VANGUARD 1 Codename "Relic"


VANGUARD is a payload satellite owned by NRL (US) in LEO that was launched on Mon, 17 Mar 1958 UTC via a VANGUARD launch vehicle from the Air Force Eastern Test Range (AFETR). Payload-class satellites include a variety of spacecraft equipped with specific instruments for various scientific and technological missions. These include communications satellites like Starlink; space stations such as the ISS; scientific satellites like the Hubble; Earth observation satellites from companies like Planet Labs, Umbra, and HawkEye 360; GPS; miniature CubeSats for education and research; and military/defense satellites.

Vanguard 1 was the fourth artificial satellite successfully launched into Earth orbit, following the Soviet Union's Sputnik 1 and 2, and the United States' Explorer

Launched on March 17, 1958, as part of Project Vanguard by the U.S. Naval Research Laboratory (NRL), this small, spherical satellite was a landmark achievement in the early days of the Space Race. Despite its diminutive size, which led Soviet Premier Nikita Khrushchev to mockingly label it the "grapefruit satellite," Vanguard 1 was the first satellite to successfully utilize solar power. Although communications ceased in 1964, it remains the oldest human-made object still orbiting the Earth, serving as a silent testament to the dawn of the space age.


  • Launch Vehicle: Vanguard TV-4, a three-stage rocket developed as part of Project Vanguard. The contractor for the vehicle was the Glenn L. Martin Company.
  • Launch Site: The satellite was launched from Cape Canaveral Air Force Station, Launch Complex 18A.
  • Orbit Details: Vanguard 1 was placed into an elliptical Medium Earth Orbit (MEO).
  • Perigee Altitude: 654 km (406 mi)
  • Apogee Altitude: 3,969 km (2,466 mi)
  • Inclination: 34.25 degrees
  • Orbital Period: 134.27 minutes
  • Propulsion: The satellite itself contained no propulsion system. Its orbit was achieved via the delta-v provided by its three-stage launch vehicle.
  • Power: Vanguard 1 featured a pioneering dual-power system. A 10 mW transmitter was powered by a mercury battery, while a separate 5 mW transmitter was powered by six solar cells mounted on the satellite's body. This marked the first use of solar cells to power a satellite, demonstrating the feasibility of long-duration space missions.
  • Mass: 1.46 kg (3.2 lb).
  • Manufacturer: The satellite was designed and built by the United States Naval Research Laboratory (NRL).
  • Dimensions: The spacecraft is an aluminum sphere with a diameter of 152 mm (6.0 inches). Six short antennas protrude from its body, giving it an antenna span of 0.91 m (3.0 ft).
  • Payload and Key Technologies:
  • Radio Transmitters: It carried two transmitters. The battery-powered transmitter operated at 108 MHz, and the solar-powered transmitter operated at 108.03 MHz. These were used for tracking and to determine the total electron content between the satellite and ground stations.
  • Sensors: Two thermistors were included to measure the interior temperature, allowing engineers to monitor the effectiveness of the satellite's thermal protection.
  • Solar Cells: The inclusion of six solar cells was its most significant technological innovation, proving that solar energy was a viable power source for spacecraft.


The primary objectives of the Vanguard 1 mission were multifaceted and foundational for the U.S. space program:

  • Launch Vehicle Test: A key goal was to test the launch capabilities and performance of the three-stage Vanguard rocket.
  • Satellite Systems Evaluation: The mission was designed to study the effects of the space environment on a satellite and its systems, particularly the novel solar cell power supply and thermal protections.
  • Geodetic Measurements: By precisely tracking the satellite's orbit, scientists aimed to obtain geodetic data to refine models of the Earth's shape, size, and gravitational field.
  • Atmospheric Studies: Analysis of the long-term orbital path provided valuable data on atmospheric drag at high altitudes, especially during periods of high solar activity.
  • Unprecedented Longevity: While the battery-powered transmitter lasted for about 20 days, the solar-powered transmitter continued to send signals for over six years, with the last contact made in May 1964. The satellite itself is expected to remain in orbit for approximately 240 years from its launch date.
  • Discovery of Earth's Shape: The analysis of Vanguard 1's orbital perturbations provided the first evidence that the Earth is not a perfect sphere. The data revealed a slight north-south asymmetry, leading to the description of Earth as being "pear-shaped," with a stem at the North Pole.
  • Solar Pressure Effects: Vanguard 1 was the first spacecraft where the effects of solar radiation pressure on its orbit were observed and measured. This pressure, along with atmospheric drag, caused significant perturbations that reduced its initial orbital life expectancy from 2,000 years to the current estimate of 240 years.
  • Potential Retrieval Mission: As the oldest artificial satellite in orbit, Vanguard 1 is a unique historical artifact. In recent years, discussions have emerged among aerospace analysts about the possibility of retrieving it from orbit. Such a mission would allow for the study of its materials—including solar cells, batteries, and metals—to understand the long-term effects of micrometeoroid impacts and the harsh space environment over more than six decades.


