InSight Mission

Mar’s Solar Conjuction — What Is It & What It Means

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Andrew Good
Jet Propulsion Laboratory, Pasadena, Calif.
andrew.c.good@jpl.nasa.gov

Alana Johnson
NASA Headquarters, Washington
alana.r.johnson@nasa.gov

 

 

This animation illustrates Mars solar conjunction, a period when Mars is on the opposite side of the Sun from Earth. During this time, the Sun can interrupt radio transmissions to spacecraft on and around the Red Planet. Credit: NASA/JPL-Caltech

 

The daily chatter between antennas here on Earth and those on NASA spacecraft at Mars is about to get much quieter for a few weeks. 

That’s because Mars and Earth will be on opposite sides of the Sun, a period known as Mars solar conjunction. The Sun expels hot, ionized gas from its corona, which extends far into space. During solar conjunction, this gas can interfere with radio signals when engineers try to communicate with spacecraft at Mars, corrupting commands and resulting in unexpected behavior from our deep space explorers. 

 

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When NASA launches its next mission on the journey to Mars – a stationary lander in 2016 – the flight will include two CubeSats. This will be the first time CubeSats have flown in deep space.  If this flyby demonstration is successful, the technology will provide NASA the ability to quickly transmit status information about the main spacecraft after it lands on Mars.

The twin communications-relay CubeSats, being built by NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California, constitute a technology demonstration called Mars Cube One (MarCO).  CubeSats are a class of spacecraft based on a standardized small size and modular use of off-the-shelf technologies. Many have been made by university students, and dozens have been launched into Earth orbit using extra payload mass available on launches of larger spacecraft.

 

The full-scale mock-up of NASA’s MarCO CubeSat held by Farah Alibay, a systems engineer for the technology demonstration, is dwarfed by the one-half-scale model of NASA’s Mars Reconnaissance Orbiter behind her.

Credits: NASA/JPL-Caltech

The basic CubeSat unit is a box roughly 4 inches (10 centimeters) square. Larger CubeSats are multiples of that unit. MarCO’s design is a six-unit CubeSat – about the size of a briefcase — with a stowed size of about 14.4 inches (36.6 centimeters) by 9.5 inches (24.3 centimeters) by 4.6 inches (11.8 centimeters).

MarCO will launch in March 2016 from Vandenberg Air Force Base, California on the same United Launch Alliance Atlas V rocket as NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander. Insight is NASA’s first mission to understand the interior structure of the Red Planet. MarCO will fly by Mars while InSight is landing, in September 2016.

“MarCO is an experimental capability that has been added to the InSight mission, but is not needed for mission success,” said Jim Green, director of NASA’s planetary science division at the agency’s headquarters in Washington. “MarCO will fly independently to Mars.”

During InSight’s entry, descent and landing (EDL) operations on Sept. 28, 2016, the lander will transmit information in the UHF radio band to NASA’s Mars Reconnaissance Orbiter (MRO) flying overhead. MRO will forward EDL information to Earth using a radio frequency in the X band, but cannot simultaneously receive information over one band while transmitting on another. Confirmation of a successful landing could be received by the orbiter more than an hour before it’s relayed to Earth.

MarCO’s radio is about softball-size and provides both UHF (receive only) and X-band (receive and transmit) functions capable of immediately relaying information received over UHF.

The two CubeSats will separate from the Atlas V booster after launch and travel along their own trajectories to the Red Planet. After release from the launch vehicle, MarCO’s first challenges are to deploy two radio antennas and two solar panels. The high-gain, X-band antenna is a flat panel engineered to direct radio waves the way a parabolic dish antenna does. MarCO will be navigated to Mars independently of the InSight spacecraft, with its own course adjustments on the way.

Ultimately, if the MarCO demonstration mission succeeds, it could allow for a “bring-your-own” communications relay option for use by future Mars missions in the critical few minutes between Martian atmospheric entry and touchdown.

By verifying CubeSats are a viable technology for interplanetary missions, and feasible on a short development timeline, this technology demonstration could lead to many other applications to explore and study our solar system.

JPL manages MarCO, InSight and MRO for NASA’s Science Mission Directorate in Washington. Technology suppliers for MarCO include: Blue Canyon Technologies of Boulder, Colorado, for the attitude-control system; VACCO Industries of South El Monte, California, for the propulsion system; AstroDev of Ann Arbor, Michigan, for electronics; MMA Design LLC, also of Boulder, for solar arrays; and Tyvak Nano-Satellite Systems Inc., a Terran Orbital Company in San Luis Obispo, California, for the CubeSat dispenser system. 

For information about MarCO, visit: http://www.jpl.nasa.gov/cubesat/missions/marco

For information about InSight, visit: http://www.nasa.gov/insight

Learn more about NASA’s journey to Mars at: http://www.nasa.gov/content/journey-to-mars-overview