Names | TO2-IM [1] CLPS-2 [2] |
---|---|
Mission type | Lunar landing |
Operator | Intuitive Machines |
COSPAR ID | 2024-030A |
SATCAT no. | 58963 |
Mission duration | 14 days [3] |
Spacecraft properties | |
Spacecraft | Odysseus |
Spacecraft type | Nova-C |
Manufacturer | Intuitive Machines |
Launch mass | 1,900 kg (4,200 lb) |
Start of mission | |
Launch date | February 15, 2024, 06:05:00 UTC |
Rocket | Falcon 9 Block 5 (B1060.18) ♺ |
Launch site | Kennedy, LC-39A |
End of mission | |
Declared | March 23, 2024[4] |
Last contact | February 29, 2024[3] |
Lunar lander | |
Landing date | February 22, 2024, 23:23:00 UTC |
Landing site | Malapert A 80°08′S1°26′E / 80.13°S 1.44°E [5] |
IM-1 mission insignia Motto: ADTIGO PLANITIA LUNAE (I touch the plains of the Moon) (Stick The Landing) [6] |
IM-1 was a robotic Moon landing mission conducted by Intuitive Machines (IM) in February 2024 using a Nova-C lunar lander. After contact with the lunar surface on February 22 the lander tipped to an unplanned 30 degree angle. All instrument payloads remained functional and the mission was deemed a success. [7] IM-1 was the first commercial mission to successfully soft-land on the Moon. [8] [9] NASA provided funding support for the mission through the Commercial Lunar Payload Services program. The lander, named Odysseus, carried six NASA-developed payloads and several others from commercial and educational customers. On February 29, Odysseus lost power and shut down with the start of the lunar night. [3]
IM-1 was the first soft lunar landing by a private company [10] [11] and Odysseus was the first American-made spacecraft to soft-land on the Moon since Apollo 17 in 1972. Steve Altemus, CEO of IM, says Nova-C is the first liquid methane and liquid oxygen (methalox)-powered spacecraft to fire beyond low-earth orbit, and also the first methalox spacecraft to land on an off-world celestial body. [12]
In December 2017, Space Policy Directive 1 signaled an intention to return astronauts to the Moon. [13] Excerpts from NASA documents obtained by The New York Times suggested the agency would prioritize the private spaceflight sector. [14] [15] In November 2018, NASA announced the Commercial Lunar Payload Services program, selecting nine companies to deploy payloads for the agency. [16] In May 2019, NASA announced that Astrobotic Technology, Intuitive Machines, and Orbit Beyond would develop lunar landers, awarding Intuitive Machines US$77 million. [17] Intuitive Machines was paid US$118 million to develop the Odysseus lunar lander used in the IM-1 mission.
The IM-1 mission in February 2024 followed the Peregrine mission by Astrobotic Technology, which launched in January 2024. [18] [19] The Peregrine landing at Gruithuisen Domes was abandoned when a propellant leak was observed after launch, and the spacecraft was guided to re-enter Earth's atmosphere. [20]
Odysseus was equipped with six instruments developed by NASA, including a laser retroreflector array, a lidar navigation device, a stereo camera, a low-frequency radio receiver, the Lunar Node-1 beacon, and an instrument to monitor propellant levels. Additionally, a camera built by students at Embry–Riddle Aeronautical University, Daytona Beach, a planned Moon telescope, and a Jeff Koons art project were also on board. [21] In total the payloads comprise six NASA scientific instruments and six commercial instruments (five of the latter being scientific and one cultural). [22]
Odysseus landed at the Malapert-A crater and stayed active there for about a week, before the Sun sets at the landing site. [23] The Odysseus lander is not designed to survive the lunar night, which lasts about two weeks. [24]
The lander has a chip with works of 200 artists, including works of Pablo Picasso, Michelangelo Buonarroti, Jeff Koons and Bram Reijnders. [25] [26] The lander carries the sculpture Moon Phases by Jeff Koons within its payload. This is the first sculpture installation to reach the Moon since Paul Van Hoeydonck's Fallen Astronaut sculpture was placed on the Moon by David Scott of Apollo 15 in 1971. [27] [28] Koons describes Moon Phases as, "125 miniature Moon sculptures, each approximately one inch in diameter." [29]
The lander also carries private disclosed and undisclosed payloads from commercial company's, educational institutions, and private citizens. One being the Lunaprise time capsule, which includes the Lunar Library compiled by the Arch Mission Foundation. [22] The Lunar Library includes content from the English Wikipedia and the Rosetta Project. [30] [31] Also included onboard is the AstroVault by Quantum Aerospace which includes an archive of musical recordings and photos, which features songs by Jimi Hendrix, Bob Marley, and Elvis Presley, among other musicians. [32] [33]
