This chapter introduces the natural environment of launch site, thermal environment during Payload operation, electromagnetic environment during launch preparation and LV flight, as well as thermal environments, mechanical environments (vibration, shock & noise) during LV flight.

LM-2C can be launched in the three launch sites, JSLC, XSLC & TSLC. The natural environmental data in these three sites concluded by long-term statistic research. The environmental data in JSLC are emphasized as listed below.

• Temperature statistic result for each month at JSLC.
  

• The relative humidity at launch site is 35~55%. The dry season is all over the year, the average annual rainfall is 44mm.

Payload will be checked, tested in Payload Processing Buildings (BS2 and BS3) and then transported to the launch pad for launch. The environment impacting Payload includes 3 phases: (1) Processing in BS2 and BS3; (2) Transportation from BS3 to launch pad; (3) preparation on launch tower.

The satellite will be tested and fueled in the BS2 and BS3 which are equipped with air conditioning system. The temperature, humidity and cleanness can be guaranteed in the whole process. Refer to chapter 7.

After finishing fairing encapsulation in BS3, the fairing/payload combination will be transported to launch pad. The environment for Payload during transportation can be assured by temperature-control measures (such as thermal blanket). The environmental parameters in fairing are as follows:

Temperature: 10° C~25° C

Relative humidity: 30%~60%

Cleanliness: 100,000 level

The fairing air-conditioning system, shown in Figure 6-1, will be started after the payload was mated to the launch vehicle. The typical air-conditioning parameters inside the fairing are as follows:

Temperature: 15° C~22° C

Relative Humidity: 30%~45%

Cleanliness: 100,000 level

Air Flow Rate: 23~91kg/min

The air-conditioning is shut off at L-45 minutes and would be recovered in 40 minutes if the launch aborted.

The SC battery cooling system can also be provided with the following typical parameters:

Temperature: 10° C~16° C

Relative Humidity: 30%~60%

Cleanliness: 100,000 level

Air Flow Rate: >1.36kg/min

Relative pressure: <35Kpa

Characteristics of on-board radio equipment are shown below:

The payload is shielded by the launch tower and fairing. The electromagnetic strength is reduced 12dB at 0.1~10GHz comparing to the outside environment.

The energy levels of launch vehicle electromagnetic radiation and susceptibility are measured at SC/LV separation plane. They are shown in Figure 6-2 to Figure 6-5.

Figure 6-2 Narrow Band Magnetic Emission from LM-2C

Figure 6-4 Broad Band Electric Field Radiation from LM-2C

To conduct the EMC analysis among Payload, LV and launch site, both Payload and LV sides should provide related information to each other. The information provided by CALT are indicated in the Figure 6-2 to 6-5 in this chapter, while the information provided by SC side are as follows:

1. Payload RF system configuration, characteristics, working period, antenna position and direction, etc.
2. Values and curves of the narrow-band electric field of intentional and parasitic radiation generated by Payload RF system at Payload/LV separation plane and values and curves of the electromagnetic susceptibility accepted by Payload.

CALT will perform the preliminary EMC analysis based on the information provided by SC side, and both sides will determine whether it is necessary to request further information according to the analysis result.

SC side and CALT will coordinate the RF working time phase during launch campaign and LV flight.

The molecule deposition on Payload surface is less than 2mg/m²/week. The total mass loss is less than 1%. The volatile of condensable material is less than 0.1%.

The mechanical environment for Payload is at Payload/LV interface. The pressure environment and thermal environment is just for typical fairing.

When the launch vehicle flies in the atmosphere, the fairing air-depressurization is provided by 12 vents (total venting area 350cm²) opened on the lower cylindrical section. The typical design range of fairing internal pressure is presented in Figure 6-6. The maximum depressurization rate inside fairing will not exceed 6.0 kPa/sec.

The radiation heat flux density and radiant rate from the inner surface of the fairing is shown in Figure 6-7.

The free molecular heating flux at fairing jettisoning shall be lower than 1135W/m². After fairing jettisoning, the thermal effects caused by the sun radiation, Earth infrared radiation and albedo will also be considered. The specific affects will be determined through the Payload/LV thermal coupling analysis by CALT.

The longitudinal static acceleration is caused by the LV engine thrust and aerodynamic foresees. The acceleration is usually given in longitudinal static over load. The maximum overload is 4.6g for first stage flight and 6.7g for second stage flight, which could be varied slightly to different payloads.

The lateral static acceleration is caused by the LV maneuver and aerodynamic foresees. The maximum overload will not exceed 0.4g during the whole flight, which also could be varied slightly to different payloads.

