February 7

7 February 1984

Astronaut Bruce McCandless II is a few meters away from the cabin of the Earth-orbiting space shuttle Challenger in this iconic photo taken by astronaut Robert Gibson. Credit: NASA

On February 7, 1984, during the STS-41-B mission of the Space Shuttle Challenger, astronauts Bruce McCandless II (1937–2017) and Robert L. Stewart (b. 1942) performed the first untethered spacewalks, operating the Manned Maneuvering Unit (MMU). Bruce McCandless flew out to a maximum of about 99 meters from the orbiter.

   The first MMU EVA began on mission day 5 of STS-41-B. For the EVA Commander Vance D. Brand (b. 1931) provided intravehicular support during suit-up, monitored MMU speed and distance using Challenger's radar, and flew the orbiter, while Mission Specialist Ronald E. McNair (1950–1987) operated the Remote Manipulator System (RMS) mechanical arm. In addition to testing the MMU in flight, Bruce McCandless and Robert Stewart performed a dress rehearsal for the Solar Maximum Mission (Solar Max) satellite retrieval, scheduled for the next flight (STS-41-C). Both flight MMUs were carried in the forward part of Challenger's payload bay. To help relieve the thrashing and banging which occurred during airlock depressurization on STS-6, Bruce McCandless pointed his head toward the airlock floor while Robert Stewart pointed toward the ceiling. 

   As he began his first test flight in the MMU, McCandless said, “that may have been one small step for Neil, but it’s a heck of a big leap for me,” humorously echoing Apollo 11 astronaut Neil A. Armstrong’s first words after stepping onto the lunar surface. McCandless spent 90 minutes checking and donning the port MMU, then tested it in the payload bay by maneuvering precisely around equipment. He found that the backpack shuddered and shook when forward movement was initiated in attitude hold. McCandless then moved 45 m (150 ft) out from Challenger, returned to the payload bay, flew out to 96 m (315 ft) and returned, then moved out again to about 99 m (325 ft). MMU nitrogen propellant use was higher than in simulations. Brand noted that the MMU's tracking lights were inadequate for finding the astronaut if he strayed away during orbital night, so ordered McCandless to hurry back to the payload bay before Challenger passed into darkness. Meanwhile, Robert Stewart installed a Manipulator Foot Restraint (MFR) on the RMS, but had to postpone a test ride because the EVA was behind schedule. 

Bruce McCandless II during his untethered EVA. Credit: NASA

   When McCandless returned to the payload bay, Stewart attached between the MMU arms the Trunnion Pin Attachment Device (TPAD) to be used to snare Solar Max. McCandless practiced docking with a trunnion pin mounted next to a mockup of the Solar Max main electronics box in the payload bay. McCandless reported later that he was chilled when out away from the payload bay. Robert Stewart then flew the MMU 93 m (306 ft) from Challenger. Vance Brand noted that Stewart was traveling at 0.6 mps (2 fps) about 90 m (300 ft) from Challenger, so warned him to slow down. Stewart tested the MMU for 65 minutes. Meanwhile, Bruce McCandless became the first astronaut to ride the MFR at end of RMS. The arm proved more stable for EVA work than expected. The two astronauts ended the spacewalk after 5 hours 55 minutes.

A fixed camera on astronaut Bruce McCandless II's helmet recorded this rare scene of the Space Shuttle Challenger some 50 to 60 meters away during a history-making extravehicular activity (EVA), February 7, 1984.  Astronaut Robert L. Stewart, standing beneath the Remote Manipulator System (RMS) arm, later donned the same Manned Maneuvering Unit (MMU). Credit: NASA

   The Manned Maneuvering Unit was designed and built by Martin Marietta Corporation (now, Lockheed Martin). It is constructed primarily of aluminum. The MMU is powered by two batteries with 852 watts at full charge, and propelled by 24 gaseous nitrogen thrusters, providing 1.4 pounds of thrust (6.2 newtons), each. The astronaut controls the MMU with two hand controllers. It has six-axis motion and automatic attitude hold. Including a full supply of nitrogen, the MMU weighs approximately 338 pounds (153.3 kilograms). It is designed for a maximum of 6 hours of operation. The unit is 50.0 inches (127.0 centimeters) high, 33.3 inches (84.6 centimeters) wide and with control arms extended, has a maximum depth of 48.0 inches (121.9 centimeters).

