Explorer-1 Prime

{{short description|Picosatellite built by the Space Science and Engineering Laboratory}}

{{correct title|reason=bracket|Explorer-1 [Prime]}}

{{Use American English|date=January 2014}}

{{Use dmy dates|date=July 2024}}

{{Infobox spaceflight

| name = Explorer-1 [Prime]

| image =

| image_caption =

| mission_type = Radiation research

| operator = Space Science and Engineering Laboratory (SSEL),
Montana State University - Bozeman

| website =

| mission_duration = Failed to orbit

| spacecraft_bus = 1U CubeSat

| manufacturer =

| launch_date = 4 March 2011, 10:06 UTC

| launch_rocket = Taurus-XL

| launch_site = Vandenberg LC-576E

| launch_contractor =

| orbit_epoch = Planned

| orbit_reference = Geocentric orbit

| orbit_regime = Low Earth orbit

| orbit_periapsis =

| orbit_apoapsis =

| orbit_inclination =

| orbit_period =

| apsis = gee

}}

Explorer-1 [Prime], also known as E1P and Electra,{{cite web |url=https://web.archive.org/web/20090224205736/http://atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2008/session6/2-Explorer1-Celena_Byers.pdf |title=Explorer-1 Prime: A Re-flight of the Explorer-1 Science Mission |last=Byers |first=Celena |publisher=Montana State University |access-date=29 July 2024}} was a CubeSat-class picosatellite built by the Space Science and Engineering Laboratory (SSEL){{cite web |url=https://web.archive.org/web/20100707113207/http://ssel.montana.edu/explorer-1_prime/ |title=Explorer-1 PRIME |last=Space Science and Engineering Laboratory (SSEL)|access-date=29 July 2024}} at Montana State University. It was launched aboard a Taurus-XL rocket from Vandenberg Air Force Base, California on 4 March 2011,{{cite web |url=http://msdb.gsfc.nasa.gov/launches.php |title=Launches |last=Schwartz |first=Patrick C. |work=Mission Set Database |publisher=NASA GSFC |access-date=29 July 2024 |archive-url=https://web.archive.org/web/20090320221234/http://msdb.gsfc.nasa.gov/launches.php |archive-date=2009-03-20}} {{PD-notice}} but failed to achieve orbit after the rocket malfunctioned.

As part of NASA's ELaNA{{cite web |url=http://www.nasa.gov/home/hqnews/2010/jan/HQ_10-023_CubeSats.html |title=NASA Cues Up University CubeSats for Glory Launch This Fall |last=Trinidad |first=Katherine |date=26 January 2010 |publisher=NASA |access-date=29 July 2024 |archive-date=2010-07-07 |archive-url=https://web.archive.org/web/20100707070852/http://www.nasa.gov/home/hqnews/2010/jan/HQ_10-023_CubeSats.html}} {{PD-notice}} program, E1P was to be launched along with NASA's Glory satellite,{{cite web |url=https://space.skyrocket.de/doc_sdat/glory.htm |title=Glory |first=Gunter D. |last=Krebs |publisher=Gunter's Space Page |date=14 January 2023 |access-date=29 July 2024}} the Kentucky Space KySat-1 and the University of Colorado Boulder Hermes CubeSats.{{cite web |url=http://ssel.montana.edu/explorer-1_prime/2008/09/we-get-pressrelease-1.html |title=We get press-release |last=Jacobs |first=Danny |date=26 September 2008 |publisher=Montana State University |access-date=30 July 2024 |archive-url=https://web.archive.org/web/20100405020916/http://ssel.montana.edu/explorer-1_prime/2008/09/we-get-pressrelease-1.html |archive-date=2010-04-05}}

E1P was a re-flight mission of Explorer 1, the first American satellite, using modern technology including a Geiger tube donated by James Van Allen. The name of the satellite was also adopted from Van Allen, who referred to the satellite as Explorer-1 Prime prior to his death in 2006.

It was originally intended to be launched in 2008 to commemorate the 50th anniversary of the launch of Explorer 1. If it had been successful, E1P would have been Montana's first successful launch of a satellite after the loss of SSEL's MEROPE{{cite web |url=https://www.eurekalert.org/news-releases/604553 |title=Crash of Russian rocket destroys Montana's first satellite |last=Hiscock |first=Bill |date=27 July 2006 |publisher=Montana State University |access-date=30 July 2024}} in 2006.

There was a spare, Explorer-1 Prime Unit 2,{{cite web |url=http://www.amsat.org/amsat-new/satellites/satInfo.php?satID=143 |title=AMSAT |access-date=30 July 2024}} that was launched with NPP.{{cite web |url=http://ssel.montana.edu/e1p/e1ps-first-day/ |title=E1P's First Day!!! | Explorer-1 Prime |access-date=2011-11-26 |url-status=dead |archive-url=https://web.archive.org/web/20111109014110/http://ssel.montana.edu/e1p/e1ps-first-day/ |archive-date=2011-11-09}}

The Michigan Exploration Laboratory (MXL) suspects that the M-Cubed CubeSat, a joint project run by MXL and JPL, became magnetically conjoined to Explorer-1 Prime Unit 2, a second CubeSat released at the same time, via strong onboard magnets used for passive attitude control (see: Magnetorquer), after deploying on October 28, 2011. This is the first non-destructive latching of two satellites.{{cite web |date=9 July 2014 |title=MCubed-2 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2013-072H |access-date=July 9, 2014 |publisher=National Space Flight Data Center}} {{PD-notice}}