The LV suffers engine thrust, aerodynamic forces (including buffeting during transonic phase, wind aloft, etc.), various separation forces (such as stage-1/stage-2 separation, fairing jettisoning, SC/LV separation, etc.) during powered flight phase. It is also affected by disturbances caused by engine jet and transonic acoustic noise. According to the acting forces and LV responses, the dynamic environment can be divided into sinusoidal vibration, random vibration, shock and acoustic.

The sinusoidal vibration mainly occurs in the processes of engine ignition and shut-off, transonic flight and stage separations. The sinusoidal vibration (zero-peak value) at Payload/LV interface is shown below.

Direction	Frequency Range (Hz)	Amplitude or Acceleration
		Two-stage LM-2C	LM-2C/CTS
Longitudinal	5 – 10	2 mm	2.5mm
	10 – 100	0.8g	1.0 g
Lateral	5 – 10	1.5mm	1.75mm
	10-100	0.6g	0.7g

The Payload random vibration is mainly generated by noise and reaches the maximum at the lift-off and transonic flight periods.

The random vibration Power Spectral Density and the total Root-Mean-Square (RMS) values at Payload/LV separation plane in three directions are given in the table below.

Frequency Range (Hz)	Power Spectral Density	Total RMS Value
20 - 150	+3dB/octave.	6.94 g
150 - 800	0.04 g2/Hz
800 - 2000	-6 dB/octave.

The flight noise mainly includes the engine noise and aerodynamic noise. The maximum acoustic noise Payload suffers occurs at the moment of lift-off and during the transonic flight phase. The values in the table below are the maximum noise levels in fairing.

The maximum shock Payload suffers occurs at the Payload/LV separation. Different separation mechanism and preload forces will affect the separation shock significantly. The typical shock response spectrum at Payload/LV separation plane is shown bellow.

To avoid the Payload resonance with launch vehicle, the primary frequency of Payload structure should meet the following requirement (under the condition that the Payload is rigidly mounted on the LV separation plane.):

During LV flight, the Payload suffers four cases: the transonic phase or Maximum Dynamic Pressure phase, the first stage engines shut down, the first and second stage separation, and the second stage main engines shut down. Therefore, the following limit loads at SC/LV separation plane corresponding to different conditions in flight are recommended for Payload design consideration.

• Usage of the above table:

• The direction of the longitudinal loads is the same as the LV longitudinal axis.
• The lateral load means the load acting in any direction perpendicular to the longitudinal axis.
• Lateral and longitudinal loads occur simultaneously.
• "+" means compress in axial direction.
• The loads are acting on the separation plane.

The Payload manufacturer should provide the Payload mathematical model to CALT for Coupled Loads Analysis (CLA). CALT will predict the Payload maximum dynamic response by coupled load analysis. The detailed data exchange requirements and special technical specifications will be coordinated by SC side and LV side.。The Payload manufacturer should confirm that the Payload could survive from the predicted environment and has adequate safety margin.

The main Payload structure must pass static qualification tests without damage. The test level must be not lower than Payload design load required in Paragraph 6.4.2.

During tests, the Payload must be rigidly mounted on the shaker. The tables below specifies the vibration acceleration level (zero - peak) of Payload qualification and acceptance tests at Payload/LV interface. (See Figure 6-8a&b).

• Frequency tolerance is allowed to be ± 2%
• Amplitude tolerance is allowed to be ± 10%
• Acceleration notching is permitted after consultation with CALT and concurred by all parties. Anyway, the coupled load analysis results should be considered , and the safety margin should be enough (CALT requires that safety factor ³ 1.25).

(For LM-2C/CTS)

During tests, the Payload structure must be rigidly mounted onto the shaker. The table below specifies the Payload qualification and acceptance test levels at Payload/LV interface. (See Figure 6-9).

• Tolerances of ±3.0 dB for power spectral density and ±1.5 dB for total rms values are allowed.

• The random test can be replaced by acoustic test.
  

The acceptance and qualification test levels are given in the following table (also see Figure 6-10).

Test Duration:

R Acceptance test: 1.0 minute

R Qualification test: 2.0 minutes

The shock test level is specified in Paragraph 6.3.4.4. Such test shall be performed once for acceptance, and twice for qualification. A ±6.0dB tolerance in test specification is allowed. However, the test strength must be applied so that in the shock response spectral analysis over 1/6 octave on the test results, 30% of the response acceleration values at central frequencies shall be greater than or equal to the values of test level. (See Figure 6-11)

The shock test can also be performed through Payload/LV separation test by using of flight Payload, payload adapter, and separation system. Such test shall be performed once for acceptance, and twice for qualification.

Frequency Range (Hz)	Shock Response Spectrum (Q=10)
100~1500	9.0 dB/oct.
1500~6000	4000g