Skip to content

MARS Associates

For Retirees of LM, ULA, and Legacy Companies

  • Home
  • About
    • MARS Officers & Directors
    • Policy Documents
    • MARS Overview
  • Benefits
    • Dental Plans
    • Vision Plans
    • Hearing Aid Discounts
    • Pre-Medicare
    • Understanding Medicare
    • VIA Benefits
    • ULA Benefits Contacts
    • Local Discounts
    • LM Corporate Discounts
    • Tax Adjustments
    • Informational Sessions Presentations
    • What to do when your loved one dies
  • Events
    • Calendar
    • Full Year Calendar
    • Special Activities
      • Special Event Planning Steps
    • Event Photos
  • Membership
    • Membership Renewal
    • New Member Application
    • Member Contact
    • Volunteer
    • MARS Logo Store
  • Clubs
    • Bridge Club
    • MARS Car Club
    • Golf Club
    • Hiking Club
    • PACESETTERS Club
    • Photography Club
    • LM Clubs & Leagues
  • Communications
    • MARS STAR
      • Archive
    • In Memoriam
    • Website Team
  • History
    • On This Day
    • MARS Moments
    • Brief History of LM Denver
    • Martin Marietta Archives
  • Toggle search form

On this day – April 20

Posted on April 20, 2025March 26, 2025 By Barb Sande

The events on this day in history for our heritage companies are noted below.

The earliest event was in 1959, the latest event was in 2006

Two milestone events (5 to 65+ years ago)

Human Spaceflight:

1972 – LANDING: Apollo 16 lands on the moon (Orion Lunar Module – Young and Duke)

1994 – LANDING: STS-59 (Endeavour), Edwards AFB

2010 – LANDING: STS-110 (Discovery), KSC – MILESTONE: 15 years ago

Military and Classified Programs:

1967 – LAUNCH: MM PRIME 3, GD Atlas SLV-3, SLC3W, VAFB

Exploration and Interplanetary Programs:

NONE

Earth-Monitoring and Civil Weather Satellite programs:

1967 – LAUNCH: RCA ESSA-5, Thor Delta E, SLC2E, VAFB

2004 – LAUNCH: LM Gravity Probe-B, Delta 7920-10C, SLC2W, VAFB

Commercial Programs:

2006 – LAUNCH: LM Astra 1KR, LM Atlas V 411, LC41, CCAFS

Test, ICBM, FBM programs:

1959 – LAUNCH: Lockheed Polaris AX, LC25A, CCAFS 

1964 – LAUNCH (2): Lockheed Polaris A2, SSBN625, ETR 

1965 – Final GD Atlas F departs 551st Strategic Missile Squadron for storage, Lincoln AFB, Nebraska – MILESTONE: 60 years ago

1966 – LAUNCH MM Titan II, 395-B, VAFB – Final Titan II operational test

1976 – LAUNCH (2): Lockheed Poseidon C3, SSBN656, ETR

Other:

NONE

Today’s photos are from two missions.  First, there are photos from the Apollo 16 mission, which landed on the moon on this day in 1972.  Apollo 16 landed in the Descartes Highlands region of the moon after some delays because of an oscillation problem in the Command/Service module SPS engine.  Photo Credits: NASA. 

Second, there is a photo of the PRIME 3 vehicle, which launched successfully on this day in 1967 and is now on display at the National Museum of the US Air Force in Dayton, Ohio.  PRIME was a small lifting body precursor to the X-24A & B.  PRIME stands for Precision Reentry Including Manuevering (re)Entry. Photo Credit: Found on Wikipedia, no author identified, attributed to government agency (NMUSAF). 

Specifications of PRIME also known as the X-23A (from Wikipedia):

General characteristics

  • Length: 6 ft 8 in (2.03 m)
  • Wingspan: 3 ft 10 in (1.17 m)
  • Height: 2 ft 10 in (0.86 m)
  • Gross weight: 894 lb (406 kg)
  • Powerplant: Nitrogen gas reaction control thrusters 

Performance

  • Maximum speed: 14,388 kn (16,557 mph, 26,647 km/h)
  • Maximum speed: Mach 25
  • Hypersonic L/D Ratio: 1:1
April 20 – John Young salutes the flag on the moon, Apollo 16. Photo Credit: NASA.
April 20 – Apollo 16 EVA with the lunar rover. Photo Credit: NASA.
April 20 – PRIME lifting body (flown vehicle) on display at the US Air Force Museum. Photo Credit: National Museum of the US Air Force (from Wikipedia).
On This Day

Post navigation

Previous Post: On this day – April 19
Next Post: On this day – April 21

Related Posts

  • On this day – November 13 On This Day
  • On this day – January 16 On This Day
  • On this day – February 8 On This Day
  • On this day – February 21 On This Day
  • On this day – April 11 On This Day
  • On this day – September 16 On This Day

More Related Articles

On this day – December 13 On This Day
On this day – April 23 On This Day
On this day – November 26 On This Day
On this day – July 9 On This Day
On this day – February 19 On This Day
On this day – August 2 On This Day

About us

MARS Associates
PO Box 1128
Littleton, CO 80160-1128

Suggestion Box

Find us on Facebook

Copyright © 2025 MARS Associates