A Radio Frequency Mass Gauge (RFMG) on board estimated how much propellant was available during the IM-1 mission. This was the first long-duration test of an RFMG on a standalone spacecraft. [34] [35]
Name | Agency/Company | Type | Details |
---|---|---|---|
Nova-C Odysseus | Intuitive Machines | Lunar lander | The Landing Component of the mission. It will also provide support to the equipment. |
ILO-X [36] | International Lunar Observatory | Instrument | Proof of concept wide and narrow field imagers |
Laser Retro-Reflector Array [37] | NASA | Instrument | A passive optical instrument with eight laser retroreflectors that spacecraft could use for precision determination of their distance to the reflectors. The array provides a permanent location marker on the Moon. [35] |
Navigation Doppler Lidar for Precise Velocity and Range Sensing [37] | NASA | Instrument | Included as a technology demonstration payload, NDL was used operationally by Odysseus when the primary mission lidar was discovered to be inoperable. [38] |
Lunar Node 1 Navigation Demonstrator [37] | NASA | Instrument | A CubeSat-sized experiment to demonstrate autonomous navigation that could be used by landers, rovers, surface infrastructure and astronauts to confirm their relative positions on the Moon. [35] |
Stereo Cameras for Lunar Plume-Surface Studies [37] | NASA | Instrument | A suite of four cameras to capture imagery showing how the Moon's surface changes from interactions with the spacecraft's engine plume during and after descent. [35] |
Radiowave Observations at the Lunar Surface of the photoElectron Sheath (ROLSES) [39] | NASA / University of Colorado Boulder | Instrument | The instrument will observe the Moon's surface environment in radio frequencies, to determine how natural and human-generated activity near the surface interacts with and could interfere with science conducted there. [35] |
AstroVault [33] | Quantum Aerospace | Private Commercial Cargo | Confidential |
EagleCam [40] | Embry–Riddle Aeronautical University | CubeSat | A Cubesat that was planned to record the landing after ejecting from IM-1 about 30 m before touchdown. [35] |
Moon Phases art cube [29] | Pace Verso / 4Space / NFMoon | Sculpture | Passive payload blocked after lander tilted to the side hosting this payload, post landing. [41] |
Omni-Heat [22] | Columbia Sportswear | Space blanket | |
Independence [22] | Lonestar | Lunar data center test mission |
In December 2023, Odysseus arrived at Kennedy Space Center for processing. [42] On January 31, 2024, the Odysseus spacecraft was encapsulated in the payload fairing of its Falcon 9 Block 5 launch vehicle. [43] On February 13, IM announced that two wet dress rehearsals loading Odysseus with propellants had been successful and they were ready for launch. [44] [45]
A reusable Falcon 9 booster carrying Odysseus lifted off from LC-39A in Florida at 06:05 UTC on February 15, 2024. The booster returned to LZ-1 and the expended Falcon 9 upper stage delivered the spacecraft to its translunar trajectory.
Originally planned to launch on February 13, SpaceX postponed the launch after reporting a technical issue with propellant loaded onto the lander. [21] [46]
After separation from the launch vehicle, the Nova Control operations center established communication with the lander and conducted initial checkouts. Images captured by the spacecraft after separation from the launch vehicle were released on February 17. [47]
The lander was scheduled to perform a main engine "commissioning burn" on February 15. Trent Martin, Intuitive Machines vice president of Space Systems, described this as a "critical step" for the mission. [48] After reporting issues with the IM-1 star tracker and adjustment of the liquid oxygen line cooling time IM reported a successful commissioning burn on February 16. [49] [50] The maneuver resulted in a 21 m/s (47 mph) change in the lander's velocity. [51]
Intuitive Machines planned for up to three trajectory adjustment maneuvers during the trans-lunar phase of the mission. [49] The first was completed on February 18, [51] and after the second maneuver on February 20, there was no need for a third. [52]
On February 20, Intuitive Machines reported that Odysseus had completed approximately 72% of its journey to the Moon's surface. [53]
Odysseus performed its lunar orbit insertion (LOI) on February 21, altering its velocity by 800 m/s (1,800 mph). Intuitive Machines reported the 408-second main engine LOI burn placed the lander in a 92 km (57 mi) lunar orbit. [54] [55] On February 22 IM indicated a "lunar correction maneuver" had raised the orbit. [56]
The lander spent approximately 24 hours orbiting the Moon before its descent to the lunar surface on February 22. [57] [58] [55] On February 21, while still in orbit, Odysseus sent back high-resolution images of the lunar surface.
