Make use of RMAN and define your retention policy.
Backup tablespace trans_pkp using something like (for as long as you like to keep it)
BACKUP TABLESPACE TRANS_BKP KEEP FOREVER NOLOGS TAG 'FIRSTHALF2014;
Truncate table transition_bkp
Restore:
- Make use of TSPITR (Automatic Tablespace Point-in-Time Recovery)
- Utilize RMAN duplicate from backup and set until time
You might want to use a naming convention for the tablespace. Like TRANS_BKP_01_2014, TRANS_BKP_02_2014, etc...