Seven years ago this week, the NASA X-43A scramjet-powered flight research vehicle reached a record speed of over 4,600 mph (Mach 6.83). The test marked the first time in the annals of aviation that a flight-scale scramjet accelerated an aircraft in the hypersonic Mach number regime.
NASA initiated a technology demonstration program known as HYPER-X in 1996. The fundamental goal of the HYPER-X Program was to successfully demonstrate sustained supersonic combustion and thrust production of a flight-scale scramjet propulsion system at speeds up to Mach 10.
Also known as the HYPER-X Research Vehicle (HXRV), the X-43A aircraft was a scramjet test bed. The aircraft measured 12 feet in length, 5 feet in width, and weighed nearly 3,000 pounds. The X-43A was boosted to scramjet take-over speeds with a modified Orbital Sciences Pegasus rocket booster.
The combined HXRV-Pegasus stack was referred to as the HYPER-X Launch Vehicle (HXLV). Measuring approximately 50 feet in length, the HXLV weighed slightly more than 41,000 pounds. The HXLV was air-launched from a B-52 mothership. Together, the entire assemblage constituted a 3-stage vehicle.
The second flight of the HYPER-X program took place on Saturday, 27 March 2004. The flight originated from Edwards Air Force Base, California. Using Runway 04, NASA’s venerable B-52B (S/N 52-0008) started its take-off roll at approximately 20:40 UTC. The aircraft then headed for the Pacific Ocean launch point located just west of San Nicholas Island.
At 21:59:58 UTC, the HXLV fell away from the B-52B mothership. Following a 5 second free fall, rocket motor ignition occurred and the HXLV initiated a pull-up to start its climb and acceleration to the test window. It took the HXLV about 90 seconds to reach a speed of slightly over Mach 7.
Following rocket motor burnout and a brief coast period, the HXRV (X-43A) successfully separated from the Pegasus booster at 94,069feet and Mach 6.95. The HXRV scramjet was operative by Mach 6.83. Supersonic combustion and thrust production were successfully achieved. Total engine-on duration was approximately 11 seconds.
As the X-43A decelerated along its post-burn descent flight path, the aircraft performed a series of data gathering flight maneuvers. A vast quantity of high-quality aerodynamic and flight control system data were acquired for Mach numbers ranging from hypersonic to transonic. Finally, the X-43A impacted the Pacific Ocean at a point about 450 nautical miles due west of its launch location. Total flight time was approximately 15 minutes.
The HYPER-X Program made history that day in late March 2004. Supersonic combustion and thrust production of an airframe-integrated scramjet were achieved for the first time in flight; a goal that dated back to before the X-15 Program. Along the way, the X-43A established a speed record for airbreathing aircraft and earned a Guinness World Record for its efforts.
Fifty-three years ago this week, Explorer III became the third artificial satellite to be successfully orbited by the United States. Interestingly, this early trio of successful orbital missions had been achieved in a period of less than 60 days.
The early Explorer satellites (Explorer I, II and III) were designated as Explorer A spacecraft. Their primary mission was to study the Earth’s Magnetosphere. Each satellite measured about 81-inches in length and had a maximum diameter of 6.5-inches. On-orbit weight was close to 31 pounds.
Explorer satellite instrumentation was modest. The primary instruments carried included a cosmic ray detector and micrometeorite erosion gauges. Data were transmitted to Earth using a 60 milliwatt dipole antenna transmitter and a 10 milliwatt turnstile transmitter. Electrical power was provided by mercury chemical batteries that accounted for roughly 40 percent of the payload weight.
Explorer I was the first artificial satellite to achieve Earth orbit. The satellite was launched atop a Jupiter-C launch vehicle on Friday, 31 January 1958 from LC-26A at Cape Canaveral, Florida. The country’s first satellite quickly went to work and discovered what we know today as the Van Allen Radiation Belts.
Explorer II was to verify and expand upon the findings of Explorer I. However, the craft never achieved orbit after it was launched on Wednesday, 05 March 1958. The cause was attributed to a failure in the 4th stage of its Jupiter-C launch vehicle. While the outcome was disappointing, the Explorer Program quickly readied another Explorer satellite for flight.