Intuitive Machines adjusted the descent burn parameters based on data from the lunar orbit insertion burn. IM indicated the risks undertaken during the lunar landing phase of the mission would be a "challenge". [55] A later report indicated that, as the lander was being prepared for its descent to the surface, mission controllers determined a safety switch on the primary laser rangefinder system had not been activated during pre-launch preparations. [38] Teams on the ground worked around the issue by reprogramming Odysseus to use data from an experimental NASA payload, the Navigation Doppler Lidar for Precise Velocity and Range Sensing. [59]
A favored landing site in 2020 was between the Sea of Serenity (Mare Serenitatis) and the Sea of Crises (Mare Crisium). [60] [61] Lunar maria are large plains formed when lava flowed into ancient impact basins. Later, a lunar highlands location near the south pole of the Moon was chosen for the landing, since that region is believed to have a source of water for a future lunar base. [62]
The Malapert-A crater area 300 km (190 mi) from the lunar south pole was chosen because it appeared to be a relatively flat and safe place near the pole to land, amongst other considerations. [62] [63]
After making a last-minute software patch to the lander's altitude monitoring systems, Odysseus began its landing sequence at 23:11 UTC (6:11 p.m. EST) on February 22 and landed near Malapert A—an area determined to contain water ice—at 23:23 UTC (6:23 p.m. EST). [64] Controllers confirmed that faint communications were received from the lander. [65] The lander was initially thought to be in a fully vertical orientation, [59] [66] based on stale telemetry. It was later determined to have landed at a 30 degree angle, with its solar panels and scientific instrumentation functionally oriented, but with its radio transmission rates somewhat reduced due to the unexpected angle of the lander's antennas.
The lander appeared to most probably have lost one or more of its 6 landing struts and to be resting on an externally mounted helium tank. [67] [68] (The only non-functional payload is a passive Moon Phases art sculpture, on the side facing towards the ground.) [41] Odysseus became the first American spacecraft moon landing since the Apollo 17 mission in 1972 and the first commercial lunar lander. [69] The Lunar Crater Observation and Sensing Satellite made an intentional hard landing in 2009 following deorbit.
Reporting by Kenneth Chang in The New York Times [70] includes a detailed description of the landing anomaly:
Tim Crain, the company’s chief technology officer, said the spacecraft had been designed to stay upright when landing even on a slope of 10 degrees or more. The navigation software was programmed to look for a spot where the slope was five degrees or less. Because the laser instruments on Odysseus for measuring altitude were not working during descent, the spacecraft landed faster than planned on a 12-degree slope. That exceeded its design limits. Odysseus skidded along the surface, broke one of its six legs and tipped to its side.
