Starlink has been a game-changer. SpaceX initially showcased the satellite constellation’s potential with live uncut footage of Falcon 9 landings. However, Thursday’s live streaming of Starship's complete re-entry into Earth's atmosphere, from the moment it entered the plasma until it landed in the Indian Ocean, has exceeded all expectations.
Goodbye to the Communications Blackout
Atmospheric re-entry is one of the most critical moments of all space missions. Given that spacecraft travel at hypersonic speeds of up to 17,400 miles per hour, almost every spacecraft has experienced communications outages as they've descended into Earth’s atmosphere.
The Gemini missions in 1965 were the first to test a more durable heat shield that could withstand longer flights and hypersonic speed re-entry. During re-entry, the spacecraft experienced a four-minute blackout in radio communications when it hit a thicker layer of the atmosphere nine minutes after starting its descent. Similarly, during the Apollo missions, the communication blackout lasted about three minutes, with the duration being affected by the entry angle.
This phenomenon, known as a “communications blackout” or “radio blackout,” is caused by the heat generated from the compression of the atmosphere. The heat ionizes the air around the spacecraft, causing interference with radio signals.
In the case of Starship, Starlink antennas are protected by the same ceramic material as the spacecraft’s heat shield. The frequency of these antennas not only penetrates the plasma barrier but also enables the transmission of high-definition video, connecting with Starlink's network of 6,000 satellites.
What About the “Seven Minutes of Terror”?
Mars has a much thinner atmosphere than Earth, which makes landing on Mars much more difficult. As a result, NASA uses the expression “seven minutes of terror” to describe the entry, descent, and landing (EDL) maneuver of a spacecraft on the Martian surface. This is because telemetry from the spacecraft is delayed by several minutes.
In order to enhance communication during future Mars missions, SpaceX and NASA are exploring the possibility of setting up a satellite network similar to Starlink around the red planet. Although the signal will still take several minutes to reach Earth, it’s hoped that the nerve-wracking “seven minutes of terror” will eventually be replaced by the transmission of spectacular videos using the high bandwidth provided by the satellites’ laser links. These links, by the way, could be established across stable orbits in the solar system.
Laser communications aren’t common in space. However, NASA’s Psyche probe made history as the first spacecraft equipped with a laser transceiver. In December 2023, it beamed a 4K video of a cat from a distance of nearly 19 million miles and then further broke the distance record by sending its telemetry data at 25 Mbps from a location 140 million miles from Earth.
Image | SpaceX
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