Explorer III was launched from Cape Canaveral’s LC-5 on Wednesday, 26 March 1958 at 17:31 UTC. The Jupiter-C launch vehicle performed admirably and delivered Explorer III into a highly elliptical 1,511-nm x 100-nm orbit. However, all was not well in orbit. Telemetry data indicated that the pencil-like satellite was tumbling at a rate of about 1 cycle every 7 seconds.
Explorer III performed its intended mission in spite of the anomalous tumbling motion. Indeed, the craft corroborated the findings of Explorer I and helped verify the existence of the Van Allen Radiation belts. However, the unwanted tumbling increased Explorer III’s aerodynamic drag and significantly shortened its mission lifetime.
Explorer III’s orbit decayed to the point that it reentered the Earth’s atmosphere on Tuesday, 27 June 1958. During its 93 days in space, the spacecraft made approximately 1,160 trips around the Earth.
Forty-five years ago this week, the crew of Gemini VIII successfully regained control of their tumbling spacecraft following failure of an attitude control thruster. The incident marked the first life-threatening on-orbit emergency and resulting mission abort in the history of Amercian manned spaceflight.
Gemini VIII was the sixth manned mission of the Gemini Program. The primary mission objective was to rendezvous and dock with an orbiting Agena Target Vehicle (ATV). Successful accomplishment of this objective was seen as a vital step in the Nation’s quest for landing men on the Moon.
The Gemini VIII crew consisted of Command Pilot Neil A. Armstrong and Pilot USAF Major David R. Scott. Both were space rookies. To them would go both the honor of achieving the first successful docking in orbit as well as the challenge of dealing with the first life and death space emergency involving an American spacecraft.
Gemini VIII lifted-off from Cape Canaveral’s LC-19 at 16:41:02 UTC on Wednesday, 16 March 1966. The crew’s job was to chase, rendezvous and then physically dock with an Agena that had been launched 101 minutes earlier. The Agena successfully achieved orbit and waited for Gemini VIII in a 161-nm circular Earth orbit.
It took just under six (6) hours for Armstrong and Scott to catch-up and rendezvous with the Agena. The crew then kept station with the target vehicle for a period of about 36 minutes. Having assured themselves that all was well with the Agena, the world’s first successful docking was achieved at a Gemini mission elasped time of 6 hours and 33 minutes.
Once the reality of the historic docking sank in, a delayed cheer erupted from the NASA and contractor team at Mission Control in Houston, Texas. Despite the complex orbital mechanics and delicate timing involved, Armstrong and Scott had made it look easy. Unfortunately, things were about to change with chilling suddeness.
As the Gemini crew maneuvered the Gemini-Agena stack, their instruments indicated that they were in an uncommanded 30-degree roll. Using the Gemini’s Orbital Attiude and Maneuvering System (OAMS), Armstrong was able to arrest the rolling motion. However, once he let off the restoring thruster action, the combined vehicle began rolling again.
The crew’s next action was to turn off the Agena’s systems. The errant motion subsided. Several minutes elapsed with the control problem seemingly solved. Suddenly, the uncommanded motion of the still-docked pair started again. The crew noticed that the Gemini’s OAMS was down to 30% fuel. Could the problem be with the Gemini spacecraft and not the Agena?
The crew jettisoned the Agena. That didn’t help matters. The Gemini was now tumbling end over end at almost one revolution per second. The violent motion made it difficult for the astronauts to focus on the instrument panel. Worse yet, they were in danger of losing consciousness.
Left with no other alternative, Armstrong shut down his OAMS and activated the Reentry Control System reaction control system (RCS) in a desperate attempt to stop the dizzying tumble. The motion began to subside. Finally, Armstrong was able to bring the spacecraft under control.
That was the good news. The bad news for the crew of Gemini VIII was that the rest of the mission would now have to be aborted. Mission rules dictated that such would be the case if the RCS was activated on-orbit. There had to be enough fuel left for reentry and Gemini VIII had just enough to get back home safely.
Gemini VIII splashed-down in the Pacific Ocean 4,320 nm east of Okinawa. Mission elapsed time was 10 hours, 41 minutes and 26 seconds. Spacecraft and crew were safely recovered by the USS Leonard F. Mason.
In the aftermath of Gemini VIII, it was discovered that OAMS Thruster No. 8 had failed in the ON position. The probable cause was an electrical short. In addition, the design of the OAMS was such that even when a thruster was switched off, power could still flow to it. That design oversight was fixed so that subsequent Gemini missions would not be threatened by a reoccurence of the Gemini VIII anomaly.
