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:
| Name | Launched | Vehicle | Ceased operation | Notes |
| --- | --- | --- | --- | --- |
| Injun 1 | June 29, 1961 | Thor-Able | March 6, 1963 | Failed to separate from Solrad 3; still in orbit |
| Injun 2 | January 24, 1962 | Thor-Able | failed at launch | Upper stage produced insufficient thrust |
| Injun 3 | December 12, 1962 | Thor-Agena | August 25, 1968 | Orbit decay and re-entry on August 25, 1968 |
| Injun 4 | November 21, 1964 | Scout X-4 | December 1966 | still in orbit |
| Injun 5 | August 8, 1968 | Scout X-4 | June 1971 | still in orbit[ citation needed ] |
| Injun 6 | June 3, 1974 | Scout X-4 | April 28, 1978 | main article: Explorer 52 |
Question:
What are the notes regarding the scout x-4 vehicle which ceased operation in June 1971?
Answer:
still in orbit[ citation needed ]