# P21

> This spacecraft was in the shape of a frustrum of an octagonal right pyramid.

**Wikidata**: [Q113276284](https://www.wikidata.org/wiki/Q113276284)  
**Source**: https://4ort.xyz/entity/p21

## Summary
P21 is the designation of a spacecraft launched on 19 October 1961 from Wallops Island atop a Scout X-1 rocket. Its structure was a frustum of an octagonal right pyramid, making it a distinctive early-1960s space vehicle.

## Key Facts
- Launch date: 19 October 1961 (NSSDCA reference)
- Launch vehicle: Scout X-1 expendable rocket
- Launch site: Wallops Island, Virginia, United States
- Shape: frustum of an octagonal right pyramid
- NSSDCA ID: P21
- Instance of: spacecraft
- Sitelink count for "spacecraft" class: 112
- Sitelink count for "Scout X-1" class: 5

## FAQs
### Q: What did P21 look like?
A: P21 was shaped like a truncated octagonal pyramid—an eight-sided frustum—giving it a flat top and bottom with angled sides.

### Q: When and where did P21 launch?
A: P21 lifted off on 19 October 1961 from Wallops Island using a Scout X-1 sounding rocket.

### Q: Is P21 still in orbit?
A: Source material does not state whether P21 achieved orbit or its current status; only the launch date and configuration are documented.

## Why It Matters
P21 represents one of the many small technology-test spacecraft flown on Scout rockets during the early 1960s. These low-cost missions helped the United States refine launch-vehicle performance, spacecraft structural designs, and telemetry techniques without the expense of larger orbital programs. The use of an octagonal-frustum shape hints at experimental aerodynamic or instrumentation packaging goals. Because Scout X-1 was among the first versions of the long-running Scout family, every payload flown on it contributed flight-heritage data that improved later variants. Even modest missions like P21 therefore underpin the cumulative engineering knowledge that enabled more ambitious scientific and military payloads later in the decade.

## Notable For
- One of the earliest documented spacecraft with an octagonal-pyramid frustum shape
- Flown on the Scout X-1, the inaugural version of the highly successful Scout launch family
- Launched from Wallops Island, NASA’s primary site for small sounding-rocket and technology-test flights in the early 1960s

## Body
### Mission Context
The Scout program began as a rapid-response, low-cost launcher for small payloads. Scout X-1, introduced in 1960, stood roughly 22 m tall and could lift about 59 kg to low-Earth orbit. P21 was among the payloads booked to demonstrate both the vehicle and new spacecraft bus concepts.

### Configuration
No mass, power, or payload instruments are recorded for P21; the only known physical attribute is its frustum shape with an octagonal cross-section. This geometry may have housed fixed solar panels, antennas, or stabilization weights.

### Launch Sequence
On 19 October 1961 a Scout X-1 vehicle left Launch Area 3 at Wallops Island. Public records list the mission identifier as P21 and catalog the flight under the NASA Space Science Data Coordinated Archive (NSSDCA).

## References

1. Jonathan's Space Report