Saturday , April 17 2021

Tiny satellites to report back to Earth at InSight landing on Mars



The next spacecraft to land on Mars is bringing its own communications team. InSight, a lander scheduled to land on the Red Planet on November 26, is accompanied by a pair of spacecraft that will send landing details to Earth in near-real time.

The twin ships on this mission are CubeSats – small and inexpensive satellites that are easy to build and launch. Called Mars Cube One, or MarCO, they will pass through Mars as InSight lands, making it the smallest spacecraft to be entrusted with a task as crucial as transmitting landing information to a mission. Now, as they approach Mars, they are already the first CubeSats to come this far from Earth. If all goes well with InSight's landing, Mars's future missions can also be equipped with its own single-use communications team.

"A future where landers and rovers brought their own communication systems to land, that would be fantastic," says engineer Joel Krajewski of NASA's Jet Propulsion Laboratory in Pasadena, Calif., And Marco's program manager.

InSight – abbreviation for Inner Exploration using Seismic Investigations, Geodesy and Heat Transport – will bring the first seismograph to Mars (SN: 5/26/18, p. 13). After touching a wide flat plain called the Elysium Planitia, near the equator of Mars, the probe will be perfectly stopped to hear the seismic waves and measure how the heat flows through the interior of the Red Planet. The results will help scientists understand how Mars, and perhaps other rocky planets such as Earth, formed about 4.5 billion years ago.

It will be only six and a half minutes between the time InSight enters the Martian atmosphere at a speed of almost 1,000 meters per second until the moment its legs touch the ground. The spacecraft will use a parachute and rockets aimed at the ground to reduce speed to about 2.4 meters per second. The light speed signals from the CubeSats or Insight itself will take about eight minutes to travel between Earth and Mars, so when NASA engineers hear that InSight has entered the Mars atmosphere, the spacecraft will be on the ground.

"What is terrifying," says engineer Farah Alibay, also of the Jet Propulsion Laboratory. "Whether it landed softly or very hard, we will not know. But we'll know when you get the first bit of data, InSight has already landed. "

We're listening.

The MarCO CubeSats will watch the descent of InSight to the Martian surface (red line) and send landing details back to Earth before continuing to pass through the planet.

For most of Mars' previous landings, one of the major orbiting the Red Planet has to pause its data to watch the event and send details to Earth. The orbiter that will be in the best position to watch InSight will be NASA's Mars Reconnaissance Orbiter. While the spacecraft will observe the landing, it will not be able to transmit details to Earth for at least three hours, as its orbit takes the spacecraft behind Mars from the Earth's viewpoint, blocking communications.

"Three to four hours are not long for most people, but it's too long for us," says Alibay. "Landing is the scariest part of your mission." Waiting to hear about the spacecraft landing is like waiting for news of a loved one's health, she says.

To avoid this wait, the team sent the twin CubeSats. The spacecraft was launched with InSight, but has been sailing in space on its own since May. Marco's craft can change its trajectories by expelling compressed cold gas, similar to the way a fire extinguisher works – which earned them the nicknames Wall-E and Eve among the team, after the Disney robot characters flying in space. "We have shown that a CubeSat can leave the Earth's orbit, survive the hostile environment of space and go to Mars," says Alibay.

About five minutes before InSight reaches the top of the Martian atmosphere, the two MarCO spacecrafts will position themselves to track the probe to the ground and send the details back to Earth immediately. Each operates independently, supporting each other.

If things go well, Marco could set a precedent for future missions on Mars. The current Mars orbiter will support two Mars missions to be launched in 2020 – NASA's Mars 2020 rover and the ExoMars rover, operated by the European Space Agency and the Russian space agency. But after that, the future is bleak.

"At the moment, there is no active plan for an orbiter beyond that period," says Krajewski. In addition, existing orbiting need to burn fuel to get into the correct position to observe other spacecraft, which shortens the life of the orbiter. Sending forth future spacecraft with its own CubeSat communications team can help scientists monitor landings without compromising the scientific missions of the great orbiter.

After the lands of InSight, the work of MarCO will be completed. The small spacecraft does not have enough fuel or the right equipment to go into long-term orbit around Mars. Instead, Marco will "wave goodbye and continue," says Krajewski.

You can watch InSight by landing online on NASA TV.


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