Neil Armstrong and David Scott met their goliath in orbit and defeated the beast. Armstrong received a quality increase for his efforts on Gemini VIII while Scott was promoted to Lieutenant Colonel. Both men were awared the NASA Exceptional Service Medal.
More significantly, their deft handling of the Gemini VIII emergency elevated both Armstrong and Scott within the ranks of the astronaut corps. Indeed, each man would ultimately land on the Moon and serve as mission commander in doing so; Neil Armstrong on Apollo 11 and David Scott on Apollo 15.
Forty-nine years ago today, the United States successfully launched Orbiting Solar Observatory No. 1 (OSO-1) into Earth orbit. This robotic spacecraft provided the first detailed scientific examination of the Sun from space.
The 1960’s was a time of both rapid growth and spectacular achievements in space exploration. Indeed, weather satellites, communications satellites and surveillance satellites were new inventions. Robotic space probes were sent to orbit and land on the Moon. Other autonomous spacecraft visited the inner planets of the Solar System. Men orbited the Earth. Still others landed on and returned from the Moon.
Space probes were also employed to good effect in an effort to learn more about our Sun. NASA’s Orbiting Solar Observatory (OSO) Program was America’s first attempt to acquire detailed solar physics data using orbital spacecraft. A total of eight (8) OSO space probes were launched into Earth orbit between 1962 and 1975.
The fundamental objective of the OSO Program was to monitor and measure solar electromagnetic radiation levels over an 11-year sun spot cycle. The idea was to map the direction and intensity of Ultraviolet, X-Ray and Gamma radiation throughout the celestial sphere over the long solar cycle. Onboard scientific instrumentation included a solar spectrometer, scintillation detector, proton electron analyzer and various flux monitors
OSO satellites were relatively large and complex for their time. Spacecraft attitude had to be tightly controlled since onboard instrument systems needed to be continuously trained on the solar disk. The probe’s solar physics data could be transmitted to ground receiving stations in real-time or recorded on tape for later transmittal.
OSO-1 was the first solar observatory orbited by the United States. Launch from Cape Canaveral’s LC-17A took place on Wednesday, 07 March 1962 at 16:04:00 UTC. A Thor-Delta 301/D8 launch vehicle placed the 458-lb OSO-1 satellite into a near circular Earth orbit (291-nm x 275-nm). The orbital period of 94.7 minutes meant that OSO-1 orbited the Earth 15.2 times each day.
OSO-1 performed well until its second onboard tape recorder gave up the ghost. This anomaly occurred on Tuesday, 15 May 1962. The loss of its last functional data recorder meant that all subsequent measurements had to be transmitted in real-time.
OSO-1 would continue making and transmitting solar physics measurements until May of 1964. At that time, the spacecraft power supply died when its solar cells failed. Although dormant, OSO-1 would continue to orbit the Earth for another seventeen (17) years. The spacecraft reentered the Earth’s atmosphere on Thursday, 08 October 1981.
OSO-1 and all succeeding OSO satellites contributed significantly to progress in the realm of solar physics. The OSO Program laid the foundation for more sophisticated and detailed study of our Sun through the auspices of such solar probes as SOHO, Ulysses and Skylab. Indeed, NASA’s Solar Probe Plus probe, currently scheduled to fly within the Sun’s coronal region sometime in the 2015/2016 period, will continue the legacy begun long ago by OSO-1.
Fifty-five years ago this month, the USAF/North American X-10 experimental research vehicle hit a maximum speed of Mach 2.05 during its 19th test flight. The mark established a new speed record for turbojet-powered aircraft.
The precedent set by the Nazi V-1 and V-2 Vergeltungswaffen (Vengeance Weapons) in World War II motivated the United States to launch a post-war effort to develop a strategic range-capable missile capability. The earliest example in this regard was the USAF/North American Navaho (SM-64).
Known as Project MX-770, the Navaho was developmental effort to deliver a nuclear warhead at a range of 5,500 nm. The Navaho configuration consisted of a rocket-powered first stage and a winged second stage utilizing ramjet propulsion. The second stage was designed to cruise at Mach 2.75.
The X-10 was a testbed version of the Navaho second stage. The X-10 measured 66 feet in length, sported a wingspan of 28 feet and had a GTOW of 42,000 lbs. The sleek aircraft was powered by twin Westinghouse J40-WE-1 turbojets. These powerplants burned JP-4 and were each rated at 10,900 lbs of sea level thrust in full afterburner.