On February 23, Intuitive Machines reported that the IM-1 Odysseus lander was still "alive and well", and that IM was continuing to receive data on the vehicle's status [71] and whether the scientific payloads could still be deployed. [72] [68] Intuitive Machines executives said they were working to reconfigure antennas to increase downlink rates but did not estimate what sort of data rates they expected. [73]
On February 26, Intuitive Machines released the first images from the surface taken by the lunar probe. [74] Based on Earth and moon positioning, the IM team reported that flight controllers would continue to communicate with Odysseus until Tuesday (February 27) morning. [75] As of February 28, Odysseus was still receiving power, and all six NASA payloads were providing good data. [42] In a press conference the same day, Intuitive Machines said the lander was in its final hours of operation as the sun moved out of view of the one illuminated solar panel. [7] On February 29, Odysseus lost power and shut down with the start of the lunar night. [3] However, the company did not rule out bringing Odysseus back to life after the two-week lunar night. Executives said they would try contacting the lander in two to three weeks. [7]
About one month after Odysseus landed on the Moon, Intuitive Machines reported that they could not re-establish contact with the lander after the lunar night, bringing an end to the IM-1 mission. [4]
Mission type | Technology demonstration |
---|---|
Operator | Embry-Riddle Aeronautical University Intuitive Machines |
COSPAR ID | 2024-030A |
SATCAT no. | 58963 |
Website | https://erau.edu/eaglecam |
Mission duration | Launch to Landing: 13 days On surface: 30 minutes (lifespan) |
Spacecraft properties | |
Spacecraft | EagleCam |
Spacecraft type | CubeSat |
Bus | 1.5U CubeSat |
Manufacturer | ERAU Space Technologies Laboratory |
Dimensions | 100 mm x 100 mm x 150 mm [76] |
Start of mission | |
Launch date | February 15, 2024, 06:05:37 UTC |
Rocket | Falcon 9 Block 5 F9-299 |
Launch site | LC-39A |
Contractor | SpaceX |
Deployed from | Nova-C Odysseus lander |
End of mission | |
Disposal | Decommissioned |
Declared | March 31, 2024 |
Lunar lander | |
Landing date | February 28, 2024 |
Landing site | 4 m (13 ft) away from Odysseus lander, near Malapert A crater |
The EagleCam was a deployable CubeSat camera system designed especially to photograph the lunar landing of the Nova-C Odysseus lander on the Moon. Photographs taken during the lunar landing of the Odysseus lander may also have enabled a better understanding of the dynamics of lunar landings on the lunar regolith and rock surfaces in the vicinity of the Moon's south pole. Such a better understanding of the local lunar surface features would have assisted with preparations for upcoming scheduled additional landings at the lunar south pole. [40] [77] Designed and manufactured by staff and students working in the Space Technologies Laboratory at Embry–Riddle Aeronautical University, Daytona Beach, [40] [77] it was intended to deploy from Odysseus and take the first photographs of a spacecraft landing on the moon from a third-person perspective. It also planned to test an electrodynamic dust shield system in space for the first time and utilize a Wi-Fi connection to transmit data for the first time on the lunar surface.
EagleCam's primary payload was its camera system, consisting of three fisheye-lens [78] : 2 cameras which would take a total of nine images per second over six seconds as it was ejected from Odysseus shortly before landing. A fourth [79] camera was included to test another one of EagleCam's payloads, an electrodynamic dust shield (EDS), created by the Swamp Works facility at Kennedy Space Center. [80] The CubeSat was powered from a solar-powered battery with a lifetime of 30 minutes. [81]
Had EagleCam been successful, photographs and data taken during the lunar landing of the Odysseus lander may have enabled a better understanding of the dynamics of lunar landings on the lunar regolith and rock surfaces in the vicinity of the Moon's south pole. EagleCam would've assisted in the objectives of NASA's Commercial Lunar Payload Services (CLPS) program, such as gaining a better understanding of the local lunar surface features to assist with preparations for future manned and unmanned missions to the Moon's south pole, through NASA's Artemis program. [82] [83] However, while photos of Odysseus were never taken by EagleCam, it still recorded and transmitted other types of data to Intuitive Machines and the Space Technologies Lab via the IM-1 lander. [84] Through EagleCam, Embry-Riddle Aeronautical University became the world's first university to have a payload on the moon's surface solely developed by faculty and students. [80] [82] [lower-alpha 1]
A prototype of the EagleCam CubeSat flew onboard the Blue Origin NS-24 return-to-flight mission on December 19, 2023. [89]
Just before landing, at approximately 30 m (98 ft) above the lunar surface, Odysseus was to eject this CubeSat. Once ejected, EagleCam was supposed to semi-hard land on the lunar surface somewhere near the lander at 10 m/s (33 ft/s). As it descended to the surface EagleCam was planned to capture the first third-person images of a lunar landing. [90] However, due to complications arising from a software patch which reconfigured the lander's sensors used during the final descent phase to the moon's surface, EagleCam was powered off and remained attached to Odysseus through landing. [91] [79] It was later ejected on February 28 but was a partial failure as it returned all types of data, except post IM-1 landing images that were the main aim of its mission. [92] [93] [94] [95] [96] [84] “We reset the visual processing unit and powered up the EagleCam, and were able to eject it, and (we) ejected it about 4 meters away from the vehicle safely. However, either in camera or in the Wi-Fi signal back to the lander, something might not be working correctly. So, the Embry‑Riddle team is working on that and wrestling with that to see if there’s anything they can do,” Steve Altemus, CEO of Intuitive Machines commented on EagleCam in a NASA-IM mission update. [97] The EagleCam utilized a Wi-Fi connection with the Odysseus lander to relay its images back to Earth. [82]
In March 2024, the EagleCam team was recognized by U.S. Senator Rick Scott in the Congressional Record of the United States Senate for their achievements. [98]
A lander is a spacecraft that descends towards, then comes to rest on the surface of an astronomical body other than Earth. In contrast to an impact probe, which makes a hard landing that damages or destroys the probe upon reaching the surface, a lander makes a soft landing after which the probe remains functional.