Robert L. Stewart begins his first test flight of the Manned Maneuvering Unit. Credit: NASA

© 2026, Andrew Mirecki

7 February 1999

Artist's rendering of the Stardust spacecraft. Credit: Stardust

On February 7, 1999, Stardust sample-return mission was launched from the Cape Canaveral Air Force Station in Florida, aboard a Delta II 7426 launch vehicle. Its primary goal was to collect dust samples from the coma of comet 81P/Wild (Wild 2), during the encounter on January 2, 2004, as well as samples of cosmic dust, and return these to Earth for analysis. En route to Wild 2, the spacecraft also flew by the asteroid (5535) Annefrank. Its sample capsule returned to Earth on January 15, 2006. During the mission extension the probe flew by comet 9P/Tempel (Tempel 1) on February 15, 2011.

Stardust during launch aboard a Delta II launch vehicle. Credit: NASA

Full Description from NASA Space Science Data Coordinated Archive:

   The primary objective of the Discovery class Stardust mission is to fly by the comet P/Wild 2 and collect samples (at least 1000 analyzable particles of diameter >15 microns) of dust and volatiles from the coma of the comet. It will then return these samples to Earth for detailed study. The secondary objectives are to collect and return to Earth at least 100 interstellar particles of diameter >0.1 micron, to obtain 65 images of the Wild 2 nucleus at resolutions of at least 67 microradians/pixel as well as images of the Wild 2 coma, and to perform in situ compositional analysis of cometary particles within the coma. The tertiary objectives are to perform in situ compositional analysis of interstellar grains, interplanetary dust and other cosmic particles, to collect Wild 2 coma volatiles, to determine Wild 2 coma dust flux and size distribution, to measure integrated dust fluence, large particle momentum and opportunistic estimate of the upper limit of the comet's mass, and to obtain dust flux profiles through Wild 2's coma. On Earth the cometary samples, representing primitive substances from the formation of the solar system, will undergo detailed analyses of the elemental, isotopic, mineralogical, chemical, and biogenic properties. The samples of interstellar dust, material from outside our solar system, will be carefully examined on Earth in regards to composition and size and velocity distribution. Stardust also flew by and imaged asteroid 5535 Annefrank.

Spacecraft and Subsystems

The Stardust spacecraft consists of a box-shaped main bus 1.6 m long, 0.66 m wide and 0.66 m deep with a high gain dish antenna attached to one face of the bus. The total mass of the spacecraft including the return capsule and 85 kg of propellant is 385 kg. The bus is made of flat panels fabricated with thin sheets of graphite fibers in polycyanate resin covering a lightweight aluminum honeycomb core. Two long (4.8 m tip-to-tip) rectangular solar arrays are connected by struts extending to the opposite sides of the spacecraft extending along the long axis of the spacecraft with their surfaces in the same plane as this face, extending parallel to each other in their long directions. The short cone-shaped 0.8 m diameter, 0.5 m high, 46 kg sample reentry capsule is attached at its narrow end to the back face of the bus. A paddle shaped sample collection disc can be extended from the capsule during periods of sampling, and stored inside the capsule enclosed by a cover when not in use. The propulsion units are on the rear face of the craft. A Whipple dust shield on the front of the craft protects the main core bus and is equipped with dust flux monitors, vibro-acoustic sensors which will be able to detect particle impacts on the shield. Two smaller shields protect the solar arrays.

   The spacecraft is also equipped with an optical navigation camera, a dust flux monitor, and a dust spectrometer/particle impact analyzer. There are no scan platforms, all science instruments are body-mounted. Propulsion is provided by a monopropellant hydrazine system. Attitude control is maintained by eight 4.4 N thrusters and eight 0.9 N thrusters, all mounted on the bottom of the spacecraft away from the sample collector to avoid contamination. Three axis attitude knowledge is given by a star camera and gyroscopic inertial measurement unit. Power is supplied to the craft by the silicon solar arrays which provide from 170 to 800 W depending on distance from the Sun. At the Wild-2 encounter about 330 W will be generated. Telecommunications are via X-band through a low gain antenna, medium gain horn, and 0.6 m diameter high gain dish. The system power is 15 W, the expected data rate at time of encounter is 7.9 kbits/sec using the 70 m Deep Space Network antennas on Earth.

Sample Collection

   Sample collection was achieved with the use of aerogel, a low-density (0.02 gm/cc) inert microporous silica-based substance which will allow capture of high-relative-speed particles with minimal physical and chemical alteration. The aerogel is in the form of a single disc-shaped sheet held by modular aluminum cells and deployed on a paddle. The aerogel is simply exposed to space during sample collection periods and stowed in the sample vault at other times. One side of the aerogel (the A side, 3 cm thick) will be used for collection of cometary samples and the other (B, 1 cm thick) side for interstellar dust. The appropriate side will be oriented toward the expected particle flux and particles striking the aerogel will be slowed down and trapped within. The number of particles should be small and the impacts will leave tracks in the aerogel. After all collections were completed, the aerogel was sealed in the sample vault of the sample reentry capsule, and the samples were recovered on Earth for study. The sample reentry capsule also contains an aeroshield/basecover, navigation recovery aids (GPS translator and emergency S-band beacon), an event sequencer, and a parachute system.