The X-10 was a double sonic-capable aircraft. It had an unrefueled range of 850 miles and a maximum altitude capability of 44,800 feet.
The X-10 vehicle flight surfaces included elevons for pitch and roll control and twin rudders for yaw control. Canard surfaces were employed for pitch trim. The aircraft was designed to take-off, maneuver and land under external control provided by either airborne or ground-based assets.
A total of thirteen (13) X-10 airframes were constructed by North American. Flight testing originated at the Air Force Flight Test Center (AFFTC), Edwards Air Force Base, California and later moved to the Air Force Missile Test Center (AFMTC) at Cape Canaveral in Florida.
There was a total of twenty-seven (27) X-10 flight tests. Fifthteen (15) flight tests took place at the AFFTC between October of 1953 and March of 1955. Twelve (12) flight tests were conducted at the AFMTC between August 1955 and November 1956.
X-10 airframe GM-52-1 achieved the highest speed of the type’s flight test series. On Wednesday, 29 February 1956, the aircraft recorded a peak Mach Number of 2.05 during the 19th flight test of the X-10 Program. At the time, this was a record for turbojet-powered aircraft. The mission originated from and recovered to the AFMTC.
While the X-10 Program produced a wealth of aerodynamic, structural, flight control and flight performance data, test vehicle attrition was extremely high. The lone X-10 to survive flight testing was airframe GM-19307. It is currently on display at the Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio.
Fifty-six years ago this week, North American test pilot George F. Smith became the first man to survive ejection from an aircraft in supersonic flight. Smith ejected from his F-100A Super Sabre at 777 MPH (Mach 1.05) as the crippled aircraft passed through 6,500 feet in a near-vertical dive.
On the morning of Saturday, 26 February 1955, North American Aviation (NAA) test pilot George F. Smith stopped by the company’s plant at Los Angeles International Airport to submit some test reports. Returning to his car, he was abruptly hailed by the company dispatcher. A brand-new F-100A Super Sabre needed to be test flown prior to its delivery to the Air Force. Would Mr. Smith mind doing the honors?
Replying in the affirmative, Smith quickly donned a company flight suit over his street clothes, got the rest of his flight gear and pre-flighted the F-100A Super Sabre (S/N 53-1659). After strapping into the big jet, Smith went through the normal sequence of aircraft flight control and system checks. While the control column did seem a bit stiff in pitch, Smith nonetheless made the determination that his steed was ready for flight.
Smith executed a full afterburner take-off to the west. The fleet Super Sabre eagerly took to the air. Accelerating and climbing, the aircraft was almost supersonic as it passed through 35,000 feet. Peaking out around 37,000 feet, Smith sensed a heaviness in the flight control column. Something wasn’t quite right. The jet was decidely nose heavy. Smith countered by pulling aft stick.
The Super Sabre did not respond at all to Smith’s control inputs. Instead, it continued an uncommanded dive. Shallow at first, the dive steepened even as the 215-lb pilot pulled back on the stick with all of his might. But all to no avail. The jet’s hydraulic system had failed. As the stricken aircraft now accelerated toward the ground, Smith rightly concluded that this was going to be a short ride.
George Smith knew that he had only one alternative now. Eject. However, he also knew that the chances were small that he could survive what was quickly shaping-up to be a quasi-supersonic ejection. Suddenly, over the radio, Smith heard another F-100A pilot flying in his vicinity yell: “Bail out, George! He proceeded to do so.
Smith jettisoned his canopy. The roar from the airstream around him was unlike anything he had ever heard. Almost paralyzed with fear, Smith reflexively hunkered-down in the cockpit. The exact wrong thing to do. His head needed to be positioned up against the seat’s headrest and his feet placed within retraining stirrups prior to ejection. But there was no time for any of this now. Smith pulled the ejection seat trigger.
George Smith’s last recollection of his nightmare ride was that the Mach Meter read 1.05; 777 mph at the ejection altitude of 6,500 feet above the Pacific Ocean. These flight conditions corresponded to a dynamic pressure of 1,240 pounds per square foot. As he was fired out of the cockpit and into the harsh airstream, Smith was subjected to a drag force of around 8,000 lbs producing on the order of 40-g’s of deceleration.
