## 2 Materials and Methods
### Methods  
The maximum environmental temperature during the operation of a deep space exploration spacecraft is 130 \({}^{\circ}\)C. Considering a certain margin, we propose carrying out stability analysis according to the temperature condition of 150 \({}^{\circ}\)C. According to the relevant regulations of GJB1307A-2004 [18], the minimum temperature of decomposition, spontaneous combustion, and melting of explosives should be at least 30 \({}^{\circ}\)C higher than the predicted maximum use temperature, so the test temperature was set to 180 \({}^{\circ}\)C.  
In some cases, pyrotechnics are exposed to extreme thermal temperatures for 2 days, so the designed test days were at normal conditions (60 \({}^{\circ}\)C, 4 h), rated working days (2 days), and extended working days (5 days, 10 days).  
According to the relevant standards and theory for the stability analysis of pyrotechnics, the Mg/TeO\({}_{2}\) ignition composition and its components were stored at 180 \({}^{\circ}\)C for 2 days, 5 days, and 10 days. After that, apparent morphology, XRD, DSC, weight loss ratio, content analysis, and _P_-_t_ curve tests were carried out to evaluate the thermal stability of the ignition composition of Mg/TeO\({}_{2}\). The test methods are described as follows:  
Scanning electron microscopy (SEM) was used to scan and image the surface of the sample point by point with a focused electron beam. The samples were characterized by using S-4800 (Hitachi, Japan) at 15 kV with a point resolution of 1.0 nm.  
X-ray diffraction (XRD): when the X-ray is incident on the crystal, the direction and intensity of the diffraction rays in space distribution are closely related to the crystal structure. The sample was measured with a Bruker D8 Advance diffractometer using 40 kV and 40 mA at Cu-K\({}_{\alpha}\) monochromatized incident radiation.  
Differential scanning calorimetry (DSC) is a technique to measure the change of heat flow rate of a sample with respect to the reference material under the control of the temperature program.  
The samples were tested by DSC-Q10 (TA Instruments, USA) with the heating rate of 5 \({}^{\circ}\)C-min\({}^{-1}\) from 50 \({}^{\circ}\)C to 520 \({}^{\circ}\)C in a nitrogen atmosphere.  
Weight loss ratio: the weight changes of the samples before and after storage at 180 \({}^{\circ}\)C were determined with an electronic balance (Mettler Toledo MX5, Switzerland), with an accuracy of 0.001 mg. The weight of the sample is about 2-10 mg.  
Content analysis: during the test, a sample weight of 0.11-0.13 g and hydrochloric acid of 40 mL were used for the reaction. The content of active magnesium was determined according to the amount of hydrogen produced by the chemical reaction of magnesium and hydrochloric acid. Two parallel determination results are needed, and the difference should be less than 0.4%.  
The _P-t_ test system included a closed bomb, pressure sensor, power supply, signal acquisition, and processing equipment. The closed bomb's cavity was 10 mL, and the measurement range of the pressure sensor (Kistler 601A, Germany) was 0-25 MPa. Power supply: Agilent E3634A. Signal acquisition and processing equipment consisted of a signal conditioner (Dewetron DEWE-RACK-16) and a dynamic analyzer (Dewetron DEWE-5001-TR).  
Table 1 gives a summary of high-temperature storage conditions, test materials, and thermal stability analysis test items.