| Event | SE |
|---|---|
| Narrative | Crossed Flags Postmark #1: Washington, DC — 1979-07-20 Stamp: Viking 1 Lander Scooping up Soil on Mars, 15 cents (Scott #1759) |
| Cachet Sponsor | GWMSC |
| Design | Pictorial |
| Scott # | 1759 |
| Stock # | G-79-006 |
| Postmark Type | Special |
| Location | Washington, DC |
| Owner | GWMSC |