Mercifully, Smith did not recall what came next. The ferocious windblast stripped him of his helmet, oxygen mask, footwear, flight gloves, wrist watch and even his ring. Blood was forced into his head which became grotesquely swollen and his facial features unrecognizable. His eyelids fluttered and his eyes were tortuously mauled by the aerodynamic and inertial load of his ejection. Smith’s internal organs, most especially his liver, were severely damaged. His body was horribly bruised and beaten as it flailed end-over-over end uncontrollably.
Smith and his seat parted company as programmed followed by automatic deployment of his parachute. The opening forces were so high that a third of the parachute material was ripped away. Thankfully, the remaining portion held together and the unconscious Smith landed about 75 yards away from a fishing vessel positiond about a half-mile form shore. Providentially, the boat’s skipper was a former Navy rescue expert. Within a minute of hitting the water, Smith was rescued and brought onboard.
George Smith was hovering near death when he arrived at the hospital. In severe shock and with only a faint pulse, doctors quickly went to work. Smith awoke on his sixth day of hospitalization. He could hear, but he couldn’t see. His eyes had sustained multiple subconjunctival hemorrhages and the prevailing thought at the time was that he would never see again.
Happily, George Smith did recover almost fully from his supersonic ejection experience. He spent seven (7) months in the hospital and endured several operations. During that time, Smith’s weight dropped to 150 lbs. He was left with a permanently damaged liver to the extent that he could no longer drink alcohol. As for Smith’s vision, it returned to normal. However, his eyes were ever after somewhat glare-sensitive and slow to adapt to darkness.
Not only did George Smith return to good health, he also got back in the cockpit. First, he was cleared to fly low and slow prop-driven aircraft. Ultimately, he got back into jets, including the F-100A Super Sabre. Much was learned about how to markedly improve high speed ejection survivability in the aftermath of Smith’s supersonic nightmare. He in essence paid the price so that others would fare better in such circumstances as he endured.
George Smith was thirty-one (31) at the time of his F-100A mishap. He lived a happy and productive thirty-nine (39) more years after its occurrence. Smith passed from this earthly scene in 1994.
Fifty-years ago this week, the NASA SCOUT small launch vehicle successfully orbited the Explorer IX satellite. This achievement marked the first time that an all-solid propellant launch vehicle orbited an artificial satellite.
The concept for the Solid Controlled Orbital Utility Test (SCOUT) launch vehicle dates back to the late 1950’s. The National Advisory Committee For Aeronautics (NACA) saw a need to develop a simple, low-cost launch vehicle for boosting small science payloads into space. Propulsion units for each stage would be selected from the existing inventory of solid rocket motors.
In the same time period, the United States Air Force (USAF) was moving toward the development of a small launch vehicle (SLV) to support a variety of suborbital and orbital military missions. The junior service subsequently partnered with the recently established National Aeronautics and Space Administration (NASA) in March of 1959 to develop a “poor man’s rocket.”
The SCOUT SLV was a 4-stage, all-solid propellant launch vehicle that stood roughly 75-feet in height. The initial version of the vehicle was designed to put a 130-lb payload into a 115 nm circular Earth orbit. The payload capacity of later versions approached 500 lbs. A fifth stage could be added to provide greater velocity performance for missions involving reentry vehicle research, highly elliptical orbits and solar probes.
The original SCOUT propulsion stack consisted of an Algol 1st stage (105,000 lbs thrust), Castor 2nd stage (64,300 lbs thrust), Antares 3rd stage (13,500 lbs thrust) and an Altair 4th stage (3,000 lbs thrust). Many variants of the SCOUT were developed over the program’s life time as the demand increased for higher payload capability. These variants were primarily the result of rocket motor thrust-level upgrades.
A compelling aspect of the SCOUT SLV was the fact that its launch support infrastructure was less involved that the bigger liquid-fueled launch vehicles such as Atlas, Delta and Titan. SCOUT was launched from at least three (3) separate sites; Wallops Island, VA, Vandenberg AFB, CA and San Marco Island just off the coast of Kenya. The latter pair of launch locations supported polar and equatorial orbit missions, respectively.
SCOUT developmental test flights began in April of 1960. The first ten (10) test flights included four (4) orbital attempts. The only successful orbital mission was that flown on Thursday, 16 February 1961 with launch taking place from LA-3 at the Wallops Flight Facility (WFF). The Explorer IX payload was successfully placed into orbit where it was used to study the density and composition of the upper thermosphere and lower exosphere. This mission also marked the first time that a satellite had been orbited from WFF.