A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959.
A lunar lander or Moon lander is a spacecraft designed to land on the surface of the Moon. As of 2024, the Apollo Lunar Module is the only lunar lander to have ever been used in human spaceflight, completing six lunar landings from 1969 to 1972 during the United States' Apollo Program. Several robotic landers have reached the surface, and some have returned samples to Earth.
Astrobotic Technology, Inc., commonly referred to as Astrobotic, is an American private company that is developing space robotics technology for lunar and planetary missions. It was founded in 2007 by Carnegie Mellon professor Red Whittaker and his associates with the goal of winning the Google Lunar X Prize. The company is based in Pittsburgh, Pennsylvania. Their first launch occurred on January 8, 2024, as part of NASA's Commercial Lunar Payload Services (CLPS) program. The launch carried the company's Peregrine lunar lander on board the first flight of the Vulcan Centaur rocket from Florida's Space Force Station LC-41. The mission was unable to reach the Moon for a soft or hard landing. On June 11, 2020, Astrobotic received a second contract for the CLPS program. NASA would pay Astrobotic US$199.5 million to take the VIPER rover to the Moon, targeting a landing in November 2024. In July 2024, NASA announced that VIPER had been cancelled.
The lunar south pole is the southernmost point on the Moon. It is of interest to scientists because of the occurrence of water ice in permanently shadowed areas around it. The lunar south pole region features craters that are unique in that the near-constant sunlight does not reach their interior. Such craters are cold traps that contain fossil records of hydrogen, water ice, and other volatiles dating from the early Solar System. In contrast, the lunar north pole region exhibits a much lower quantity of similarly sheltered craters.
Moon Express is an American privately held company formed in 2010 by a group of Silicon Valley and space entrepreneurs. It had the goal of winning the $30 million Google Lunar X Prize, and of ultimately mining the Moon for natural resources of economic value. The company was not able to make a launch attempt to reach the Moon by March 31, 2018, the deadline for the prize.
The year 2024 is expected to exceed 2023's 223 orbital launches. So far, the year saw the successful first launch of Vulcan Centaur, Gravity-1, Ariane 6, and notably more developmental launches of SpaceX's Starship – with IFT-5, and IFT-6 planned for this year. Additionally, the final launch of a Delta family rocket occurred in April with a Delta IV Heavy. In May, China launched the Chang'e 6, the first sample return from the far side of the Moon. The Polaris Dawn mission conducted the first ever commercial spacewalk in September.
The International Lunar Observatory (ILO) is a private scientific and commercial lunar mission by the International Lunar Observatory Association of Kamuela, Hawaii to place a permanent observatory near the South Pole of the Moon to conduct astrophysical studies using an optical telescope and possibly an antenna dish. The mission aims to prove a conceptual design for a lunar observatory that would be reliable, low cost, and fast to implement. A precursor mission, ILO-X consisting of two small imagers, launched on 15 February 2024 aboard the Intuitive Machines IM-1 mission to the Moon south pole region. It is hoped to be a technology precursor to a future observatories on the Moon, and other commercial initiatives.
