that will be used at the
spacecraft integrator to position the completed instrument onto the spacecraft. Further material
and design details will be provided in the ISAR.
5 Hazards
5.1
The ISAR Handbook, NASA SCL-13-1209 lists 27 potential hazards. They were examined
in detail for applicability to the TESS Instrument’s Cameras and Camera Accommodation
Structure, Data Handling Unit, and the Instrument Simulator; collectively, these will be
referred to as the Instrument/Simulator.
5.2
Not Applicable Hazards: The following hazards are not relevant to the TESS
Instrument/Simulator. They are listed below as listed in the ISAR handbook. Justification
why these hazards will not be addressed in the ISAR is provided.
 Toxic Material Out-gassing or Human Exposure (ISAR-1); Toxic materials will not be
utilized by the Instrument/Simulator. This may be verified by a review of the Materials
and Processes List, DID 12-4.
 Broken Glass (ISAR-2); Broken glass is a crew ingestion hazard. TESS is unmanned.
 Excessive Ionizing Radiation (ISAR-3); The TESS Instrument/Simulator does not
incorporate any ionizing radioactive source. This may be verified by a review of the
Materials and Processes List, DID 12-4.
 EVA Contact Hazard (ISAR-4); TESS is unmanned with no EVA.
 IVA Touch Temperature (ISAR-5); TESS is unmanned with no IVA.
 IVA Crew Contact Hazards (ISAR-6); TESS is unmanned with no IVA.
 Crew Exposure to LASER Emissions (ISAR-8); The TESS Instrument/Simulator does
not employ any Laser Technology. TESS is unmanned.
 Electrical Shock from Physiological Test Equipment (ISAR-9); TESS does not provide
or utilize any crew member Physiological Test Equipment.
 Battery Leakage/Rupture (ISAR-10); The TESS Instrument/Simulator does not
incorporate any batteries. This may be verified by a review of the Materials and
Processes List, DID 12-4.
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Hazardous Fluids Leakage in the Payload Faring (ISAR-12); The TESS
Instrument/Simulator does not incorporate any fluids. This may be verified by a
review of the Materials and Processes List, DID 12-4.
Ignition of Flammable Atmospheres (ISAR-13); The TESS Instrument/Simulator does
not incorporate any flammable fluids, gasses, or materials. This may be verified by a
review of the Materials and Processes List, DID 12-4
Exposure of the Payload to Excessive levels of EMI Radiation (ISAR-16); TESS is not
exposed to excessive levels of EMI Radiation.
Rupture and/or Explosion of Pressure System (ISAR-17); The TESS
Instrument/Simulator does not employ any pressure systems.
Leakage/Rupture of Sealed Containers (ISAR-18); The TESS Instrument/Simulator
does not employ any sealed containers. The space between lenses is vented to
normalize pressure.
Failure of Rotating Equipment (ISAR-20); The TESS Instrument/Simulator does not
have any moving parts or rotating equipment. Space flight rotating dynamic stresses
will be addressed in the Structural Failure section.
Partial or Incomplete Deployment/Jettison (ISAR-21); TESS does not incorporate any
deployment or jettison systems.
Collision/Impact during planned deployment (ISAR-22); TESS does not incorporate
any deployment.
Premature/Inadvertent Device Operation (ISAR-23); The TESS Instrument detectors
are digital CCD Cameras. No hazardous device operation is possible.
Must work pyrotechnic/debris generation (ISAR-24); TESS does not employ any
pyrotechnics.
Collision Following Premature/Inadvertent Appendage Deployment or Payload
Release/Deployment (ISAR-25); The TESS Instrument/Simulator does not employ
any Appendage Deployment.
Premature/Inadvertent liquid engine or attitude control system operation (ISAR-26);
The TESS Instrument/Simulator does not move. The Spacecraft does all
maneuvering and attitude control.
Premature/Inadvertent Solid Rocket Motor Firing (ISAR-27); The Tess
Instrument/Simulator does not employ any Solid Rocket Motors.
5.3
Applicable Hazards: The following hazards are relevant to the Instrument/Simulator. They
are listed below as listed in the ISAR handbook. Details on how these hazards will be
addressed will be provided in the ISAR and in the associated Hazard Reports.
 Electrical Shock (ISAR-7); Incidental contact by humans with high voltages (AC/DC)
can lead to severe burns and possibly other physiological effects.
 Use of Flammable Materials (ISAR-11); Use of flammable materials leads to injury to
the crew, damage to orbiter and other payloads through, fire, smoke and/or heat.
 Electrical Power Distribution Circuitry Damage (ISAR-14); Damage to electrical power
distribution circuitry can lead to damage to Bus wiring, loss of safety critical circuitry,
loss of redundant power sources, and/or generation of toxic products.
 Radio Frequency Radiation Induces Hazardous Effects On Avionics or Circuitry
(ISAR-15); RF radiation induces hazardous effects on avionics or circuitry. This
hazard applies to all mission phases.
 Structural Failure (ISAR-19); During launch, handling, or transportation, structure fails
result in damage to the launch vehicle, spacecraft, or injury to personnel. The hazard
report will include all load-carrying elements made of metals/alloys relevant to the
Instrument/Simulator.
5.4
Additional Hazards: The following hazards are relevant to the Instrument/Simulator.
Details on how these hazards will be addressed will be provided in the ISAR and in the
associated Hazard Reports.
 Ground Handling Equipment & Transport
 Human Factors Interface
 Instrument Heater Devices