While NASA’s SCOUT SLV program lasted more than three (3) decades and was very successful, USAF’s experience with the vehicle was quite different. Under the code names Blue SCOUT and Blue SCOUT Junior, the service employed variants of the basic SCOUT SLV for military missions. Hardware reliability issues and inter-organizational disconnects with NASA led to the USAF SCOUT SLV program being ended in 1967.
The NASA SCOUT SLV was flown 116 times between 1960 and 1994. Of that total, the break-out between research and development (R&D) flights and operational missions was 21 and 95, respectively. Parenthetically, it must be noted that the variety of space payloads launched by SCOUT is a story in itself. (One that must be told another day.) Suffice it to say here that SCOUT was a workhorse launch vehicle for NASA and contributed mightily to the scientific exploration of both near and deep space.
Thirty-seven years ago this month, the Mariner 10 interplanetary space probe successfully conducted a flyby encounter with the planet Venus. The Venusian flyby served as a necessary prelude to a subsequent first-ever flyby of the planet Mercury.
The Mariner Program concentrated on the scientific exploration of the inner planets of the solar system. Namely, Mars, Venus and Mercury. A total of ten (10) Mariner missions were attempted; seven (7) of which were successful. These missions were flown between 1962 and 1974. As outlined below, the Mariner Program recorded a number of important spaceflight firsts.
Mariner spacecraft were the first to successfully conduct a flyby of Venus (Mariner 2), Mars (Mariner 4) and Mercury (Mariner 10). Additionally, the first close-up photos of Mars and Venus were taken by Mariner 4 and Mariner 10, respectively. Mariner 9 was the first spacecraft to orbit Mars. Finally, Mariner 10 was the first space probe to fly a gravity assist trajectory and perform a flyby of two (2) planets (Venus and Mercury) during a single mission.
Mariner spacecraft weighed between 450 and 950 lbs for flyby missions and 2,200 lbs for an orbital mission. Each carried a variety of mission-specific sensors including radiometers, spectrometers and television cameras. Atlas-Agena (Mariners 1 to 5) and Atlas-Centaur (Mariners 6 to 10) launch vehicles provided the energy required for Earth-escape.
Mariner 10 was the last mission of the Mariner Program. The primary objectives were to make measurements of the space, atmospheric and surface environments of Venus and Mercury. This dual-planet mission required the first-ever use of a gravity assist maneuver to get to Mercury. In particular, the gravity of Venus would be used to deflect the Mariner 10 trajectory such that it would be able to encounter Mercury.
Mariner 10 was launched from Cape Canaveral’s LC-36B at 05:45 UTC on Saturday, 03 November 1973. It took 94 days for Mariner 10 to arrive at Venus. As a bonus, the space probe trained its complement of sensors on the Comet Kohoutek along the way. On Tuesday, 05 February 1974, Mariner 10 passed within 3,100 nm of the Venusian surface at 17:01 UTC. The spacecraft then sailed on toward its future flyby encounters with Mercury.
Mariner 10 learned many things about Venus. Venus was found to have an atmospheric circulation pattern somewhat like that of Earth. Although its strength is very much less than that of Earth, Venus was found to have a magnetic field. The planet’s ionosphere also interacted with the solar wind to produce a huge bow shock flowfield in the exoatmospheric region surrounding the planet.
Between March of 1974 and March of 1975, Mariner 10 performed three (3) flybys of the planet Mercury. The closest approach to the planet’s surface was a mere 177 nm. Mercury’s surface was found to be very Moon-like in that it is heavily-cratered. Spacecraft measurements also confirmed that Mercury does not have an atmosphere. Further, Mercury was found to have a predominatly iron-laden core as well as a small magnetic field.
Following the last of the trio of flyby encounters with Mercury, Mariner 10 systems were put through a number of engineering tests. The mission was officially brought to an end on Monday, 24 March 1975 when the spacecraft attitude control system propellant supply went to zero. Today, the Mariner 10 hulk continues in an eternal orbit about the Sun.
Fifty-years ago today, NASA successfully conducted a critical flight test of the agency’s Mercury-Redstone vehicle which helped clear the way for the United States’ first manned suborbital spaceflight. Riding the Mercury spacecraft into space and back was a 44-month old chimpanzee by the name of HAM.