Vanguard 1 represents a monumental achievement in the history of space exploration. Despite its small size and the initial setbacks of Project Vanguard, it accomplished all its scientific objectives and more. It was the first satellite to demonstrate the viability of solar power, a technology now fundamental to nearly all spacecraft. Its scientific contributions, particularly the discovery of Earth's asymmetrical shape, fundamentally changed our understanding of geodesy. As the oldest human-made object in orbit, Vanguard 1 is not just a derelict satellite but a durable pioneer that continues to provide a baseline for studying the long-term orbital environment, cementing its legacy as a small but profoundly significant player in space history.


  • Vanguard 1 - Wikipedia
  • Vanguard 1: The Oldest Orbiting Satellite May Finally Return to Earth - Orbital Today
  • Vanguard 1 - Astronautix
  • Vanguard 1: Pioneering the Way for Space Exploration | New Space Economy
  • Vanguard 1, Oldest Manmade Satellite, Turns 60 This Weekend - AmericaSpace
  • The World's Oldest Satellite: Vanguard 1 - Everything Everywhere
  • Track VANGUARD 1 (NORAD ID: 5) live with Satcat
  • Vanguard 1 - Simple English Wikipedia, the free encyclopedia


Identifier 5, 1958-002B


Orbit - Low Earth LEO

Country Flag of US US

Related business Flag of US United States Navy (US)

ManufacturerNRLMissionSpacecraftBus & MotorNRL 6", Unknown motorMass2 kg wet, 2 kg dryLaunch date (UTC)1958-03-17 (68 years ago)


Launch vehicle VANGUARD


Launch site - Air Force Eastern Test Range (AFETR)


Object type

Payload

Rocket body

Debris

Shape & HBR Unknown Radar Cross SectionSmall (<0.1 m²)


Latest TLE

Historical TLE

TLE from 20 hours ago


Epoch: 2025-09-30T15:08Z

TLE epoch observation values (Epoch: 2025-09-30T15:08:06.242Z)

Latitude-0.00002°Longitude158.75804°Altitude1,032.218 kmSpeed7.832 km/sTrue Right ascension02h 21m 36sTrue Declination0° 00' 00"Sunlit

Object was in full shadow at epoch


Local Sidereal Time 04:26:58 Azimuth Unknown Elevation Unknown Doppler factor Unknown

Orbital elements

Apogee altitude 3,825.682 km Perigee altitude 651.604 km Semi-major axis 8,616.78 km Eccentricity0.18418 Inclination 34.2481°RAAN35.4013°Arg. of periapsis 48.2231°True anomaly311.83742°Mean anomaly326.1765° Eccentric anomaly319.29428° Mean motion 2.71347 °/minOrbital period132.67 mins BSTAR0.000087637

Orbital period <> Altitude timeseries

No atmospheric density data available

Atmospheric mass density (NRLMSISE-00) timeseries

Apogee altitude timeseries


Other satellites on launch #2 in the year 1958 (1958-03-17 UTC)

VANGUARD DEB, 1576VANGUARD R/B, 16

View VANGUARD 1, 5 on NASA - NSSDCA Website

View VANGUARD 1, 5 on Heavens-Above

View VANGUARD 1, 5 on Keep Track

View VANGUARD 1, 5 on Celestrak

View VANGUARD 1, 5 on Gunter's Space Page

Satcat and Kayhan Space are not affiliated with NASA, Celestrak, Heavens-Above, Keep Track, or Gunter's Space Page.


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