Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Satellite | Launch date (UTC) | Decay | Mass(kg) | Diameter(m) | NSSDC ID | Nation | Usage |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Echo 1 | 1960-08-12 09:36:00 | 1968-05-24 | 180 | 30.48 | 1960-009A | US | pcr, ado, spc, tri |
| Explorer 9 | 1961-02-16 13:12:00 | 1964-04-09 | 36 | 3.66 | 1961-004A | US | ado |
| Explorer 19 (AD-A) | 1963-12-19 18:43:00 | 1981-10-05 | 7.7 | 3.66 | 1963-053A | US | ado |
| Echo 2 | 1964-01-25 13:55:00 | 1969-06-07 | 256 | 41 | 1964-004A | US | pcr, tri |
| Explorer 24 (AD-B) | 1964-11-21 17:17:00 | 1968-10-18 | 8.6 | 3.6 | 1964-076A | US | ado |
| PAGEOS 1 | 1966-06-24 00:14:00 | 1975-07-12 | 56.7 | 30.48 | 1966-056A | US | tri |
| Explorer 39 (AD-C) | 1968-08-08 20:12:00 | 1981-06-22 | 9.4 | 3.6 | 1968-066A | US | ado |
| Mylar Balloon | 1971-08-07 00:11:00 | 1981-09-01 | 0.8 | 2.13 | 1971-067F | US | ado |
| Qi Qiu Weixing 1 | 1990-09-03 00:53:00 | 1991-03-11 | 4 | 3 | 1990-081B | PRC | ado |
| Qi Qiu Weixing 2 | 1990-09-03 00:53:00 | 1991-07-24 | 4 | 2.5 | 1990-081C | PRC | ado |
Question:
What was the decay for the sattelite that was 180 kg?
Answer:
1968-05-24