Project Mercury was America’s first manned spaceflight program. Simply put, Mercury helped us learn how to fly astronauts in space and return them safely to earth. A total of six (6) manned missions were flown between May of 1961 and May of 1963. The first two (2) flights were suborbital shots while the final four (4) flights were full orbital missions. All were successful.
The Mercury spacecraft weighed about 3,000 lbs, measured 9.5-ft in length and had a base diameter of 6.5-ft. Though diminutive, the vehicle contained all the systems required for manned spaceflight. Primary systems included guidance, navigation and control, environmental control, communications, launch abort, retro package, heatshield, and recovery.
Mercury spacecraft launch vehicles included the Redstone and Atlas missiles. Both were originally developed as weapon systems and therefore had to be man-rated for the Mercury application. Redstone, an Intermediate Range Ballistic Missile (IRBM), was the booster for Mercury suborbital flights. Atlas, an Intercontinental Ballistic Missile (ICBM), was used for orbital missions.
Early Mercury-Redstone (MR) flight tests did not go particularly well. The subject missions, MR-1 and MR-1A, were engineering test and development flight tests flown with the intent of man-rating both the coverted launch vehicle and new spacecraft.
MR-1 hardly flew at all in that its rocket motor shut down just after lift-off. After soaring to the lofty altitude of 4-inches, the vehicle miraculously settled back on the launch pad without toppling over and detonating its full load of propellants. MR-1A flew, but owing to higher-than-predicted acceleration, went much higher and farther than planned. Nonetheless, MR flight testing continued in earnest.
The objectives of MR-2 were to verify (1) that the fixes made to correct MR-1 and MR-1A deficiencies indeed worked and (2) proper operation of a bevy of untested systems as well. These systems included environmental control, attitude stabilization, retro-propulsion, voice communications, closed-loop abort sensing and landing shock attenuation. Moreover, MR-2 would carry a live biological payload (LBP).
A 44-month old male chimpanzee was selected as the LBP. He was named HAM in honor of the Holloman Aerospace Medical Center where the primate trained. HAM was taught to pull several levers in response to external stimuli. He received a banana pellet as a reward for responding properly and a mild electric shock as punishment for incorrect responses. HAM wore a light-weight flight suit and was enclosed within a special biopack during spaceflight.
On Tuesday, 31 January 1961, MR-2 lifted-off from Cape Canaveral’s LC-5 at 16:55 UTC. Within one minute of flight, it became obvious to Mission Control that the Redstone was again overaccelerating. Thus, HAM was going to see higher-than-planned loads at burnout and during reentry. Additionally, his trajectory would take him higher and farther downrange than planned. Nevertheless, HAM kept working at his lever-pulling tasks.
The Redstone burnout velocity was 5,867 mph rather than the expected 4,400 mph. This resulted in an apogee of 137 nm (100 nm planned) and a range of 367 nm (252 nm predicted). HAM endured 14.7 g’s during entry; well above the 12 g’s planned. Total flight duration was 16.5 minutes; several minutes longer than planned.
Chillingly, HAM’s Mercury spacecraft experienced a precipitous drop in cabin pressure from 5.5 psig to 1 psig just after burnout. High flight vibrations had caused the air inlet snorkel valve to open and dump cabin pressure. HAM was both unaware of and unaffected by this anomaly since he was busy pulling levers within the safety of his biopack.
HAM’s Mercury spacecraft splashed-down at 17:12 UTC about 52 nm from the nearest recovery ship. Within 30 minutes, a P2V search aircraft had spotted HAM’s spacecraft (now spaceboat) floating in an upright position. However, by the time rescue helicopters arrived, the Mercury spacecraft was found floating on its side and taking on sea water.
Apparently, a combination of impact damage to the spacecraft’s pressure bulkhead and the open air inlet snorkel valve resulted in HAM’s spacecraft taking on roughly 800 lbs of sea water. Further, heavy ocean wave action had really hammered HAM and the Mercury spacecraft. The latter having had its beryllium heatshield torn away and lost in the process.
Fortunately, one of the Navy rescue helicopters was able to retrieve the waterlogged spacecraft and deposit it safely on the deck of the USS Donner. In short order, HAM was extracted from the Mercury spacecraft. Despite the high stress of the day’s spaceflight and recovery, HAM looked pretty good. For his efforts, HAM received an apple and an orange-half.
