Far above the planet, a spacecraft carrying human hopes must stay within reach of the people who guide it, and that reach depends on the patient geometry of satellites and ground stations spread across distant islands. In late April 2021, reports from New Delhi suggested India's space agency is preparing a dedicated relay satellite, costing about Rs. 800 crore, to close the gaps where Gaganyaan's signals could fall silent. It is a quiet, practical step in a long human project, one that asks the nation to reach upward and send its own messenger between the crew and home before astronauts take t
ISRO Plans Own Data Relay Satellite to Maintain Contact During Gaganyaan Missions
A satellite whose only job is to keep Gaganyaan in touch with the ground
Mark
So what is ISRO actually planning here?
Mimi
A satellite whose job is to relay data. It would keep Gaganyaan in contact after launch, filling gaps that ground stations leave.
Mark
Why are there gaps at all?
Mimi
A satellite can only talk to a ground station it can see. ISRO uses stations in Mauritius, Brunei and Biak, Indonesia, and the sources say blind spots remain where signals might not arrive.
Luke
Worth flagging that all of this is attributed to unnamed sources. The Rs. 800-crore figure and the approval haven't been confirmed on the record in this report.
Mark
Fair. Is there a precedent for this?
Mimi
NASA's Tracking and Data Relay Satellite system. It gives round-the-clock global coverage without extra ground stations.
Mark
And India is also still adding ground stations?
Mimi
Yes. Sivan said last month that ISRO was in talks with Australia about a station at the Coco islands.
Luke
Talks, though, not a deal. And we don't know when the relay satellite launches, only that it comes before the crewed leg.
Mark
What else is in motion?
Mimi
A CNES agreement for training flight physicians and supplying tested equipment, and four prospective astronauts back from nearly a year in Russia.
Luke
The December date applies to the unmanned flight. Nothing here says the crewed date.
Le Pouls
- Signals from a crewed mission can vanish in the blind spots of today's ground station network, and ISRO has no margin for lost contact.
- Mauritius, Brunei and Biak cover the globe unevenly, so engineers are looking to a satellite to bridge what ground stations cannot reach.
- A Rs. 800-crore relay satellite is reportedly approved and already under work, racing to be in orbit before the crewed flight.
- The unmanned Gaganyaan test in December sets the clock, and no launch date for the relay satellite has been confirmed yet.
- Details still rest on unnamed sources, so the program's next move awaits an official announcement.
Far above the planet, a spacecraft carrying human hopes must stay within reach of the people who guide it, and that reach depends on the patient geometry of satellites and ground stations spread across distant islands. In late April 2021, reports from New Delhi suggested India's space agency is preparing a dedicated relay satellite, costing about Rs. 800 crore, to close the gaps where Gaganyaan's signals could fall silent. It is a quiet, practical step in a long human project, one that asks the nation to reach upward and send its own messenger between the crew and home before astronauts take their first flight.
India's space agency is reportedly preparing to build and launch its own data relay satellite, a spacecraft whose sole job would be to keep Gaganyaan, the human spaceflight program, in constant contact with the ground. The report, carried from New Delhi on April 25 and based on unnamed sources, puts the project at Rs. 800 crore and says it has already been approved and work has begun.
The reason is geometry. A satellite can only send its data to a ground station when it has a clear line of sight, and ISRO's current stations in Mauritius, Brunei and Biak leave gaps where signals may be lost. A relay satellite sits between them and passes the information along, closing those gaps without requiring ever more stations on the ground. NASA already works this way with its own relay network, giving it near-constant coverage.
The program has been busy this month. ISRO signed an agreement with France's space agency CNES that lets Indian flight doctors train in France and gives Indian crews access to French equipment that has already flown on the International Space Station. Four prospective astronauts also returned to India after nearly a year in Russia.
For now the calendar is set by the unmanned flight in December, and the relay satellite is expected to fly before any astronaut does. No launch date has been announced, and the details await official confirmation.
India's space agency is preparing to build and launch its own data relay satellite, a spacecraft whose only job would be to keep Gaganyaan, the country's human spaceflight program, in touch with the ground. The news, reported on April 25 from New Delhi and attributed to unnamed sources, comes with a price tag: the project is said to cost Rs. 800 crore, and it has reportedly been approved, with work already underway.
The sources said the satellite would fly before the final leg of Gaganyaan, the stage that would carry astronauts into low Earth orbit. The first stage, an unmanned mission, is scheduled to launch in December. "We're planning to launch our own satellite, which will act as a data relay satellite before going for the first human space flight," the sources said.
The problem it addresses is geometry. A satellite in orbit cannot pass its information to a ground station unless it has a clear line of sight to that station. A data relay satellite sits in between and carries the information along. According to the report, ISRO's current network has blind spots where signals may not be received, and the new satellite is meant to close those gaps.
That network is spread around the globe. ISRO uses ground stations in Mauritius, Brunei and Biak, in Indonesia. Last month, ISRO Chairperson K Sivan said the agency was also talking with its Australian counterpart about placing a ground station at the Coco islands for Gaganyaan. A relay satellite would reduce the need to keep adding stations on the ground.
NASA offers the obvious comparison. With its long-running human spaceflight program, it operates its own Tracking and Data Relay Satellite system, which gives it round-the-clock global coverage of its satellites without building extra ground stations on Earth.
The relay satellite is one piece of a busier month for the program. Earlier in April, ISRO signed a cooperation agreement with the French space agency CNES for Gaganyaan. It will allow Indian flight physicians to train at CNES facilities. Under the same agreement, French equipment developed by CNES, tested and still operating aboard the International Space Station, will be made available to Indian crews. CNES will also supply French-made fireproof carry bags designed to protect equipment from shocks and radiation.
The human side of the program also moved forward last month, when four prospective astronauts returned to India after spending nearly a year in Russia.
What to watch now is timing. The December unmanned flight is the next fixed date, and the relay satellite is expected to be in orbit before astronauts fly. No launch date for the satellite has been given in the reporting, and the details so far rest on unnamed sources rather than an official announcement.
Citations marquantes
We're planning to launch our own satellite, which will act as a data relay satellite before going for the first human space flight.— Unnamed sources, as reported by Oneindia
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