The nucleus of comet Wild 2. This image is the closest short exposure of the comet, taken at an 11.4-degree phase angle, the angle between the camera, comet and the Sun. Credit: NASA/JPL-Caltech

Mission Profile

   After a one day delay Stardust was launched on 7 February at 21:04:15.238 UTC. The launch took place from Pad A, Launch Complex 17 at Cape Canaveral Air Station aboard a Delta 7426 (a Delta II Lite launch vehicle with four strap-on solid-rocket boosters and a Star 37FM third stage). The four boosters fell away one minute and 6 seconds after liftoff (1:06 MET, mission elapsed time), the first stage shut down and was ejected at 4:30 MET. The second stage ignited a few seconds later, burned until 9:55 MET, followed by an ~11 minute coast and a reignition of the 2nd stage for 2 minutes. The 2nd stage separated at 24:27 MET and at 25:04 MET the 3rd stage ignited and burned for about 2 minutes. Stardust separated from the 3rd stage at 27:19 MET and opened its solar arrays 4 minutes later. The spacecraft is now coasting in an elliptical heliocentric orbit.

The first interstellar dust collection took place from 22 February to 1 May 2000. After one solar orbit, an Earth flyby on 15 January 2001 at 6008 km altitude was used to boost the spacecraft aphelion to 2.7 AU and the inclination to 3.6 degrees. Another period of interstellar dust collection opened July to December 2002. On 2 November 2002 at 04:50 UT Stardust flew within 3300 km of asteroid 5535 Annefrank. The relative velocity was 7 km/s. The dust collectors remained open throughout the flyby and images of the asteroid were taken. A second orbit of the sun was completed in mid-2003.

   The spacecraft entered the coma of comet P/Wild 2 on 31 December 2003. Close encounter took place on 2 January 2004. The fly-by had a closest approach within 250 km at roughly 19:45 UT at a relative velocity of about 6.1 km/s and took place 1.85 AU from the Sun and 2.6 AU from Earth. The sample collector was deployed on 24 December 2003 and was retracted, stowed, and sealed in the sample vault of the sample reentry capsule 6 hours after the fly-by. 72 images of the comet nucleus were also obtained, with predicted coverage of the entire sunlit side at a resolution of 30 m or better. The first (bumper) layer of the Whipple shield was breached by particle impacts at least ten times during the flyby.

   On 15 January 2006 the capsule separated from the main craft (with a stabilizing spin of 1.5 rpm) at 5:57 UT and entered the atmosphere four hours later at 9:57 UT. An aeroshell slowed the capsule down initially for about ten minutes, the drogue parachute was deployed at 10:00 UT and the main parachute 5 minutes later at an altitude of roughly 3 km. The capsule landed at 10:10 UT within a 30 x 84 km landing ellipse at the U.S. Air Force Test and Training Range in the Utah desert. High winds caused the capsule to drift about 5 miles north of its entry ground track, but with the aid of a locator beacon the capsule was found at 10:54 UT and was later transported by helicopter to a clean room, arriving at about 13:00 UT. The main spacecraft was diverted so as not to reenter Earth's atmosphere and is now in orbit around the Sun. It was put into hibernation on 29 January with only its solar panels and receiver active to save it for possible future missions. The spacecraft flew by Earth again for a gravity assist on 14 January 2009.

Stardust capsule on the ground. Credit: NASA

New Exploration of Tempel 1 (NExT)

   Stardust was funded for an extended mission to fly by Comet Tempel 1 on 14 February 2011, the New Exploration of Tempel 1 (NExT) mission, the spacecraft itself is now generally referred to as Stardust/NExT. Tempel 1 was the target of the Deep Impact mission, which delivered an impactor into the surface of Tempel 1 on 4 July of 2005. Stardust revisited the comet to look for signs of modification of the crater and extend the mapping of Tempel 1. The spacecraft flew by Tempel 1 at a distance of 181 km on 15 February at 4:39 UT following an encounter targeting period that started 18 October 2010. The images returned showed the impact crater caused by the Deep Impact mission. Stardust/NExT underwent a decommissioning burn and was commanded into safe mode with its transmitter off on 25 March 2011 at 00:30 UT.

The nucleus of comet Tempel 1 seen by Stardust

© 2026, Andrew Mirecki