While the MR-2 was judged to be a success, one more flight would eventually be flown to verify that the Redstone’s overacceleration problem was fixed. That flight, MR-BD (Mercury-Redstone Booster Development) took place on Friday, 24 March 1961. Forty-two (42) days later USN Commander Alan Bartlett Shepard, Jr. became America’s first astronaut.
MR-2 was HAM’s first and only spaceflight experience. He quietly lived the next 17 years as a resident of the National Zoo in Washington, DC. His last 2 years were spent living at a North Carolina zoo. On Monday, 19 January 1983, HAM passed away at the age of 26. HAM is interred at the New Mexico Museum of Space History in Alamogordo, NM.
Seven years ago this week, NASA’s Mars Exploration Rover (MER) Opportunity landed at Meridiani Planum on the surface of the planet Mars. Incredibly, the robotic rover continues to gather geological, atmospheric and astronomical data well beyond its design mission duration of ninety (90) Martian days.
Mars is the 4th planet out from the Sun. It has a diameter a little more than half that of Earth. The duration of a day on Mars is a little more than that on Earth. However, a Martian year is 88% longer than a terrestrial year. While nebulous in comparison to the Earth, Mars has an atmosphere. Atmospheric temperature ranges from -190F to +98F.
Mars has always been a source of curious speculation by we Earthlings. Does or did Mars ever have water? Does or did Mars ever have life in any form? The quest to answer these and related questions has resulted in significant exploration of the Martian space, atmosphere and surface by robotic space vehicles sent from the Earth.
In 1976, Viking 1 and Viking 2 became the first American spacecraft to land on the surface of Mars. In July of 1997, the Mars Pathfinder became the first successful United States robotic rover. While a spectacular accomplishment, that first rover’s exploration capabilities and science output were modest. Something more substantial was required to provide a quantum leap in our understanding of Mars.
That something was the Mars Exploration Rover (MER) of which there would be two (2) copies. MER-A (Spirit) and MER-B (Opportunity) would be targeted to opposite hemispheres where each rover would investigate Martian geology up-close and personal. Each was configured with a sophisticated suite of scientific equipment for doing so. Together, the rovers were destined to provide the most detailed investigation of Martian geology in history.
Each MER weighs 408 lbs and measures 7.5-feet in width, 4.9-feet in height and 5.2-feet in length. Six (6) independently-driven wheels provide for rover locomotion and hill-climbing. Vehicle systems are typical with provision made for power generation, storage and distribution, vehicle guidance, navigation and control, data management, communication, and thermal control.
MER-A (Spirit) was launched on Tuesday, 10 June 2003 from SLC-17A at Cape Canaveral. Following a nominal entry and descent, the rover landed near Gusev Crater at 04:35 Ground UTC on Sunday, January 4, 2004. MER-B (Opportunity) was launched on Monday, 07 July 2003 from SLC-17B at Cape Canaveral. MER-B safely landed near Meridiani Planum at 05:05 Ground UTC on Sunday, 25 January 2004.
Both MER vehicles have produced images of and obtained scientific data on a myriad of Martian geologic features as they have roamed the region around their respective landing sites. They have operated for several thousand days beyond their 90-day design mission. That stunning success is due in great measure to the talented and dedicated mission operations and science teams back here on Earth.
In truth, any attempt to accurately synopsize here the myriad discoveries and scientific contributions of Spirit and Opportunity does both a disservice. Thus, to better grasp and appreciate the true scope and character of their incredible achievements, the reader is hereby invited to visit the following URL: http://marsrovers.jpl.nasa.gov/mission/status.html
Spirit was last heard from officially on Monday, 22 March 2010 (2,210 Mars days on the surface). The senior rover had traveled 4.8 miles during its many exploratory surface roamings. It is suspected that the vehicle is hibernating due to seasonally-low solar power levels. The hope is that Spirit will revive from its cold winter slumber when spring arrives this March at Gusev Crater.
As for Opportunity, it continues to continue! As of this writing, the junior rover is conducting a site survey at Crater Rim. It has been on the surface for 2,489 Mars days and has traveled in excess of 16.5 miles. Where this marvelous story ends is not clear at present. However, we do not have to wait for the day when MER-B finally goes silent to realize what has long been apparent; our noble exploratory marvel has afforded us a rare Opportunity indeed.