MoonLIGHT is a laser retroreflector developed as a collaboration primarily between the University of Maryland in the United States, and the Italian National Institute for Nuclear Physics - National Laboratories of Frascati (INFN-LNF) to complement and expand on the Lunar Laser Ranging experiment started with the Apollo Program in 1969. MoonLIGHT was planned to be launched in July 2020 as a secondary payload on the MX-1E lunar lander built by the private company Moon Express. However, as of February 2020, the launch of the MX-1E has been canceled. In 2018 INFN proposed to the European Space Agency (ESA) the MoonLIGHT Pointing Actuators (MPAc) project and was contracted by ESA to deliver it. MPAc is an INFN development for ESA, with auxiliary support by the Italian Space Agency (ASI) for prototyping work. In 2021, ESA agreed with NASA to launch MPAc with a Commercial Lunar Payload Services (CLPS) mission. Nova-C, the lander on which MPAc will be integrated, is designed by Intuitive Machines and the landing site is Reiner Gamma. The expected launch date of the Nova-C mission carrying the instrument, IM-3, is in 2025.
Commercial Lunar Payload Services (CLPS) is a NASA program to hire companies to send small robotic landers and rovers to the Moon. Most landing sites are near the lunar south pole where they will scout for lunar resources, test in situ resource utilization (ISRU) concepts, and perform lunar science to support the Artemis lunar program. CLPS is intended to buy end-to-end payload services between Earth and the lunar surface using fixed-price contracts. The program achieved the first landing on the moon by a commercial company in history with the IM-1 mission in 2024. The program was extended to add support for large payloads starting after 2025.
The Intuitive Machines Nova-C, or simply Nova-C, is a class of lunar landers designed by Intuitive Machines (IM) to deliver small payloads to the surface of the Moon. Intuitive Machines was one of three service providers awarded task orders in 2019 for delivery of NASA science payloads to the Moon. The IM-1 lunar lander, named Odysseus, was launched by a SpaceX Falcon 9 rocket on 15 February 2024, reached lunar orbit on 21 February, and landed on the lunar surface on 22 February. This marked the inaugural Nova-C landing on the Moon and the first American spacecraft to perform a soft landing on the Moon in over 50 years. It is the first spacecraft to use methalox propulsion to navigate between the Earth and the Moon.
Intuitive Machines, Inc. is an American space exploration company headquartered in Houston, Texas. It was founded in 2013 by Stephen Altemus, Kam Ghaffarian, and Tim Crain, to provide lunar surface access, lunar orbit delivery, and communication from lunar distance. Intuitive Machines holds three NASA contracts under the space agency's Commercial Lunar Payload Services (CLPS) programme, to deliver payloads to the lunar surface. Among these, the company holds a contract to develop a Lunar Terrain Vehicle (LTV).
The Artemis program is a Moon exploration program led by the United States' National Aeronautics and Space Administration (NASA), formally established in 2017 via Space Policy Directive 1. It is intended to reestablish a human presence on the Moon for the first time since the Apollo 17 mission in 1972. The program's stated long-term goal is to establish a permanent base on the Moon to facilitate human missions to Mars.
Peregrine Lunar Lander flight 01, commonly referred to as Peregrine Mission One, was an unsuccessful American lunar lander mission. The lander, dubbed Peregrine, was built by Astrobotic Technology and carried payloads for the NASA Commercial Lunar Payload Services (CLPS) program. Peregrine Mission One launched on 8 January 2024, at 2:18 am EST, on the maiden flight of the Vulcan Centaur (Vulcan) rocket. The goal was to land the first U.S.-built lunar lander on the Moon since the crewed Apollo Lunar Module on Apollo 17 in 1972.
Kamal "Kam" Ghaffarian is an Iranian-born American businessman who focuses on the space industry and new energies and is known as the co-founder of IBX, Axiom Space, Intuitive Machines, X-energy and Quantum Space.
IM-2 is an upcoming lunar mission that will be carried out in January 2025 by Intuitive Machines for NASA's CLPS program, using a Nova-C lunar lander. The company named this lander Athena. The mission aims to uncover the presence and amount of lunar water ice using PRIME-1, which consists of a drill and mass spectrometer. The lander will carry a Micro Nova Hopper, a drone that will utilize its neutron spectrometer in the PSR of the nearby Marston crater. If successful, this would provide the first measurement of hydrogen on the surface in the PSR, a key indicator of water.
Small Innovative Missions for Planetary Exploration (SIMPLEx) is a planetary exploration program operated by NASA. The program funds small, low-cost spacecraft for stand-alone planetary exploration missions. These spacecraft are intended to launch as secondary payloads on other missions and are riskier than Discovery or New Frontiers missions.